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FACILITIES INSTRUCTIONS, STANDARDS,
AND TECHNIQUES
Volume 3-10
WATT-HOUR METER
MAINTENANCE AND TESTING
Internet Version of This Manual Created
December 2000
FACILITIES ENGINEERING BRANCH
DENVER OFFICE
DENVER, COLORADO
The Appearance of The Internet Version of This Manual
May Differ From the Original, but the Contents Do Not
UNITED STATES DEPARTMENT OF THE INTERIOR
BUREAU OF RECLAMATION
WATT-HOUR METER MAINTENANCE AND TESTING
Volume 3-10
CONTENTS
Section Page
I. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1. General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1 1.2. Selection of Meters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
II. Test Schedules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2.1. Frequency of Tests and Servicing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
III. Watt-Hour Meter Operating Principles and Construction . . . . . . . . . . . . . . . . 4
3.1. General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.2. Basic Single-Phase Meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.3. Disk Driving Torque . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.4. Friction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.5. Braking Magnets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.6. Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.7. Multielement Meters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.8. Detents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.9. Meter Constants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.10. Primary Versus Secondary Constants . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.11. Formulas for Constants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.12. Base-Load Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.13. Meter Connection Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
IV. Metering Power in 3-Phase Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.1. Methods for Metering 3-Phase Power . . . . . . . . . . . . . . . . . . . . . . . . . . 9
V. Metering Vars and Volt-Amperes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5.1. General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5.2. Var Metering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5.3. Volt-Ampere Metering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
i (FIST 3-10 1/92)
CONTENTS - Continued
Section Page
VI. Errors in Watt-Hour Metering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
6.1. Meter Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
6.2. Instrument Transformer Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
6.3. Sources of Meter Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
VII. Meter Test Equipment and Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
7.1. Test Leads and Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
7.2. Portable Standard Waft-Hour Meter . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
7.3. Loading Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
7.4. Meter Test Blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
7.5. Errors Due to Improper Test Connections . . . . . . . . . . . . . . . . . . . . . 27
7.6. Test Supply Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
7.7. Test Connection Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
7.8. Tests at 50-Percent Power Factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
VIII. Pretest Checking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
8.1. Verification of Meter Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
8.2. Checking Instrument Transformer Burden . . . . . . . . . . . . . . . . . . . . . 32
8.3. Creep . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
IX. Meter Servicing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
9.1. "As Found" Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
9.2. Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
9.3. Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
9.4. Registers and Gears . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
X. Test Procedures and Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
10.1. Test Runs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
10.2. Test Loading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
10.3. Adjustments, General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
10.4. "As Found" Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
10.5. Calibration Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
10.6. Concluding the Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
10.7. Meter Test Records . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
(FIST 3-10 1/92) ii
CONTENTS - Continued
Section Page
XI. Demand and Totalizing Meters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
11.1 Indicating Demand Meter 42
11.2. Recording Demand Meters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Appendix A-Suggested Guidelines for Maintaining Revenue
Metering Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
A-1. Types of Meter Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
a. Routing Field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
b. Precise Field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
c. Laboratory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
A-2. Frequency of Meter Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
A-3. Rotating Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
a. Minimum Required . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
b. Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
A. PRECISE METER TESTS
A-4. Test Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
a. Warmup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
b. Final Clearance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
c. "As Found" Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
d. "As Left" Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
e. Permissible Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
f. Comparison of Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
A-5. Conclusion of Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
B. SUPPLEMENTAL INFORMATION
A-6. Metering Correction Factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
A-7. Metering Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
A-8. Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
iii (FIST 3-10 1/92)
CONTENTS - Continued
Section Page
C. ROUTINE METER TESTS
A-9. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
A-10. Preliminary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
A-11. Test Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
a. Instrument Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
b. Warmup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
c. Equipment removal from service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
d. "As Found" Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
e. Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
f. Indicating Demand Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
g. "As Left" Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
h. Permissible Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
i. Equipment Return to Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
A-12. Conclusion of Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
D. PERIODIC OR MIDMONTH INSPECTIONS
A-13. Requirement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
a. Inspection Schedules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
b. Inspection of Metering Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
c. Magnetic Tape Recorders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
d. Watt-hour-demand Meters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
A-14. Reports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
E. MANUFACTURERS' CATALOGS AND INSTRUCTION BOOKS
A-15. General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
A-16. General Electric Company . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
a. Instruction Books . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
b. Spare Parts Catalog . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
c. Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
(FIST 3-10 1/92) iv
CONTENTS - Continued
Section Page
A-17. Westinghouse Electric Corporation . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
a. Instruction, Operation and Maintenance Catalogs . . . . . . . . . . . . . . . 64
b. Descriptive Catalogs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
c. Renewal Parts Catalogs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
d. Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
A-18. Beckman Instruments, Inc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
a. Instruction Book . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
b. Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
A-19. Duncan Electric Company . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
a. General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
b. Instruction Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
c. Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
A-20. Edison Electric Institute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
a. Handbook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
b. Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
LIST OF FIGURES
Figure Page
1 Watthour metering equipment selection chart, sheet 1 of 2 . . . . . . . . . 2
2 Watthour metering equipment selection chart, sheet 2 of 2 . . . . . . . . . 3
3 Vector diagram o1 watt-hour meter element . . . . . . . . . . . . . . . . . . . . . . 5
4 Fundamentals of a single-phase induction watt-hour meter . . . . . . . . . 5
5 Magnetic shunt method of adjusting speed o1 disk . . . . . . . . . . . . . . . 6
6 Single-phase, 2-wire meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
7 Single-phase, 2-wire meter using instrument transformers . . . . . . . . 10
8 Single-phase, 3-wire meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
9 Single-phase, 3-wire circuit using 2-wire meter and current
transformers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
10 Three-phase, 3-wire, 2-element meter, self-contained . . . . . . . . . . . . . 10
11 Three-phase, 3-wire, 2-element meter, two current
transformers and two potential transformers . . . . . . . . . . . . . . . . . . 11
v (FIST 3-10 1/92)
CONTENTS - Continued
Figure Page
12 Three-phase, 4-wire, 2-1/2-element meter, three current
transformers and two potential transformers . . . . . . . . . . . . . . . . . . . 11
13 Three-phase, 4-wire, 2-element meter with delta-connected
current transformers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
14 Three-phase, 4-wire, 3-element meter . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
15 Power factor chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
16 Single-phase varmeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
17 Varmeter for balanced three-phase circuit . . . . . . . . . . . . . . . . . . . . . . . 19
18 Three-phase varmeter using autotransformers . . . . . . . . . . . . . . . . . . . 20
19 Testing both elements of a meter using resistance load . . . . . . . . . . . 25
20 Testing one element of a meter using phantom load device . . . . . . . . . 26
21 Phase sequence indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
22 Testing single-phase meter using customer's load . . . . . . . . . . . . . . . . 29
23 Sample "watt-hour and demand meter test report" . . . . . . . . . . . . . . . . 41
LIST OF FIGURES IN APPENDIX A
A-1 Calibration of standard wattmeter circuit diagram, direct
comparison method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
A-2 Calibration of rotating standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
A-3 Calibration of rotating standard, electronic method . . . . . . . . . . . . . . 53
(FIST 3-10 1/92) vi
I. SCOPE transformers, by choosing a meter
whose current rating is approximately
1.1. GENERAL. The intent of this vol one-fourth of the probable maximum
ume is to provide general information on sustained load. Modern meters
theory, checks, tests, adjustments, and maintain accuracy within close limits up
records which will serve as a simple and to 667 percent load. Care should be
convenient ready-reference guide for exercised in the selection of current
testing and servicing meters in the field. transformers; over-size can result in
This volume is confined to the type of poor meter accuracy during light load
watt-hour meter most commonly used conditions.
on Reclamation power systems - the 2-,
2-1/2-, and 3-element alternating- It is impractical to show by illustrations
current, induction watt-hour meter rated or to describe the construction, adjust
at 115 volts and 2.5 or 5 amperes used ment locations, constants, etc., of the
with instrument transformers for multitude of meter types that will be
metering relatively large blocks of found in Reclamation installations.
power. However, the material herein will Manufacturer's instructions for the par
provide sufficient information for testing ticular meter should also be referred to,
single-phase and polyphase meters of whenever available, for specific infor
other current and voltage ratings by mation on service procedures,
simple application of the principles constants, etc. The portable standard
discussed. For example, a 15-ampere watt-hour meters which will be used in
meter such as might be used for testing are normally provided with a
residential service would have card giving data on disk constants for
constants three times as large as a various makes and models, which will
similar 5-ampere meter. In the same be helpful in the absence of instruc
way, a meter rated 230 volts would tions. Methods for metering vars and
have constants twice as large as a 115 volt- amperes are discussed in SEC
volt meter. Meters used without TION V. Demand meters are discussed
instrument transformers on single- briefly in SECTION XI.
phase service are commonly rated at 15
or 50 amperes, 230 volts. To sup
plement the general information in this II. TEST SCHEDULES
volume, an appendix devoted specific
ally to revenue metering has been 2.1 FREQUENCY OF TESTS AND
included. SERVICING. To ensure reliability and
accuracy, it is necessary that watt-hour
1.2. SELECTION OF METERS. Meters meters be serviced and tested period
are selected for Reclamation ically. This is of paramount importance for
installations (Figures 1 and 2) so that meters measuring power to customers.
accuracy on reduced loads will be Meters found registering incorrectly are
maintained. This is accomplished by almost invariably slow, which means a
using a 2-1/2-ampere meter with 5 loss of revenue. It is standard utility
ampere current transformers; and in the practice to test customer's meters on
case of meters used without instrument circuits of over 100 - kVA capacity at
1 (FIST 3-10 1/92)
Figure 1
(FIST 3-10 1/92) 2
Figure 2
3 (FIST 3-10 1/92)
least annually. The standard articles in III. WATT-HOUR METER OPERATING
Western (Western Area Power PRINCIPLES AND CONSTRUCTION
Administration) contracts for the sale of
power specify a test annually, or more 3.1. GENERAL. For the sake of simplicity,
often if requested by either party the discussion in this section will be
(Reference, Reclamation Instructions, mainly based on a single-element (single
Part 224, Appendix I, also see Appendix phase) meter. Two- and three-element
A of this volume). meters are simply two or three single
elements having a common shaft and
Most Reclamation watt-hour meters register, which serve to totalize the
should be serviced, tested, and sealed at energy measured by each element.
intervals of not more than 12 months.
Exceptions might be meters measuring 3.2. BASIC SINGLE-PHASE METER. A
very small amounts of power (under 100 single-phase watt-hour meter is es
kVA) or when no sale of power is sentially an induction motor whose speed
involved. The interval in such cases might is directly proportional to the voltage
be extended to 2 years; but for uniformity applied and the amount of current flowing
in scheduling work, it is believed that it will through it. The phase displacement of the
be found most convenient and best current, as well as the magnitude of the
practice to test all watt-hour meters current, is automatically taken into
annually, or more often if circumstances account by the meter. In other words, the
warrant. power factor influences the speed, and
the moving element (disk) rotates with a
When testing billing meters, represen speed proportional to true power. The
tatives of the customer and the power register is simply a means of registering
wheeling agency should be afforded revolutions, and by proper gearing is
opportunity to be present to witness and arranged to read directly in kilowatt-hours.
participate in the test. The meter seal (Note: In some cases, the meter reading
should be broken in the presence of the must be multiplied by a factor called the
witnesses and the meter re-sealed before "register constant" or "meter multiplier" to
their departure. Care and consideration obtain total kilowatt-hours. See "Register
should also be exercised in reading the constant (K), "Paragraph 3.9.4.
register and an agreement reached in
regard to resetting after test, or in 3.3. DISK DRIVING TORQUE. As stated
estimating the energy registration lost above, the meter operates similarly to an
during the meter outage for testing. induction motor. The aluminum disk acts
as a squirrel-cage rotor, torque being
produced as a result of eddy currents
induced in it by the potential (voltage) and
current coils
(FIST 3-10 1/92) 4
on the electromagnet. In order that
registration be correct, the torque (and
speed) must be greatest at a power
factor of 1.0. To have maximum speed at
unity power factor, it is necessary that
the current in the potential coil lag
exactly 90O behind that in the current
coil, or in other words 90O behind the
voltage applied to the potential coil. This
is also necessary if the meter is to
register correctly at power factors less
than unity. (See Figure 3.) To get this
exact 90O displacement, a short- cir
cuited (lag) coil is placed on the voltage
coil pole. (See Figure 4.) The resistor in
the circuit of this coil may constitute the
"lag" or power-factor adjustment of the
meter, but in many meters this
adjustment is obtained by movement of Figure 3. Vector diagram of watt-hour meter
a "lag plate," and the resistor should not element.
be disturbed.
Do not confuse this 90O lag within the
meter at unity power factor, which is
necessary for proper functioning of the
meter, with the current and voltage
supplied to the meter by the instrument
transformers. These are in phase (0O
displacement) at unit (1.0) power factor.
3.4. FRICTION. To compensate for
friction, additional torque must be in
troduced. This usually is accomplished
by placing a movable short-circuited turn
of large cross section in part of the field
of the voltage (potential) coil. This also
serves as a "light-load" adjustment.
3.5. BRAKING MAGNETS. Normally
there is very little friction present in
meters, and if no additional retarding Figure 4. Fundamentals of a single-phase
force other than friction were placed in induction watt-hour meter.
5 (FIST 3-10 1/92)
the meter, the rotating element would is not shown. The moving element
travel at a relatively high speed. The consists of an aluminum disk on a shaft.
necessary retarding action is provided by The bottom bearing may be either of two
a magnetic brake consisting of a types two cupped jewels with a steel ball
permanent magnet operating on the between or a cone- shaped pivot on the
aluminum disk. This retarding action is shaft which rotates in a cupped jewel
adjustable and is known as the "full load" bearing. The top bearing is usually a
meter adjustment. Two methods of varying hardened steel needle-like pin fitting
the braking effect of the magnet are in loosely inside the hollow shaft.
common use. The first is to adjust the
position of the magnet; moving it outward 3.7. MULTIELEMENT METERS.
radially toward the edge of the disk Multielement meters usually consist of
increases the braking effect and additional elements stacked vertically,
decreases speed and registration. In the with two or more disks on the same
second method, the magnet is fixed, and shaft, although meters may be eh-
the braking effect is adjusted by a magnet countered which have more than one
shunt which bypasses part of the magnet electromagnet system acting on the
flux of the permanent magnet, as shown in same disk. Usually there is a set of
Figure 5. permanent magnets per disk, but they
may not all be capable of adjustment.
3.6. BEARINGS. Figure 4 shows the
basic mechanical arrangement and re 3.7.1. Balance adjustment. - In
lationship of the moving element, bearings, multielement meters, an adjustment
permanent magnets, and electro-magnet. must be provided to equalize the
The register which is geared to the shaft torque of the various elements. This
is the "balance" adjustment and may
be a magnetic shunt or a means of
adjusting the position of the whole
element radially with respect to the
disk.
3.8. DETENTS. A detent or ratchet is
sometimes attached to meters to prevent
rotation in a reverse direction when it is
desired not to register reverse power
flow. This usually consists of a collar
having notches or pins which is placed
on the disk shaft and a pawl attached to
some fixed part of the meter which
engages the notches or pins upon
Figure 5. Magnetic shunt method of adjusting reverse rotation but slides easily over
speed of disk. them in the forward direction. The slight
(FIST 3-10 1/92) 6
amount of friction introduced by the the worm or pinion on the rotating
installation of a ratchet may affect the disk element, for one revolution of
light-load registration and require that the the first dial pointer.
meter be readjusted.
The gear or register ratio is often
3.9. METER CONSTANTS. A knowledge found marked on the rear plate of the
of register and gear ratios and of watt- register or on the gear train frame. In
hour and register constants is required in checking the register and gear ratios,
order to check the correctness of kilowatt- it will probably be found most
hours as read from the register. (See also practical to determine the register
Paragraph 3.11 .) ratio by counting the number of
revolutions that the wheel meshing
3.9.1. Watt-hour constant (Kh). The with the shaft must make for, say,
watt-hour constant is the registration of one-tenth revolution of the first dial
one revolution of the rotating disk pointer. By counting the teeth on this
element expressed in watt-hours. The wheel and the number of teeth on the
watt-hour constant is also sometimes shaft pinion, the "first reduction" is
called the disk constant. The Kh will determine. Register ratio times "first
usually be found marked on the meter reduction" equals gear ratio. In the
nameplate or on the rim of the disk. case of worm on the shaft, the lead
Values of secondary Kh (see or number of threads on the worm
Paragraph 3.10) (per 5-ampere, 115 should be observed to determine how
volt element) commonly used by many teeth the meshing wheel is
various manufacturers for transformer- advanced by one revolution of the
rated meters are listed below. Some shaft.
other values that may be encountered
are listed in parentheses. 3.9.4. Register constant (Kr). - The
register constant is a factor by which
Values of Secondary Kh the register reading is multiplied to
ascertain the number of kilowatt-
General Electric 0.7, 0.9, 1.2, 1,8 (0.3, 1/4)
hours recorded by the meter. The
Westinghouse . . . . . . . . . 1/3, 0.9, 1.8(1/4)
Sangamo . . . . . 0.6, 0.9, 1.2, 1.8(1/3,5/24) register constant is also sometimes
Duncan . . . . . . . . . . . . . . . . . . 0.9, 1.2, 1.8 called the dial constant or multiplier.
The register constant may be 1, 10,
3.9.2. Gear ratio (Rg). - The gear ratio 100, or some integral of 10, except
of a meter is the number of revolutions that for meters used with instrument
of the rotating disk element for one transformers, it may be the register
revolution of the first dial pointer. constant of the meter alone, multi
plied by the product of the ratios of
3.9.3. Register ratio (Rr). - The register the instrument transformers. The
ratio of a meter is the number of register constant is usually marked
revolutions of the wheel meshing with
7 (FIST 3-10 1/92)
on the dial face and may or may not One revolution of the rotating disk ele
take into account the instrument ment of the meter is equal to Kh watt-
transformer ratios. Registers should be hours. The number of revolutions of the
standardized as much as possible to rotating disk element for one revolution
eliminate the stocking of spares. of the first dial pointer is equal to the
gear ratio, Rg, and therefore one
3.10 PRIMARY VERSUS SECONDARY revolution of the first dial pointer will
CONSTANTS. At this point, a word of represent:
caution is in order. If the meter were rated
for use with instrument transformers, as Kh x Rg watt-hours, or
indicated by data on the nameplate, the
watt-hour constant (Kh) and register Kh x Rg
constant (Kr) as marked on the meter or kilowatt-hours.
1,000
nameplate may be "primary constants" and
include the product of the instrument
transformer ratios. If this is the case, it will The numerical value of one revolution of
be obvious, because the Kh will be much the first dial pointer of a standard register
greater than the 1/3, 1/2, 2/3, 0.6, etc., is 10; therefore the register constant for
which is the basic or "secondary" Kh of the kilowatt-hours is:
meter itself. As stated in the first part of this
bulletin, discussion is based on 5-ampere Kh x Rg
Kr =
meters. In the case of 15- or 50-ampere 10 x 1,000
meters, such as might be found in
Government camp service, the "secondary" and
Kh would be large. It is also possible that
installations will be found where meters are
Kr x 10,000
operating with instrument transformers of Rg =
different ratios than originally intended. For Kh
this reason, when checking it is
recommended that the meter be considered First determine the ratio of reduction
separately (as if it were not used with between the shaft of the rotating disk
instrument transformers), and its constants element and the shaft of the gear en
be determined. Then in the last step gaging with it. This is called the "first
checking the register constant - bring in the reduction." Next determine the register
factor of instrument transformer ratios. ratio, Rr, (Paragraph 3.9.3). The gear
ratio, Rg, is equal to the register ratio
3.11. FORMULAS FOR CONSTANTS. To multiplied by the first reduction, and its
recapitulate the foregoing in a different value may be substituted in the equation.
manner, and in a sequencewhich can be In this checking process, it is
used in a checking procedure, and also to recommended that the secondary Kh of
present a useful equation, the following the meter be used, and the Kr of the
procedure is suggested. meter alone be determined first, and
then multiply it by the transformer ratios
(FIST 3-10 1/92) 8
to find the factor (multiplier) by which the meter terminal arrangements shown in
dial reading must be multiplied for the figures were chosen solely for sim
correct measurement of kilowatt-hours. plicity and clarity. Actual arrangement
of terminal studs varies widely with
3.12. BASE-LOAD SPEED. Another make and model. One thing they all
useful characteristic of the meter, if have in common, however, is symmetry,
known, is the base-load speed. Base and it is usually quite easy to trace
icad speed is rpm at 115 volts and 5 (or the internal meter connections to de
2-1/2) amperes, unity power factor. On a termine the identify of studs. For
steady load, by timing the meter speed example, in the case of a 2-element
with a stopwatch, a very accurate value meter with horizontal stud arrange
of kilowatt Icad may be obtained in the ments, the two phases are separated by
absence of a wattmeter; or the same an imaginary horizontal line through the
method may be used to check the center of the meter, and for the sake of
accuracy of an indicating wattmeter. symmetry the voltage studs may be at
(See Paragraph 4.1.4.) Base-load extreme top and bottom. In some
speeds commonly used by various installations the instrument transformers
manufacturers follow, but should not be may supply other instruments besides
construed as applying in all cases. For the watt-hour meters.
example, Westinghouse also uses a
speed of 33-1/3 rpm in their Type CA-8 IV. METERING POWER IN 3-PHASE
meter. CIRCUITS
Base-load speeds - 500 ('or 250) watts/element 4.1. METHODS FOR METERING 3-
General Electric . . . . . . . . . 16-2/3 rpm
PHASE POWER. Four methods are in
Westinghouse . . . . . . . . . . . . . 25 rpm
Sangamo . . . . . . . . . . . . . . 16-2/3 rpm
general use for metering the power or
Duncan . . . . . . . . . . . . . . . . . . . 25 rpm
energy in 3-phase circuits. Each has its
particular application, depending on
Kh and base-load speed are related as whether the circuit is 3- or 4-wire, and
follows for single phase: whether inaccuracy due to unbalanced
currents or voltages can be tolerated.
Nominal volts (115) x nominal amps (5 or 2 - 1/ 2)
Kh =
Base - load speed (rpm) x 60
Each of the four methods is described
in more detail in the following para
graphs. Although each description
3.13. METER CONNECTION DIA refers particularly to watt indication, it is
GRAMS. Figures 6 through 14 also applicable watt-hour metering.
illustrate typical meter connections.
Not all possible meter types are in It is always possible to measure the
cluded, but it is believed that in power in any circuit by using one in
Reclamation powerplants, substa strument or element less than there
tions, and pumping plants, instances are lines or paths in the circuit. This is
where other types of meters are en known as Blondel's Theorem, or the
countered will be extremely rare. The
9 (FIST 3-10 1/92)
(FIST 3-10 1/92)
10
Figure 12. Three-phase, 4-wire, 2-1/1-element meter, three current transformers and two potential transformers.
11 (FIST 3-10 1/92)
Figure 14. Three-phase, 4-wire, 2-1/1-element meter, three element meter.
(FIST 3-10 1/92) 12
(n -1) wattmeter rule. This is shown in one element becomes zero, and below
the following tabulation: 50-per-cent power factor it reverses.
Number Meter elements 4.1.1.1. 2-element Meter, Basic
Type of circuit of lines required Formulas. Referring to Figure 11, the
Single phase 2 1 upper element measures:
3-phase, 3-wire, (delta) 3 2
3-phase, 4-wire (wye) 4 3
P1 = Eab la cos (30 + i)
(Eab is reversed from its
symmetrical order.);
4.1.1. 2-element meters. - The 2-
element-type meter is designed to
the lower element measures:
operate from current in two of the
three phases and the potential be
tween the two phases, as shown in P2 = Ebc lc cos (30 - i);
Figures 10 and 11. It is the most
universally used 3-phase meter con and the total power measured is:
nection, and it is recommended for
ungrounded delta-connected circuits P = P1 +P2 =
only, although applicable to all 3 [Eab la COS (30 + i)] +
phase, 3-wire ungrounded circuits
and to 4-wire or grounded circuits if [Ebc lc COS (30 - i)].
no load is connected between a
phase wire and the neutral or ground. The above formula is applicable to any
The connection is the same as used condition of unbalanced voltage and
on the 2- wattmeter method of power current. For normal balanced
measurement, and is theoretically as conditions, the formula can be simplified
accurate as the 3-wattmeter or 3 by assuming:
element method when used on 3
phase, 3-wire systems. However, the Eab = Ebc = E
power factor and resulting torque on
the two elements is always different, and
and therefore the two elements must
be accurately compensated for la = lc = I.
power-factor errors over the full
range of leading and lagging power And since
factors over which the meter will be
operated. For example, at a load Cos (30 + i) = cos 30 cos i
power factor of 96-percent lagging
- sin 30 sin i
(15E), the power factor on one
element of the meter will be 96 and
percent (15E) lead while the other is
70-percent (45E) lag, as shown in Cos (30 - i) = cos 30 cos i
Figure 11. At a load power factor + sin 30 sin i,
of 50-percent lagging, the torque on
13 (FIST 3-10 1/92)
in adding the two quantities, the term "sin 4.1.1.3. 2-element Meter with Delta-
30 sin i" cancels out. connected Current Transformers. The
2-element meter with delta-connected
Therefore, current transformers is designed to use
the standard 2-element meter operated
from current transformers in each of the
P = P1 + P2 = 2 El cos 30 cos i three phases, which are connected in
delta, and potential transformers
Cos 30 = .866 connected between two of the phases
and neutral or the third phase wire in
P = 2 x .866 El cos i = 1.73 El cos i which no current transformer is installed
as shown in Figure 13. It is applicable to
metering 3-phase, 4-wire or grounded
= 3 El cos i neutral circuits. It is equivalent in the
source and amount of errors to the 2-
which is the basic formula for total power 1/2-element metering method described
in a 3-phase circuit. in Paragraphs 4.1.2. and 4.1.2.1.
Whereas the 2-1/2 element meter
4.1.1.2. Checking Power Factor with 2 obtains the vector sum of the flux of two
element Meter. The power factor of the current coils within the meter, the 2
load being measured can be determined element meter with delta-connected
by the ratio of the readings of the two current transformers obtains the vector
wattmeter elements, when using the 2 sum of two currents by means of the
element wattmeter method. When using delta connection and passes this cur
two separate single-phase wattmeters, rent through the meter coils, the
the power factor is obtained by the ratio resultant effect of the two methods
of the two wattmeter readings P1 and P2 being identical. The B-phase voltage is
from the curve in Figure 15. When using not measured, as shown in Figure 13,
a 2-element watt-hour meter, the potential and is therefore subject to the same
circuit to one element at a time should be errors due to unbalanced voltages as
opened and the revolutions of the disk those encountered in the 2-1/2-element
counted for a definite time period. The meter. This method is also
power factor is then obtained from the objectionable because of the delta
ratio of the disk revolutions for the two connection of current transformers,
readings. The load must of course be which makes the current circuits
constant while the readings are taken. unsuitable for some relays and
Referring to Figure 15, the upper half of instruments which may be used in the
the graph is used when both readings are same circuit, and the secondary circuit
in the same direction (positive), and the current is 8.66 amperes at full-current
lower half when one of the readings is
reversed (negative).
(FIST 3-10 1/92) 14
Figure 15
15 (FIST 3-10 1/92)
transformer rating instead of the usual 5 voltage on one element and with the
amperes. The formulas given for the 2- C-phase voltage on the other. This is
1/2-element meter also apply to this equivalent to using the B-phase
meter and the vector diagram, Figure 13. current with the B-phase voltage,
Relays and other instruments are not nor since the B-phase voltage under
mally permitted to be connected to single balanced voltage conditions is equal
secondary current transformers or to the vector sum of the A- and C-
potential transformers installed for phase voltages reversed. It is
metering purposes. The burden on therefore obvious that the meter will
metering transformers should be kept as not indicate accurately when the
low as possible to accomplish satisfactory voltages are unbalanced so that the B-
metering accuracy. phase voltage reversed is not equal to
the vector sum of the A- and C-phase
4.1.2. 2-1/2-element meters. - The 2-1/2- voltages. The accuracy is not affected
element watt-hour meter is designed to by unbalanced currents, since all three
operate from current transformers in each currents are measured. The upper
of the three phases and potential element measures:
transformers connected between two of
the phases and neutral, as shown in P1 = Eao la cos i + Eao [lb cos (60 - i)].
Figure 12. It is a substitute for the 3
element meters used for metering 3 (lb is reversed from its
phase, 4-wire or grounded neutral circuits symmetrical order.)
where it is desired to save the expense of
the extra potential transformer, which may The lower element measures:
be a considerable item on high-voltage
circuits. However, it is not equivalent in
accuracy to the 3-element meter, P2 = Eco lc cos i + Eco [lb cos (60 + i)].
particularly when the voltage is un
balanced, because the voltage of one of P = P1 + P2 = Eao la cos O + Eao
the phases is not measured. Its use on [lb cos (60 - i)] + Eco lc cos i
permanent Reclamation power circuits is + Eco [lb cos (60 + i)].
not recommended because of its possible
inaccuracy and because it is more difficult Reversing the leads in the meter
to test and adjust than a 3-element meter. causes lb to be read positively and all
units of power can be added as
4.1.2.1. 2-1/2-element Meter, Basic positive numbers. Assuming balanced
Formulas. Referring to Figure 12, currents and voltages,
since the B-phase potential is
missing, the B-phase energy is Eao = Ebo = Eco = E
measured by using the B-phase
current reversed with the A-phase
(FIST 3-10 1/92) 16
and remain 120O apart in phase
relation.
la = lb = lc = I. Thus for an unbalance in voltage
of
And since 10 percent, the metering error will
be
Cos (60 + i) = cos 60 cos i - sin 60 sin i,
10
= 3-1/3 percent.
Cos (60 - i) = cos 60 cos i + sin 60 sin i, 3
and
4.1.3. 3-element meters. - The 3-element
Cos 60 = 0.5, type meter is designed to operate from a
current transformer in each of the three
P = 3 El cos i in terms of line-to-neutral phases and a potential transformer
voltages, connected between each phase and the
neutral or ground, as shown in Figure 14.
or It is applicable to 3-phase, 4-wire or
grounded neutral circuits. Its accuracy is
3 El cos ˘ independent of all conditions of
P= = 1.73 El cos i
1.73 unbalanced currents and voltages and
varying power factor. It is essentially three
in terms of line-to-line voltages, single-phase elements mounted on one
which is the basic formula for power shaft so that their torques can be totalized.
in a 3-phase circuit. Each element operates at the same power
factor as the metered load for all
The meter torque due to conditions. Special transformers may be
required when used with delta-connected
Eao [lb cos (60 - i)] + Eco [lb cos (60 + i)], loads.
4.1.3.1. 3-element Meter, Basic
which is the portion affected by
Formulas. Referring to Figure 14, the
unbalanced voltage, is always one-
energy measured by each element is
third of the total torque for balanced
as follows:
conditions. The error in metering due
to unbalanced voltages is therefore:
Pa = Eao la cos i,
Percent unbalanced in voltage
Percent error =
3
Pb = Ebo lb cos i,
The unbalance in voltage equals the
difference between the voltage of the
unmeasured phase and the vector Pc = Eco lc cos i, and
sum of the other two voltages.
It is assumed that the three voltages
17 (FIST 3-10 1/92)
P = Pa+ Pb + Pc = Eao la Kh = Watt-hour constant marked
cos i + Ebo lc cos i + Eco lc on rim of disk or on nameplate (see
Paragraphs 3.9.1, 3.10, and 3.12)
cos i, which is applicable to
all conditions of unbalance.
S = Seconds duration of test,
Assume the usual condition
where the voltages and
R = Revolutions of disk in Time S.
currents are balanced,
Obviously, for such measurements
the load must remain constant over
Eao = Ebo = Eco = E, the test period. Otherwise the
reading obtained will be the average
and watts over the time period used.
la = lb = Ic - I. V. METERING VARS AND VOLT-
AMPERES
P = 3 EI cos i,
5.1. GENERAL. In the following para
in terms of line current and line-to- graphs reference to measurement of
neutral voltage, or vars and volt-amperes by indicating or
recording instruments also applies
3 EI cos ˘ equally well to registration of varhours
P= = 1.73 El cos i, and volt-ampere-hours, respectively, by
1.73
integrating meters.
In terms of line current and line-to-line
5.2. VAR METERING. Vars (reactive
voltage, which is the basic formula for
volt-amperes) can be measured on
total power in a 3-phase circuit.
standard indicating or recording watt
meters, provided the potentials applied
4.1.4. Measuring watts with a watt-hour
to the instrument coils are shifted 90O
meter. - The load on a circuit, in watts, can
from the position used for measuring
be found from any watt-hour meter by
watts. This is due to the fact that watts
taking a reading of the time in seconds, re
and vars are at right angles to each
quired for the disk to make a given number
other in vector relation. For single-
of revolutions, from which
phase circuits, the 90O phase shift is
usually accomplished by connecting a
3,600 Kh R capacitor-resistor combination in the
P=
S meter coil potential circuit, as shown in
Figure 16.
where
For balanced 3-phase circuits, the vars
P = Power in watts, can be measured by one instrument
using the current in one phase and the
(FIST 3-10 1/92) 18
voltage. Since the phase-to-phase voltage
used above is 1.73 times the phase-to-
neutral value, the total 3-phase vars for the
above condition will be single-element
3
reading times or 1.73.
1.73
The usual varmeters for 3-phase circuits
have two or three elements, the same as
wattmeters. The quadrature (90O) potential
required can be obtained either by using a
Figure 16. Single-phase varmeter. cross-phase connection as described
above for the single-element method, or
potential between opposite phases; that is, with a phase-shifting autotransformer. Re
Phase C current with Phase AB voltage, ferring to Figure 11, the cross-phase
as shown in Figure 17. The total vars in method would use Currant la with Potential
the 3-phase circuit is three times the Ebc on one element, the Current lc with
single-phase value, keeping in mind that Potential Eab on the other element. A third
the single-phase value implies using element could be connected in a similar
phase current and phase-to- neutral manner. This method is merely two or three
Figure 17. Varmeter for balanced three-phase circuit.
19 (FIST 3-10 1/92)
of the Figure 17 elements combined. At
l00-percent power-factor load, the current
and voltage on both elements will be 90O
out of phase. The sum of the readings of
1.73
two elements must be multiplied by
2
or .866, or the sum of
.
173
the readings of three elements by or
3
.576, to obtain total 3-phase 3 vars. The 2
element method is accurate only on
balanced 3-phase circuits, but the 3
element method is accurate for all
conditions of unbalanced currents and
voltages.
Connections for a 2-element meter having
a phase-shifting autotransformer are
shown in Figure 18. Autotransformers of
various types and connections are Figure 18. Three-phase varmeter using
available for use with other types of autotransformers
circuits and meters. It should be noted that
the autotransformer method shifts the At 100-percent power-factor load on the
potential that would normally be used for circuit the varmeter will read zero, and the
watt indication by 90O, and maintains the reading will be on the opposite side of zero
same magnitude of voltage on the meter for leading and lagging power-factor loads.
coil. Therefore, no different multiplier is It is customary to make indicating and
needed than that which would be used for recording var-meters with zero center
reading watts in the same circuit, and the scales so that indication can be obtained
varmeter calibration will be the same as for for loads of either leading or lagging power
reading watts, whereas with the cross- factors. In the case of integrating
phase method a multiplier of .866 must be varmeters, two meters, each with ratchets,
used. At 100-percent power-factor load, would be necessary if registration for both
the current and voltage are 60O out of leading and lagging power-factor con
phase on one element and 120O out of ditions is required. Furthermore, if power
phase on the other element. The 2 can flow in either direction through the
element meter is accurate for all circuit, four var-hour meters with special
conditions of unbalanced currents and provisions to prevent reverse rotation
voltages for a 3-phase, 3-wire circuit, for would be required to properly register for
the same reason that applies to the 2 the four conditions; that is: lagging power
element wattmeter method.
(FIST 3-10 1/92) 20
flowing in, lagging power flowing out, Angle, in
leading power flowing in, and leading degrees Cosine
power flowing out.
0 1.0000
5.3. VOLT-AMPERE METERING. In 1 .9998
struments and meters with certain 2 .9994
3 .9986
accuracy limitations are available for
4 .9976
indicating, recording, or registering volt- 5 .9962
amperes and volt-ampere hours. 6 .9945
7 .9925
As an alternate to metering volt-amperes 8 .9903
on a direct reading instrument, watts and 9 .9877
vars may be measured separately and 10 .9848
the volt-amperes determined by 11 .9816
calculation from the formula: 11.5 .9799
va = watts 2 + vars 2 For example, if the meter were designed
for a 90-percent power-factor load, the
The self-contained volt-ampere meter registration would be within 1-percent
utilizes a wattmeter in which the voltage is accuracy between 83.1- and 95.6- percent
displaced by an angle corresponding to power factor and exact at 90-percent
the average power factor of the load. The power factor.
phase shift in the voltage is ordinarily
obtained by the use of an The permissible range of load power factor
autotransformer. Such a meter will can be further extended by setting the
register accurately only when the load meter 1 percent fast at 90-percent power
power factor corresponds to the average factor in which case the registration will be
power factor for which the meter is within plus-or-minus 1 percent over a
designed, but the accuracy will decrease range of about +11.5O or from 79.5- to
for power factors on either side of the 96.9-percent power factor. The satisfactory
design value. However, the power factor application of this metering method will
can vary over an appreciable range depend on the accuracy required and the
without causing an intolerable error, since range of average power factor for the
the cosine of the phase angle changes particular load involved. When using this
only about 1 percent for angles up to 8O metering method, a periodic check of the
as shown in the following table: load power factor should be made at
reasonable intervals to see that the power
factor is still within the range for which the
meter is connected.
21 (FIST 3-10 1/92)
The above is known as the displaced Percent
voltage method of measuring volt-ampere At rated voltage and registration
hours and consists of using a watt-hour frequency
meter in which the voltage has been
Unity power factor, 100%
shifted to an angle corresponding to the current 99.7 to 100.3
load power factor so as to be in phase Unity power factor, 10%
with the line current yet equal in current 99.7 to 100.3
magnitude to the original circuit voltage. Unity power factor, 50%
Thus, the power factor in the meter is current 99.7 to 100.3
50% lagging power factor,
unity and the registration of the meter will 100% current 99.3 to 100.7
be proportional to volt-ampere hours over
a limited range of power factor.
n the recording of meter accuracy, the term
This metering method and the accuracy "percent registration" is used rather than
considerations involved are discussed in "percent error."
Chapter 9 of the Electrical Metermen's
Handbook. actual registration kWh x 100
% registration =
true kWh
Although ANSI Standards C12-1965
Paragraph 8.1.3.4 restricts the allowable The above accuracy limits apply to each
registration error to 1 percent at unit element of a polyphase meter and to the
power factor for light and heavy load and combination of all elements when tested on
2 percent at 0.5 power factor lag, much a single phase with the current coils in
closer tolerances can and should be series.
maintained.
6.2. INSTRUMENT TRANSFORMER
ERRORS. Meters used with instrument
VI. ERRORS IN WATT-HOUR transformers can be calibrated to
METERING compensate for the errors of the trans
formers, but with high-accuracy instrument
6.1 METER ACCURACY. The watt-hour transformers operated within their ratings
meter is a precise instrument capable of (burden), the error is small and usually
adjustment within very close limits and neglected. If necessary, the correction factor
with periodic servicing will maintain such (Kf) for ratio and phase-angle errors may be
accuracy indefinitely. As a Reclamation determined from the following if the required
standard, meters should be adjusted data are available on the instrument
within the following limits: transformers:
Kf = CV Kp
where:
(FIST 3-10 1/92) 22
Actual transformer ratio inspection and corrected.
C=
Marked transformer ratio
6.3.1. Common causes. -
(current transformer):
(1) Dirt (on the disk; in the air
Actual transformer ratio gaps).
V=
Marked transformer ratio
(potential transformer): (2) Magnetic particles (in the per-
manent-magnet air gaps).
Kp = Phase-angle correction factor
for combined potential and (3) Gummy oil and/or dirt in bear-
current transformers ings.
Cos (˘ + B - Y (4) Broken jewels.
=
Cos ˘ 2
(5) Disk rubbing in air gap.
in which
(6) Improper mesh of gears or dirty
gearing.
Cos i2 = Apparent power factor of
load as measured on the (7) Improperly adjusted bearings.
secondary of the transformers;
(8) Vibration of the meter mount-
B = Angle by which the re ing.
versed secondary current
leads the primary current; (9) Creeping.
Y = Angle by which the re With the exception of (8) and (9)
versed secondary voltage above, it will be noted that all
leads the primary voltage. defects listed introduce friction and
will cause the meter to register
In using this formula, care must be taken "slow."
to use the proper sign with B and Y.
Information is available in the Code for 6.3.2. Other causes. -
Electricity Metering from which Kp may be
readily obtained, without carrying out the (1) External magnetic fields which
detailed calculations of the formula. may add to, or subtract from, the
normal meter magnetic flux.
6.3 SOURCES OF METER ERRORS.
Aside from the inherent errors due to (2) Overloads and short circuits. The
variations in temperature, frequency, etc., effect of overloads and short circuits
which are factors of design, the most may be to alter the magnetization of
common causes of error within a meter the brake magnets,
are listed below and may be detected by
23 (FIST 3-10 1/92)
to magnetize adjacent masses of without damage to them. Short-circuiting
iron, and in general to disarrange loaded current transformer secondaries
the parts. with jumpers having test clips on the
ends should be avoided whenever
(3) Short-circuited turns in meter possible. If such connections are
coils. insecure, the test man and current
transformer may be exposed to the high
6.3.3. External causes. - Some of the voltages that will result if the jumper
sources of error which may occur becomes dislodged or is inadvertently
outside the meter itself are: disconnected while changing test
connections.
(1) Instrument transformer phase-
angle and ratio errors. Before connecting to a meter to be
tested, check to insure that all wiring
(2) Improper connections such as from the instrument transformers has
cross-phasing and reversed been disconnected at the meter, or that
polarity. the meter has been isolated by other
means such as test jacks or test
(3) Broken or high-resistance terminals. Make certain in particular that
connections and short circuits in no ground connection remains
meter wiring and test blocks, blown connected to any of the meter circuits,
potential fuses, short-circuiting since undoubtedly one or both sides if
switches inadvertently closed or left the circuit used to supply test power will
closed, etc. be "hot" with respect to ground. As
mentioned in Paragraph 7.2 below, a
(4) Improperly calibrated or poorly hand potential switch and leads should
maintained rotating standards. be available for the standard watt-hour
meter (rotating standard), as well as a
VII. METER TEST EQUIPMENT AND fused switch for the supply.
CONNECTIONS
All test connections should be made in a
7.1 TEST LEADS AND CONNEC safe manner, taking care to avoid
TIONS. Since routine tests are accidental contact with any other con
required at least annually, and in the nections or equipment on the
interests of safety and saving time, it is switchboard. Leads and test equipment
recommended that suitable and con should be arranged and located so as to
venient test leads and jumpers be avoid the possibility of anyone tripping
made up and kept on hand solely for over them, and so as to avoid
meter testing. In case it is advanta interference with normal or emergency
geous or necessary to use test clips duties of the operators.
instead of spade lugs on the wires, the
clips should be insulated and capable 7.2. PORTABLE STANDARD WATT-
of gripping the meter studs, terminals, HOUR METER. The portable standard
or other test-connection points securely
(FIST 3-10 1/92) 24
watt-hour meter, sometimes called a
"rotating standard," is merely a
precision-built and calibrated portable
single-phase watt-hour meter. A pointer
attached to the disk shaft enables
accurate reading on a 100-division
scale. A smaller pointer totals the
revolutions of the larger pointer. A reset
knob or button is provided to set all
pointers to zero. For flexibility, various
current and potential ranges are usually
incorporated. Polyphase standards are
commercially available, but a single-
phase standard is sufficient for all
ordinary purposes. A special hand
switch, which operates in the potential
circuit of the standard, enhances the
accuracy of starting and stopping the
standard and is considered an essential
accessory.
7.3. LOADING DEVICES. The circuit Figure 19. Testing both elements of a meter using
load may be used if it can be controlled resistance load.
to obtain the various test conditions
required. However, this is not usually current is controlled by a built-in rheostat. A
the case, and artificial current loading very convenient feature incorporated in some
devices are generally used. Two are in phantom loads is a provision for 50-percent
common use. lagging power factor. See Figure 20.
7.3.1. Resistance load. - A resistance A real difficulty with resistance loading lies in
box with taps controlled by switches to the problem of dissipating the energy
vary the current is used in series with consumed by the high 12R loss at high
the current coils of the meter to adjust currents. For more details of this problem, see
the current drawn from a 115-volt or Chapter 15 of the Electrical Metermen's
230-volt source. See Figure 19. Handbook.
7.3.2. Transformer load. - The The resistance load is preferred when test
transformer load is sometimes called a currents are light, since the current in the
"phantom" load. This device is a current coil is assured of being in phase with
stepdown transformer supplying a low the potential coil, and no waveform distortion is
voltage from a 115- or 230-volt source introduced. Furthermore, in the case of meters
to operate the meter current coils. The
25 (FIST 3-10 1/92)
hour meters under test. The most
convenient style is a jack into which a
plug carrying test connections may be
inserted. The insertion of this plug opens
the potential transformer circuits and
shorts the current transformer circuits,
leaving the meter isolated from the
instrument transformers and connected to
the test equipment. The terminal block
style is provided with switches or links to
accomplish the same, and the terminals
afford a convenient means of making test
connections. At older installations,
bridging jumpers and test connections will
have to be applied wherever most
convenient.
Some switchboard-type watt-hour meters
Figure 20. Testing one element of a meter using are equipped with internal links and
phantom load device. screws for test connections. The following
equipment should be provided for testing
used with instrument transformers and watt-hour meters in the field.
having 2.5- or 5-ampere current coils,
there is not much advantage in using a 7.4.1. Test equipment required. -
phantom load; the main advantage of
phantom loads is realized when they are (1) Rotating standard with potential switch
used with meters requiring heavy test and leads
currents. Another reason for the choice of
resistance loading is that resistance load (2) Load device - Resistance box,
boxes are generally used in relay testing adjustable resistors, or phantom load
to assure freedom from wave distortion,
and thus can serve double duty. A well- (3) Ammeter(s) of suitable ranges (not
designed phantom load, as sold by absolutely necessary when using
leading manufacturers of meter-testing resistance box or phantom load calibrated
equipment is, however, an acceptable in amperes)
load for watt-hour meter testing.
(4) Power-factor meter (not necessary,
7.4. METER TEST BLOCKS. Modern but very convenient not only for reading
Reclamation installations provide a test power factor but
jack or terminal block for convenience
and safety in making connections to watt-
(FIST 3-10 1/92) 26
also for checking phase relation connections, and determine whether the
ships) test connections are in error or whether
an internal connection of the meter has
(5) Voltmeter (not necessary, but been changed. If such a condition is
useful in checking connections) found, it will, of course, affect the sketch
made in verifying the physical
(6) Phase-sequence indicator connections (Paragraph 8.1), and may
(see Figure 21) explain an apparent discrepancy found
at that time.
(7) Power supply switch, fused
7.6. TEST SUPPLY SOURCES. In using
(8) Test leads and jumpers a resistance box for loading, observe the
voltage for which the box was designed.
(9) Tools for cleaning, jewel and A 115-volt box cannot be used on 230
pivot wrenches, etc. volts without adding resistance
externally. A 230-volt box can be used
(10) Jewel oil on 115 volts, but the current range and
steps will be halved. The same
7.5. ERRORS DUE TO IMPROPER precaution also applies to phantom-load
TEST CONNECTIONS. In connecting up devices, although many are designed for
for test, each hookup should be checked dual voltage. Obviously, also, the voltage
to see that no connection has been made of the supply for the potential coils of the
that will result in erroneous standard and meter under test must be
measurements. The current drawn by appropriate. It is not necessary,
potential coils or the phantom-load device however, that the supply used for the
primary should not pass through any current circuit be the same as that for the
current coil; the same load current should potential coils; 230 volts may be used for
pass through all current coils; and the the current-circuit if the loading device is
same voltage should be applied to all designed for that voltage. In the case of
potential coils. The above conditions are dual supply sources, care must be taken
easily satisfied by making sure that all to choose the same phase of each
potential connections (and phantom- load source. For this reason, it is usually
primary if used) are connected to the better to use a common supply to avoid
supply ahead of the resistance box and errors and simplify checking
meter current coils; and that all current connections.
coils are connected in series. Refer to
Figure 19, 20, and 22 for examples. 7.7. TEST CONNECTION DIAGRAMS.
Test connection diagrams, Figures 19,
If symmetrical test connections to the 20, and 22, show methods of connecting
meter should result in one element run the rotating standard and different types
ning reversed, do not simply reverse of load devices to various types of
connections to a coil of that element and meters.
proceed. Stop, recheck the test
27 (FIST 3-10 1/92)
Figure 21. Phase sequence indicators.
(FIST 3-10 1/92) 28
7.8. TESTS AT 50-PERCENT POWER from 3-1, current from 3-2.
FACTOR. The test at 50-percent lag
ging power factor is most conveniently When sequence is 3-2-1: Use potential
performed when a phantom load with from 2-1, current from 2-3, or potential
this feature is available. However, if a from 1-3, current from 1-2, or potential
115-volt, 3-phase supply is available from 3-2, current from 3-1.
and the phase sequence is known, the
50-percent power factor test may be Figure 21 shows three methods of de
made as follows: termining phase sequence with
apparatus that can be assembled on the
When sequence is 1-2-3: Use potential project. Inexpensive indicators are also
from 1-2, current from 1-3, or potential available commercially.
from 2-3, current from 2-1, or potential
Figure 22. Testing single-phase meter using
customer’s load.
29 (FIST 3-10 1/92)
VIII. PRETEST CHECKING transformer which is in service. Very
high voltages are developed which
8.1. VERIFICATION OF METER are not only a hazard to life, but may
CONNECTIONS. In 3-phase metering damage the transformer and/or
with instrument transformers, the affect its accuracy.
possibilities of wrong connections are
many; obviously the meter registration 8.1.1. Checking wiring. - Wires in
will be false unless all connections are conduit, after being tagged and dis
correct. It is, therefore, of utmost connected at both ends, can be
importance that the wiring be checked traced or "rung" using a battery and
against the Denver drawing for the in buzzer, ohmmeter, magneto, test
stallation, the manufacturer's lamp, etc., if the wires are not color-
instruction book, or other appropriate coded for identification. Do not use
diagram. When instrument transform a 1,000- or 2,500- volt insulation
ers are used, the best check method resistance meter as insulation may
is a physical tracing of wiring and be damaged.
making a sketch of the connections.
Before taking a meter out of service, Connections of the instrument trans
be sure to make a record of the time, formers in the power circuit should
meter reading, and the disk speed of be checked, noting the polarity. Po
the meter. larity markings are conventionally
white and may be paint or white
CAUTION: Observe all safety precau porcelain buttons. The terminals
tions in working around live circuits. It may also be marked H1 and X1 to
is preferable to obtain a clearance if denote polarity; e.g., at any instant,
the instrument transformers must be if current is entering at H1, it will be
worked on. The potential transformer leaving at X1. Although cases of
secondary circuit should be opened at incorrect polarity marking of instru
test blocks or fuses, where provided. ment transformers have been found,
Never open any part of the secondary the polarity can be assumed correct.
circuit of current transformers which
are carrying load current until a secure After the sketch of the wiring as
short circuit has been placed across found has been made, it should be
the secondary terminals. Some of the compared with the Denver drawing
older current transformers are not pro or the appropriate diagram in this
vided with a terminal strip having an bulletin, noting carefully every con
automatic shorting device which oper nection and the polarities of
ates when the terminal-strip cover is transformers. With regard to polarit
removed, and a jumper must be placed ies, if all polarities are reversed, the
across the terminals before discon connection is still correct. Similarly,
necting the wiring. Too great an a proper connection results if all
emphasis cannot be placed on the im connections at the meter are re
portance of being extremely careful not versed. With regard to polarity, or
to open the secondary of a current
(FIST 3-10 1/92) 30
proper direction of connections to will prevent access to the instrument
meter terminals, it should be found that transformers, or for other reasons the
connections to the terminals or studs wiring cannot be physically verified. For
will be symmetrical unless someone these reasons, some expedient checks are
has changed internal meter given that will give fair assurance of
connections. It is not impossible that correct connections. Only simple checks
this condition may be found, since an which can be performed readily are
error in wiring may have been outlined.
corrected by shifting connections within
the meter. 8.1.2.1. Single-phase Meters. No check is
possible except to verify that the meter
direction under all load conditions. This runs in the forward
check will be of most value if a load
condition of less than 50-percent power 8.1.2.2. 3-phase, 4-wire, 3-element
factor can be observed. Only a Meters. (Figure 14). As in the case of
physical check will verify that the meter single-phase meters, checking by simple
is connected to the proper means is limited to observing for proper
transformers, and has not been cross- rotation direction at all load conditions
phased or connected to the wrong (under low power-factor condition if
transformers such as those of another possible), taking each element individually.
phase or circuit.
8.1.2.3. 3-phase, 3-wire, 2-element
8.1.2. Other means of verifying Meters. (Figure 11). An inherent
connections. - In the case of poly characteristic of this metering circuit lends
phase watt-hour meters supplied from itself to checking by means of shifting
instrument transformers, any method connections. On loads having a lagging
of complete checking by changing power factor greater than 50-percent, both
connections at the meter and noting elements rotate forward, whereas on less
results is complicated, and except than 50-percent power factor, one element
when done by an experienced man, is tends to rotate backward, and will do so if
of doubtful certainty. The physical the potential circuit of the other element is
checking of connections outlined above disconnected.
is usually no less laborious, but results
are certain. Therefore, the method of A power factor of 50-percent or less is not
tracing the wiring, sketching con normally encountered in loaded power
nections, and comparing with a correct circuits. Loads such as an induction motor
diagram is strongly recommended in all running with no load or a very light load, or
cases. However, there may be a synchronous motor partly loaded and
occasions where safety considerations underexcited, will draw current at less
31 (FIST 3-10 1/92)
than 50-percent power factor. Also, a fied, the ratios of instrument
generator operated at part load with transformers should be checked
strong excitation (field) can be made to against their nameplates at the time
supply power at less than 50- percent the wiring is being traced. Also, at the
power factor. The following check same time note the capacity and other
procedures are fairly reliable if the load data on the nameplate. If the rated
is reasonably well balanced and the burden (load capacity, which is usually
meter is connected to the proper set of given in volt-amperes) is exceeded by the
instrument transformers: meters, instruments, relays, etc.,
connected to an instrument transformer,
(1) On a load whose power factor the ratio and phase-angle errors may be
is known to be greater than 50 too great for accurate metering purposes.
percent, observe the rotation of In some cases separate instrument
each element while the potential transformers are used for metering
circuit of the other element is dis purposes, and others installed for
connected. If connections are instruments and relays. Cases may be
correct, the rotation will be for found, however, where equipment has
ward on both, but one will be been added since the original installation,
slower than the other, depending and whenever it is suspected that the
on the power factor. Next, ar transformer capacity has been exceeded,
range for a power factor of less the burdens of the connected instruments
than 50-percent in the power cir should be determined from the
cult being metered. The element manufacturers' instruction booklets or
of the meter that was the slower measured by connecting a voltmeter, an
on the test above 50-percent ammeter, and a wattmeter ahead of the
power factor should now rotate in normal burden.
the reverse direction, while the
faster element will still rotate for Ordinarily relays or other instruments are
ward. not permitted to be connected to single
secondary current transformers or
(2) Another check that has been potential transformers installed for
used, but which is not very con metering purposes. The burden on
clusive when instrument trans metering transformers should be kept as
formers are involved, is to reverse low as possible to accomplish satisfactory
potential connections a and c metering accuracy.
(Figure 11) at the meter. If the
meter previously rotated forward, 8.3. CREEP. The disk of a meter may
and rotation ceases after chang move, either forward or backward, when
ing connections, the original con all load is disconnected. A meter in service
nection is presumed correct. is considered to creep when, with all load
wires disconnected, and test voltage
8.2. CHECKING INSTRUMENT applied, the moving element makes one
TRANSFORMER BURDEN. In order
that the meter constants may be veri
(FIST 3-10 1/92) 32
revolution in 10 minutes or less. (ANSI electromagnetic circuit.
Standards, C12-1965.) Meter disks
usually have holes or slots punched in A high-resistance short or ground in the
them to stop creep when the holes or customer's circuit can cause a turning of
slots reach a position directly under the the rotating element which may be
potential coil pole. Observation of creep mistaken for creeping; therefore,
should, therefore, be based upon at least residence wiring should be isolated from
one complete revolution. Creeping may the meter when checking for creep.
be caused by:
Although the definition of creep permits
(1) Light-load adjustment used to one revolution in 10 minutes or less, the
compensate for instead of removing serviceman should persevere in
friction. Examine for friction. If the friction eliminating any tendency of a meter to
has since disappeared, or is found and creep.
eliminated, the meter will be found fast on
light load under test, and the creep will IX. METER SERVICING.
disappear when the meter is adjusted at
light load. 9.1. "AS FOUND" TEST. Before ser
vicing a meter, the "as found" test
(2) Short-circuited turns in potential coil. (Paragraph 10.4) should have been
In this case the meter will be found made with the least disturbance possi
inaccurate at low power factor. Replace ble. The cover should be left in place
coil or entire electromagnet. until this test has been made and re
corded, if it is possible to make the
(3) Vibration. Remove cause of vi- necessary connections without removing
bration. Move meter. the cover.
(4) Stray fields either internal or external. Servicing as discussed herein is defined
as cleaning, along with a mechanical and
(5) Too high voltage which has the same electrical inspection.
effect as overcompensation of light-load
adjustment. 9.2. CLEANING. After the cover has
been removed, it should be cleaned and
(6) The potential circuit being connected a new gasket fitted if needed. In
on the load side of the meter. localities where spiders and other small
insects are present in large quantities, or
(7) Short-circuited turns in current coils. there is much fine dust, it is particularly
Replace coil or entire electromagnet.
(8) Mechanical disarrangement of the
33 (FIST 3-10 1/92)
important that all cracks and openings Jewels crack, balls wear flat, and pivot
be tightly sealed. The interior of the points become rounded excessively these
meter should be thoroughly cleaned of are defects to examine for when
all dust and foreign material. A small inspecting bearings. A cracked or rough
hand bellows and camel's hair brush will jewel may often be detected by feeling
be useful in removing dust. The air gaps the surface of the depression in the
may be inspected while directing a jewel with a sharp sewing needle. This
flashlight beam toward the rear of the method is not recommended because of
meter or onto a piece of white paper danger of scratching the
placed behind the element. Dirt may be
removed from the air gaps by using a Meter Standard
folded piece of paper. Foreign magnetic
particles adhering to the permanent 5 9
magnets may be removed with a thin 10 18
15 27
brass or phosphor bronze magnet 20 36
cleaner having a steel edge or button or or
insert. 5(n) 9(n)
CAUTION: Do not use a magnet where n = any reasonable number.
cleaner such as the above, which has a
magnetic section, in the gaps of Alnico jewel, and should be avoided if a glass of
magnets. Other precautions to observe high magnification is available. If a
in connection with Alnico magnets are reddish powder has formed in a bearing,
to avoid striking them, to never it is certain evidence of trouble.
disassemble or remove the magnets,
and to never bridge the gaps with any Whenever it is necessary to replace a
magnetic material. jewel, the companion pivot (or ball)
should also be replaced because it is sure
9.3. BEARINGS. Bearings should be to have been damaged. Pivots are
disassembled so that all parts can be screwed into the shaft and require a
cleaned and inspected. Special special wrench to remove. Jewels on the
wrenches are usually required for re shaft are usually a slip fit and a special
moving pivots. Corn pith is an aid in tool is very useful in removing and
cleaning pivots. A solvent such as replacing them, though not absolutely
Chlorothene may be required to dis necessary.
solve gummed oil deposits. An
orangewood stick or even a toothpick Care should be exercised in handling
may be used to clean out the top bear balls and pivots to protect them from
ing guide sleeve in the shaft. rusting. If balls or pivots are covered with
a protective grease film, it should not be
Jewels, balls, and pivots are best in removed until just before installation. Use
spected with a microscope or high- tweezers to handle and do not touch with
power jeweler's glass, if available. the fingers. One small drop of jewel (or
high-quality clock) oil should be placed
(FIST 3-10 1/92) 34
in the jewel of the pivot-jewel type of mined accuracy is substantially free
lower bearing. Do not use oil in the of human errors. The test period on
jewel-ball-jewel type. Do not oil top any run should not be less than 30
bearings. When reassembling bottom seconds and the number of runs not
bearings, check the centering of the less than three. More than three runs
disk in the air gap and adjust if should be taken if necessary to deter
needed. The top bearing plug should mine a true average for recording. The
not be lowered so much that its length of run should be longer on light-
shoulder touches the end of the load tests to enable accurate reading
shaft. of the standard, and the meter under
test should make more than one revo
9.4. REGISTERS AND GEARS. Reg lution to minimize starting and stopping
ister faces may be cleaned with a errors. In choosing the length of run, it
damp cloth. Alignment of pointers is often possible to select a number of
should be adjusted if required. The revolutions of the standard that will be
gears may be washed with a solvent convenient in that the accuracy may be
or merely blown out and thoroughly read directly from the standard and not
inspected for foreign particles in the require computation. For instance, 10
teeth as the case may require. Gear revolutions of the standard enables
teeth may be cleaned with a small reading directly (on a 100-division dial)
stiff brush (toothbrush) or a to 0.1 percent and estimating to 0.01
sharpened piece of softwood. Do not percent, 20 revolutions to 0.005
oil registers. Free motion of the percent, etc. Choosing the number of
gearing can be checked by spinning revolutions of the standard in testing
with the fingers. any meter will also be governed by the
watt-hour constants of the standard
When replacing the register in a and the meter under test. If the
meter, the mesh of the first wheel constants are the same or multiples,
with the worm (or pinion) must be there is no problem; but when they are
carefully observed and adjusted. It not, the choice is limited. For example:
should be at the proper height to Assume you are using a standard with
center on the shaft worm (or pinion), Kh = 1/3 and the meter under test has
and must have a loose mesh or a Kh of 0.6; possible test runs that will
"backlash." One-third to one-half the result in integral (whole) revolutions of
depth of the worm (or pinion) teeth is each meter are limited to the following:
a proper mesh - just enough so that
the first wheel cannot be forced to It is, of course, possible to choose any
slip when moved by the fingers. number of revolutions of the meter
under test and compute the corre
X. TEST PROCEDURES AND sponding standard revolutions (to a
ADJUSTMENTS. sufficient number of decimal places to
insure accuracy), but the better plan is
10.1. TEST RUNS. The test period to make a choice that will result in an
should be long enough, and sufficient integral number of revolutions on the
runs made to insure that the deter
35 (FIST 3-10 1/92)
standard, and when possible, choose a Test Current Percent Percent
number which will result in a direct coil current power
accuracy reading, or one involving a connections factor
minimum of calculations. Not only will the lagging)
work be speeded up, but the chances of 1 Series 100 100
arithmetical errors are minimized. 2 Series 100 50
3 Series 10 100
The test cards, commonly furnished with 4 Separately 100 100
standards, which tabulate revolutions 5 Separately 100 50
6 Separately * 100
and percent registration for testing 7 Series 50 100
various manufacturers' meters are very
convenient. The factory calibration data *10 percent for single-element meters, 20
furnished with the standard should be percent for 2-element meters, 30 percent for
examined, and if the accuracy of the test 3-element meters.
requires, allowance for standard errors
can be made. Before making the actual interpreted as an indication of trouble in
runs, load should be applied and the the meter, perhaps of an intermittent
meter under test allowed to run a few nature.
minutes if it has been out of service long
enough to cool appreciably. The 10.2. TEST LOADING. No special
standard also should be given a warmup precautions are necessary when the
run, preferably 30 minutes or longer. load is a resistance box. In the case of
other resistors, they must, if course,
From observation of the marking on the have sufficient current-carrying and
disk and construction of the meter, a adequate ventilation for cooling. In the
definite and precise point in the rotation case of "phantom" or transformer load
of the meter disk should be decided devices, the secondary circuit should
upon at which the standard will be always include resistance that is large
started and stopped by the hand switch. compared to the reactance of the meter
The point where the forward edge of the current coils to avoid waveform and
black mark on the disk enters the phase-angle errors. Phantom-load
magnet after passing through the gap, or devices as marketed by the better-
passes a mark on the magnet frame, is known meter-test-equipment
a common choice. The stationary manufactures are generally satisfactory
reference point or mark should be as in this respect.
close to the disk as possible, and the
operator should try to maintain his eye in 10.3. ADJUSTMENTS, GENERAL. If
the same position during the run so that the "as found" test shows inaccuracy,
parallax error will be a minimum. Very and if the subsequent cleaning and
little practice in the use of the hand mechanical servicing does not remove
switch is required to obtain consistent the errors, it will be necessary to make
and close results. Any undue inconsis adjustments. It may also be found that
tency in readings obtained should be a meter will be inaccurate after servicing
(FIST 3-10 1/92) 36
although the "as found" test did not For the purposes of this discussion, it is
disclose errors - the meter may have assumed that the lag or power-factor
been adjusted to compensate for friction adjustment of each element has been
which has been removed in servicing. checked and found correct, or has been
At this point, it will be helpful to the appropriately adjusted. The lag
tester in diagnosing the adjustments adjustment, if properly made at the
required, and planning the sequence of factory, does not ordinarily change in
making adjustments, to discuss the service. Therefore, no lag adjustments
interrelationship of adjustments. should be made until the tester is
absolutely certain of their need. After
The light-load adjustment alters the making a light-load adjustment on each
driving torque of the meter which must element, the torque of all elements
overcome friction and rotate the disk. should be in fair balance, but at this point
The permanent magnets acting as a the balance should be checked by
brake to regulate the speed is the full- bucking elements as described in
load adjustment. The adjustment of Paragraph 10.5.3.
either affects the speed at both loads.
The effect of the light-load adjustment is It is now in order to make a full-load
inversely proportional to the load; i.e., adjustment at 100-percent current with
one-tenth as much at full load as at light the current coils of all elements in series.
load. The effect of the full-load Next, the overall 50-percent power-factor
adjustment on the percent registration and light-load registration should be
of a meter is the same at all loads; i.e., checked, followed by checks on
if the meter is 3 percent fast at both full individual elements. If lag readjustments
and light loads, adjusting the magnets are necessary, both light and full loads
will correct the registration at both and balance must be rechecked. If only
points. light-load adjustments are necessary,
balance and full load must be rechecked.
Although fairly obvious, it should be Step-by-step test procedure is outlined in
mentioned here that adjusting any the following paragraphs.
magnet in a multielement meter affects
the speed of all elements of the meter, 10.4. "AS FOUND" TEST. Since it is
since the disks are on a common shaft. extremely important to know of any past
In other words, the light-load adjustment inaccuracy of meters measuring large
on any element affects only that blocks of power or used for billing
element, whereas the full-load adjust purposes, it is essential that an "as
ment on any element affects all found" test be made, and that nothing be
elements. In fact, in some meters not all disturbed before making this test. Also,
of the magnets are adjustable. Thus, it the information gathered in this test will
will be seen that unless the same be valuable in locating the source of any
percent error exists at both loads, it is inaccuracy found. The following
usually better to make the light-load procedure is recommended:
adjustment first.
37 (FIST 3-10 1/92)
(1) Examine all wiring, seals, and maintenance required, the following test
other external conditions without runs should be made regardless of
disturbing anything. Record any un whether or not the "as found" test was
usual conditions found and satisfactory. If results of this test are
anything that might affect meter within the limits specified in Paragraph
performance. Also, record the 6.1, record in the "as left" section of
meter reading and time of removing Form 105. Otherwise, make adjustments
from service. and repeat runs as described below until
specified accuracy is obtained. Note any
(2) Make connections for testing repairs and adjustments made in the
without disturbing anything that can appropriate spaces on Form 105.
be avoided.
10.5.1. Overall test. - With all po
(3) With potential coils excited and tential coils connected in parallel and
no current in the current coils, note current coils in series, make the fol
whether meter creeps. Record. lowing runs:
(4) With all potential coils excited, (1) 100-percent current, 100-per-
make following tests to obtain data cent power factor
on overall performance and perfor
mance of each element separately. (2) 50-percent current, 100-per-
Record results on Form 105 (Figure cent power factor
23).
(3) 10-percent current, 100-per-
cent power factor
Three runs should be made at each of If no appreciable changes from the
the above test points and the results last test are found, proceed to in
averaged. The 50-percent lagging power spect, clean, and make "as left"
factor and the separate element tests check. Otherwise, do not make any
can be omitted if the "as found" condition adjustments at this point but proceed.
shows no appreciable change from
proceeding tests. 10.5.2. Individual element test.
Required for laboratory calibration of
10.5. CALIBRATION TEST. Information meters, or if meter proves faulty.
obtained in the "as found" test should be Same as (1), (2), and (3) above with
analyzed and used as a guide to assist all potential coils excited, but taking
in locating any existing trouble during the one element at a time with no current
cleaning and inspection of the meter in the other elements. This test
which precedes a Calibration test. Refer should be made even if the overall
to Paragraphs 9.2, 9.3, and 9.4,
regarding cleaning and inspection. After
cleaning and performing any other
(FIST 3-10 1/92) 38
test was satisfactory because the test, it will not be difficult to decide
individual elements may have errors which element and which
that compensate in an overall test. If adjustment should be changed to
errors are found in any element on achieve proper balance at all
individual test, adjustments should be loads and at 50-percent power factor.
made as discussed in previous The accuracy of any individual
paragraphs and runs repeated until element should, of course, be
each element has been adjusted maintained within the prescribed
within prescribed limits, then proceed. limits.
10.5.3. Balance check. 10.5.4. Final overall test. - Following
Required for laboratory calibration the individual element test and
of meters, or if meter proves bucking check, an overall test run
faulty. (Not applicable to single- should be made as in Paragraph
phase meters.) The individual 10.5.1. if the results are satisfactory
element test should have (within the limits prescribed in Para
established good quality of ele graph 6.1), record the data for each
ments; however, this simple element and overall on Power O&M
balance check is recommended Form 105 (Figure 23) in the "as left"
to assure that the elements are section. If the overall test does not fall
closely matched. Take two within prescribed accuracy limits, it will
elements at a time and oppose or be necessary to go back, readjust the
"buck" them while varying the individual elements, and repeat the
load current from 10 to 100 balance check and overall test. In
percent, and also at 100-percent readjusting the individual elements to
current, 50-percent power factor. adjust overall registration, all elements
The "bucking" condition is should be changed by equal amounts
obtained by reversing the current unless it is known from previous runs
connections of either element. that some elements can stand a
The disk should stand still; or greater change in the required
rotate very slowly in one direction, direction than others.
stop, and reverse, as the load is
varied from 10 to 100-percent. If 10.6. CONCLUDING THE TEST. After all
the rotation is always in the same adjustments have been made, the final
direction and exceeds 1 rpm, calibration data recorded, and the meter is
readjustment of individual ready to be placed back in service, there
elements is indicated. However, are still several points to be covered:
proceed with the bucking test at
50-percent power factor first to 10.6.1. Resetting register. - To
determine whether the inequality compensate for the registration lost
is due to light-load or power-factor while the meter was out of service, it
(lag) adjustment. From an may be desirable to reset the meter
analysis of the behavior on this dial to an appropriate reading corn
test and the percent registration
records of the individual element
39 (FIST 3-10 1/92)
puted from the length of time and and customer representatives and
average load shown by indicating that a signed copy is furnished for
meters during the meter outage. Or, the customer's files, if a billing
the dial may be left as is and the meter.
station operator given the necessary
data for making adjustments in station 10.6.6. Cleanup. Replace any
records. This would include the equipment or furniture moved for
reading at the beginning of the out the test, and clean up the area if
age, times of beginning and end of necessary.
outage, and reading when placed
back in service. The register is not to 10.6.7. Customer relations. Every
be removed after the final test to effort should be made to maintain and
adjust for unmetered energy. enhance good relations with the
customer, not only by courtesy, but by
10.6.2. Removal of test equipment. a thorough and efficient test procedure
After reconnecting the meter and in which the representative is offered
removing all jumpers, replacing fuses, an opportunity to participate.
etc., recheck all work carefully to see
that all connections and equipment 10.7. METER TEST RECORDS. As
have been restored to proper mentioned in the paragraphs on testing,
conditions. Be especially careful not to Bureau Power O&M Form 105, "Watt-hour
leave any test jumpers connected, or and Demand Meter Test Report," Figure
test switches in wrong positions. 23, or other revision thereof, is used to
record "as found" and "as left" test results.
10.6.3. Check potential. - Check that In addition, there is provision for entering
potential is present on all elements by meter data, servicing performed, adjust
using a voltmeter, or by disconnecting ments made, etc., as will be seen on the
potential leads at meter studs. If the sample copy of the form (Figure 23). It is
meter is equipped with small potential important that all pertinent information
indicating lamps, check that all are regarding the test be entered on the form.
operating. In the case of meters used for billing
purposes, the original signed copy should
10.6.4. Meter seal. - Seal the meter in be preserved in a permanent file for at least
the presence of the customer's as long as the duration of the contract for
representative, if a billing meter. sale of power. Meter maintenance and test
records should be included in the
10.6.5. Test records. - Make maintenance card file so that tests will be
sure test records are complete scheduled at regular intervals not greater
and signed by both the Bureau than 1 year.
(FIST 3-10 1/92) 40
Figure 23
41 (FIST 3-10 1/92)
Xl. DEMAND AND TOTALIZING watt-hour meter and a strip-chart on
METERS which a pen draws a line during each
demand interval. The length of this
11.1. INDICATING DEMAND line shows the maximum demand.
METER. The indicating type of Thus, there is a complete record of
demand meter is commonly used by demand versus time. Briefly, the
utilities and consists of an attachment functioning of this type of meter is as
to the customer's watt-hour meter follows: A pen-driving gear train
which indicates the maximum mechanism geared to the watt-hour
demand that has occurred since the meter disk shaft moves the pen
last reading of the meter when the across the chart for 30 minutes, in the
demand indicator was reset to zero. case of a 30-minute demand interval.
There is no indication of when the At the end of this time, a Telechron
maximum demand occurred. The motor or clock device returns the pen
most common type consists of a to zero and advances the chart
pointer that is held by friction at the approximately 1/16 inch for the next
highest point to which it has been line to be drawn. A quirk or "pot hook"
pushed by a mechanism geared to at the end of the inked line is
the watt-hour meter disk shaft during produced just before the pen returns
the demand interval. A small to zero to facilitate reading the
synchronous (Telechron) motor maximum. A record of both 15- and
resets the actuating mechanism to 30-minute demand may be obtained
zero at the end of each demand in this meter by arranging to advance
interval. Demand intervals are the chart at the end of 15 minutes,
normally 30 or 15 minutes, and which produces a step in the inked
maximum demand may be defined line.
as the maximum integrated (average)
demand in kilowatts for the specified Maintenance and servicing of the
demand interval. demand part of the meter is purely
mechanical and should only be at
11.2. RECORDING DEMAND ME- tempted after familiarization with the
TERS. Demand meters as used in manufacturer's instructions. The watt-
Bureau plants usually record the hour element is identical to meters
maximum demand on a chart or tape. without the demand feature and is
Brief descriptions of some of the tested and serviced in the same
most common types follow: manner, making sure that during
calibration the demand device is op
11.2.1. Strip-chart recorders. - erated so that the additional load
The General Electric Type DG and imposed by it is taken into account.
Westinghouse Type R recording de
mand meters are quite similar and The most common trouble with this
are probably the most frequently en type of meter is improper inking. The
countered in Bureau installations. inking system must be kept clean, and
They consist of a 2- or 3-element only the proper type of ink used.
(FIST 3-10 1/92) 42
If the pen does not return to zero properly Equipment suggested for the test is a
or pick up ink on the return; if the pen 120-volt variac, an analyzer or voltmeter,
mechanism gets "out of time" or trips at a fused test cord with jacks for the
the wrong time; if the chart does not analyzer or voltmeter and plugs attached
advance correctly; or any other with solder for the G.E. Clock, M-30
malfunction develops, the manufacturer's demand clock, and Westinghouse Clock.
instructions should be consulted before
making adjust-merits. Some early types of 11.2.2. Impulse-type demand meter.
recording demand meters are now Another type of demand meter is a
obsolete and are continuing sources of recorder operated by impulses received
trouble. In such instances, it is from a contact device installed in one or
recommended that they be replaced by a more watt-hour meters. This recorder
modern type of better design. totalizes the received impulses during the
demand interval and makes a record on a
Recording and indicating demand watt- chart or tape. The General Electric Type
hour meters with pen drive systems G records maximum demands as a series
sometimes have difficulties related to the of inked lines on a continuously rotating
drive system. When a malfunction occurs, circular chart, whereas the General
the pen will fail to give readings or give Electric Type BR and Westinghouse WA
excessive readings depending on the part use a strip chart and inking system like
that fails. Improper readings cause extra the Type DG and Type R, respectively.
trips on the part of maintenance per The General Electric Type PD prints
sonnel. A test which can be performed at numerals on a paper tape at the end of
the time the meter is tested can each demand interval. These types also
apparently predict failures. One of the have a counter or register that records the
principal parts of the pen drive system is total number of impulses received. Thus,
the interval clock. To make the test, a there is a record also of kilowatt-hours,
variable voltage is applied to the motor; which in the case of several connected
the voltage is raised from the zero point meters serves to totalize kilowatt-hours.
until the motor starts and then it is
lowered until it stops. Motors in the best Modern impulse-type demand recorders
condition have the largest start-stop register the demand on magnetic tape or
interval. Some experimentation may be punched paper tape which eliminates the
required to determine the proper interval need for visual chart scanning by
for a given watt-hour meter. Past results providing data in a form suitable for
show that an interval of less than 35 volts the utilization of automatic data-handling
indicates a faulty motor for General
Electric VM3-A or VM4-A meters.
43 (FIST 3-10 1/92)
techniques. The tape is a recording same voltage is to use a single watt-hour
medium for interval time pulses and meter whose current coils are connected
kilowatt-hour or kilovar-hour pulses. The to paralleled secondaries of current
demand information is translated transformers in the circuits to be totalized.
automatically into digital form on punched The current transformers must all be the
cards or paper tape for direct entry into same ratio, or auxiliary current
billing computers. Examples of this transformers must be introduced into the
equipment are the Westinghouse Types secondary circuits to achieve identical
WR-2 and WR-4 demand recorders, the ratios.
Duncan Types BTR-2W and 4W, the
General Electric PDM recorder and PDT Still another method of totalizing is to use
translator making up the Pulscript a meter with 4, 6, 8, 9, 12, etc., elements,
Demand Recording System, and the the addition being performed by adding
Sangamo Type DPR, punched paper the torques produced by elements in the
tape recorder. various circuits by means of a common
shaft or two coupled shafts. The contact
11.2.3. Totalizing demand meter. - As device should be a break-before-make
mentioned above, energy measurements type providing a form "C" pulse and the
from several watt-hour meters may be contacts should be mercury-wetted (to
totalized on a registar that is actuated by eliminate contact bounce) in order to
impulses received from contact devices provide for maximum accuracy. A
installed in the individual watt-hour minimum time of 0.8 second is necessary
meters. The meter constants, if different, between outgoing pulses from the
must be taken into account by proper totalizer to the recorder. This permits
choice of contact device gear ratio and sufficient space between the pulses
number of points on the cam which recorded on magnetic tape for translation
operates the contacts. Another method of purposes.
totalizing energy in several circuits of the
(FIST 3-10 1/92) 44
REFERENCES
1. Instruction sheets issued by the man- 3. Electric Power Metering, by A. E.
ufacturer for a specific meter should have Knowlton, is an excellent book on all
been furnished with the equipment and phases of metering theory and practice.
are the best guide to use in servicing.
4. The Code for Electricity Metering, ANSI
2. The Edison Electric Institute, 750 Third Standards, C12-1965, is the accepted
Avenue, New York, New York 10017, has standard prescribing construction details,
published the Electrical Metermen's acceptance test procedures, accuracy
Handbook, which is a compilation of data requirements, and service tests of meters
on different manufacturers' meters, and and associated auxiliary equipment.
also contains general information on
testing and test equipment.
45 (FIST 3-10 1/92)
APPENDIX A
SUGGESTED GUIDELINES FOR MAINTAINING REVENUE
METERING EQUIPMENT
A-1. TYPES OF METER TESTS.
Time
a. Routine Field. - Meters are tested and Type of load between tests
adjusted by the series- parallel method
using the procedure outlined herein. The Preference customers
only correction factor used is that of the 100,000 kW and above 6 months
rotating standard. Test points are 10, 20, Below 100,00 kW 12 months
50, and 100-percent amps, 1.0 power
factor and 100-percent test amps, 50 Project loads
percent lagging power factor.
100,000 kW and above 6 months
100 kW to 100,000 kW 12 months
b. Precise Field. - Meters are tested as Below 100 kW, 3 phase 24 months
in routine field tests except their Single phase, residential 60 months
adjustment includes correction for in In addition, all new equipment scheduled for
strument transformer and test equipment installation should be laboratory tested and
errors. operated for 7 days on test, time permitting,
prior to being placed in service.
c. Laboratory. - The meter is tested in
the laboratory. Tests include individual A-3. ROTATING STANDARDS.
element as well as all elements
combined. Tests are at 10, 20, 50, and a. Minimum Required. - Each office
100-percent test amps, 1.0 power factor engaged in the testing and maintenance
and 100 percent test amps, 50-percent of revenue metering equipment should
power factor. After the tests and maintain a minimum of three rotating
adjustments are completed, the meter is standards; one reference and two (or
operated for 7 days if possible before more) field standards. The reference
returning to regular service. standard, chosen for stability and
reliability, should be maintained in the
Instructions for reading meters should be meter shop and not used for routine field
issued by the appropriate regional or testing. Field standards should be used
project office. to calibrate revenue meters in the field
and should be compared with the
A-2. FREQUENCY OF METER TESTS. reference standard before, after, and at
The intent of this paragraph is to insure least once every 2 weeks during meter
proper testing and maintenance on the testing to assure that the field standard
more important metering installations. has not been damaged when
Therefore, in line with utility practices, transporting between locations. If this
meter tests should be on the following comparison shows a change of more
schedule:
47 (FIST 3-10 1/92)
than 0.15 percent from previous change in temperature, the voltage
comparisons of the two standards, meter of the standard cell changes by
tests should be suspended until the approximately 10 microvolts.
difference is resolved. All rotating
standards should be calibrated at least (d) Humidity. - The ideal humidity
once every 12 months. range is 40 to 55 percent. Exces
sive humidity should be avoided.
b. Calibration. - Detailed require-merits
for improved accuracy in the calibration of (e) Power supplies. - Both the d-c
rotating standards are provided in "Code and a-c power supplies should be
for Electricity Metering." 5th Edition or closely regulated. The d-c supply
later, ANSI Standards C12 published by shall be free from ripple. The a-c
the American National Standards Institute supply shall be substantially free
(formerly the United States of America from waveform distortion with the
Standards Institute formerly the American RMS waveform distortion not ex
Standards Association). These calibration ceeding one percent of the mag
requirements should be adhered to. The nitude of the fundamental. The
following paragraphs modify them as phase relationship of the combined
necessary to meet the needs in the current and voltage supplies shall be
Bureau of Reclamation. adjustable.
(1) Laboratory Conditions. (2) Laboratory Equipment.
(a) Laboratory restrictions. - The (a) Accuracy classification. - All
laboratory should be restricted to equipment used in the calibration of
personnel engaged in meter cali rotating standards shall be of the
bration work. highest accuracy classification
obtainable, preferably 0.1 or 0.25.
(b) Contamination or other inter
ferences. - The laboratory shall be (b) Maintenance. - All equipment
free of atmospheric contamination, should be maintained in the labo
mechanical disturbances or ratory, handled as little as possi-hie,
noises, and electrical or magnetic and not used for routine mea
interferences in order that the re surements at locations outside the
sults of the calibration work will not laboratory.
be adversely affected.
(c) Reference standard. - A rotating
(c) Temperature. - The temperature standard, chosen for stability, should be
should be maintained at ap maintained in the laboratory as a
proximately 23O C, the temperature at reference standard. This should be used
which the standard cells are for the checking of rotating standards
calibrated by the National Bureau of
Standards. Note: For each 4O C
(FIST 3-10 1/92) 48
when regular calibration tests are not of ANSI Standards C12, paragraph 4.5.6
scheduled. "DC Ratio Devices."
(d) Standard cells. - A minimum of three (g) AC ratio devices. - AC ratio
unsaturated cadmium cells should be devices should meet or exceed the
maintained: one (chosen for stability) requirements of ANSI Standards
should be designated as the working cell; C12, paragraph 4.5.7 "AC Ratio
the others as reference cells. The working Devices."
cell should be retained in the laboratory,
maintained at 23O C ± 2 O C, and disturbed (h) AC-DC transfer standards. -AC
as little as possible. It should not be DC transfer standards should meet
shipped for NBS certification. The o r
reference cells should be used to exceed the requirements of ANSI
calibrate the working cell. Standards C12, paragraph 4.5.8
"AC-DC Transfer Standards."
The voltages of the reference cells should
be compared with that of the working cell (i) Time interval. - The standard time
immediately before shipping for interval used should be traceable to
certification purposes and upon return NBS.
after first checking that their voltages
have stabilized. The voltage of the (3) Periodic Verification of Reference
working cell is to be determined by Standards. Laboratory equipment should
comparison to those of the certified be checked by NBS (or other competent
reference cells. Each curve should show laboratory having NBS traceability) in
a uniform negative slope which accordance with the following schedule:
represents a decrease in voltage with
time. Any radical change in the curve will (a) Standard cells.
be cause for replacing the cell. Any cell
whose voltage is found to be unstable (aa) Working cell. - Only when
should be replaced. purchased or used as reference
cell prior to being assigned as
(e) Standard resistors. -Sufficient working cell.
standard resistors should be maintained
in order that the complete range of tests (bb) Reference cells. - At least
necessary for the calibration of rotating once each year.
standards can be accurately performed.
(b) Standard resistors. - Every 2
(f) DC ratio devices. - DC ratio devices years.
should meet or exceed the requirements
49 (FIST 3-10 1/92)
(c) Standards for ratio and for calibrated by using several com
transfer (a-c or d-c). These should binations of precisely measured d-c
be verified by NBS or an volts and currents. The rotating
independent laboratory whenever standards are then compared to
their self-checking features fail to the wattmeter.
respond or whenever there is rea
son to question their performance. The procedure is slow, requires the skill
of three or four technicians, and being
(4) Indicating Instruments. - Alternating replaced by the new electronic method
current ammeters, voltmeters, watt (see paragraph (b)). However, since the
meters of appropriate ranges and of high direct comparison method will be used for
quality are required as laboratory working some short period of time, it is described
standards. in detail.
(a) Accuracy class. - Indicating (aa) Calibration of standard
instruments should have an ANSI wattmeter. - The standard watt
accuracy class of 0.1 or 0.25. meter is calibrated by using pre
cisely measured values of d-c
(b) Stability. The instrument should currents and voltages. The currents
be capable of being read within 5 are 1.5, 2.5., and 5.0 amperes,
seconds after a step change is while the voltage ranges selected
made. vary between 100 and 125 to
correspond with those experienced
(c) Repeatability. The instrument at the various revenue metering
must demonstrate repeatability for installations.
several successive readings of
identical measurements. The test requires the services of
four technicians: one to maintain
(d) Intemal heating. - Instruments precise voltage; one to maintain
should be energized only during precise current; one to accurately
testing in order to avoid changes in read the standard wattmeter, and
accuracy because of internal one to record data. The test circuit
heating. is shown in Figure A-1. Using an
exact value of current and voltage,
(5) Calibration Procedures. - Two five readings (with changes be
different, independent procedures for the tween each) are made on the
calibrating rotating standards are wattmeter. The polarity of the circuit
possible. is then reversed and five additional
readings are taken for the same
(a) Direct comparison. The current and voltage values. The
standard wattmeter is accurately average of the ten readings divided
(FIST 3-10 1/92) 50
voltages. These are then used to
calibrate the rotating standards.
(bb) Calibration of rotating
standard. - The test circuit is
shown in Figure A-2, and the
rotating standard is to be cali
brated for 0.5, 2.5, and 5 am
peres at unity power factor and 5
amperes at 50-percent lagging
power factor for the range of
voltages encountered in revenue
meter testing.
A series of five readings of the
ammeter, voltmeter, standard
wattmeter, rotating standard, and
timer for each value of voltage,
current, and power factor are
required. Each measurement
takes three minutes in order to
secure better readings on the
rotating standard. From these
measurements, the following
calculations are made in order to
Figure A-1. Calibration of standard wattmeter circuit determine the correction factors
diagram, direct comparison method. for the rotating standard:
by the true watts (precise current For 5 amp. range on rotating stan
times precise voltage) gives the cor dard:
rection factor for that combination of
voltage and current. Similar tests and Calculated revs.
calculations are made for other
current and voltage combinations, true watts x time in secs
thus providing calibration curves for =
the standard wattmeter for several 2,160
51 (FIST 3-10 1/92)
calc. revs.
C. F. =
actual revs.
Where,
true watts = true watts as determined
from the calibrated watt
meter.
time in secs = reading of the timer.
actual revs. = reading of rotating
standard.
When readings are taken at the
50-percent lag power factor, an
additional correction must be
made to the true watts. This
correction is due to the difference
between ac-dc reading of the
wattmeter. The corrections for this
wattmeter are minus watts, and
this is determined by multiplying
the reading on the wattmeter by
the percent difference from the
NBS certificate. The minus watts
are then subtracted from the true
watts to give actual true watts for
the 50-percent lag power factor.
(b) Electronic or digital method.
(aa) Procedure involved. - The
Figure A-2. Calibration of rotating standards.
block diagram, Figure A-3, shows
the basic schematic for this
or, for the I amp range, method. The electronic wattmeter
produces a d-c voltage output
Calculated revs. which is proportional to the input
power. Adjustment is such that
true watts x time in secs 600 watts input equals 1 volt d-c
= output. This output voltage is fed
432
into a high accuracy frequency
converter which converts the 1
volt d-c to 10,000 hertz. Thus:
From which the correction factor,
C.F. is calculated.
(FIST 3-10 1/92) 52
Since the lB-10 has a Kh = 0.6, one
revolution equals 36,000 counts.
The count for other values of
amperes, volts and power factor
would be proportional to the watt-
seconds involved.
(bb) Calibration of the test equipment.
The watt-hour calibrator is tested as a
unit. Accurately measured values of dc
voltage and current are fed into the
watt converter (115v, 5 amp., for 600
watts).
The output of the watt converter is fed
into the voltage-to-frequency converter
whose output is fed into the preset
counter operating in the frequency
counter mode. The average of the
forward and reverse readings is
determined. Then, average watt X
1000 over 600 equals the desired
count.
Formula:
average watts x 1000
Figure A-3. Calibration of rotating standard, Desired count =
electronic method. 600
Correction Factor = C. F.
5 amps, 115 volts per second Desired Count
= 600 watt-seconds =
= 10,000 counts Average Count
or
This correction factor must be
600 combined with any other correction
600 watt seconds =
factors involved in the equipment
600
3,
such as CT correction factor,
correction factors for the d-c
= 1/6 watt-hours = 10,000 counts potentiometer, etc.,
or
1 watt-hour = 60,000 counts.
53 (FIST 3-10 1/92)
to arrive at the over-all correction b. Final Clearance. Immediately prior to
factor for the watt-hour calibration removing the revenue metering
standard. equipment for tests, obtain final clearance
from the Power System Dispatcher.
The preset counter has sufficient Record data required.
capacity to permit a check of 600
watts being measured for 3 c. "As Found" Tests. - Connect the test
minutes (1800 watt-minutes). equipment for single-phase testing and
make "as found" tests described below.
The demand recorder is to be retained in
(cc) Calibration of rotating service throughout the tests unless repairs
standards. - The preset will be set are necessary. Its indicating register
on the counter, thus allowing the should be reset to its original "as found"
rotating standard to operate for a reading upon completion of the tests. Do
given number of watt-seconds, for not remove meter covers or disturb the
a predetermined voltage and meters prior to the "as found" tests,
current, the counter representing Record all necessary metering data just
the true value of watt-seconds. prior to removing the metering equipment
The correction factor for the from service.
rotating standard is determined by
comparing the reading on the (1) Performance. Perform "as found"
standard to the true watts which it tests for the meters connected:
should have read.
(a) Potential elements in
(6) Calibration Reports. - Each field parallel; current elements in
office should maintain a complete series.
file on the calibration of its stan
dards. One copy of the calibration (b) Single phase, single
report should be included with the element (when required).
report of revenue meter tests when
ever tests are made at the major (2) Tests to Be Performed. - Test
interconnections only. each condition for 0.5, 2.5, and 5.0
amps, unity power factor and 5.0
amps, 50-percent lagging power
A. PRECISE METER TESTS factor at normal metering voltage.
The average of three tests for each
A-4. TEST PROCEDURE. current value shall be considered
the "as found" correction factor.
a. Warmup. - Warm up to the stan
dard for at least 1 hour immediately d. "As Left" Tests. - Clean, perform
prior to meter tests. maintenance, and adjust the meters as
necessary. Make "as left" tets for the same
test currents listed in Paragraph c(2)
(FIST 3-10 1/92) 54
above. The maximum permissible errors (c) Light load (0.5 amp)
allowable are given in Paragraph e below. unity power factor 99.3 to 100.7
(d) Full load (5 amps) 50%
e. Permissible Error. - The following lagging power factor 99.3 to 100.7
limits are to be observed when calibrating
metering equipment: (e) Stator balance, full
load (agreement
between individual
(1) With the potential coils connected elements) 99.3 to 100.7
in parallel and energized at average
metering voltage, and the current coils
in series:
A customer should be permitted to install
Percent his standard in the test circuit for
registration comparison purposes only if he provides
satisfactory evidence that his standard has
(a) Full load (5 amps)
unity power factor 99.7 to 100.3 been properly calibrated within the past 12
1 amp unit power 99.7 to 100.3 months. If this comparison shows an
factor average deviation of more than 0.2-percent
between the customer's standard and that
(b) Half load (2.5 amps) of Reclamation, further meter testing will be
unity power factor 99.7 to 100.3
suspended until the difference has been
(c) Light load (0.5 amp) resolved. If any standard in a group of
unity power factor 99.7 to 100.3 standards shows a deviation of more than
0.2-percent from the average, or if it
(d) Full load (5 amps) 50% appears that it is inaccurate, that standard
lagging power factor 99.3 to 100.7
should be removed from the test and not be
(2) Individual elements, tested at used in any tests.
average metering voltage: Usually
laboratory tests or after major overhaul, For information on adjustment of General
not required if "as found" test shows no Electric watt-hour meters, see Bulletin No.
significant change. GET-813G "How to Test and Adjust
General Electric A-C Watt-hour Meters."
Percent
registration f. Comparison of Data. - If possible,
compare the kwh recorded on the watt-hour
(a) Full load (5 amps) 99.7 to 100.3 meter during the tests with that recorded on
unity power factor
the demand meter and/or totalizer
(b) Half load (2.5 amps) cyclometers. Account for any difference.
unity power factor 99.7 to 100.3 Record all data.
55 (FIST 3-10 1/92)
A-5. CONCLUSION OF TEST. - Upon nearest one-ten thousandth
completion of the test: (0.0001) at unity power factor.
(1) Check all meter connections, (3) Computations to compensate
being sure that all voltage and for the effect of the combined
currents from the instrument instrument transformer correction
transformer are restored to the factors on the meter under test
meters. Make stopwatch check of should be carried to the nearest
meter as final proof of proper one-ten thousandth (0.0001 ).
operation.
(4) The correction factor of the
(2) Replace all seals. standard watt-hour meter should
be to the nearest one-ten
(3) List all test personnel and thousandth (0.0001).
witnesses and have at least one
representative from each party (5) The metering correction factor
sign the test data. should be recorded to the nearest
one-ten thousandth (0.0001).
(4) Immediately report all data
taken in Paragraphs A-4 d and f. (6) The results of the tests should
be plotted on the graph paper
(5) Mail three copies of the original using the following standard
handwritten test report to the coordinates:
appropriate office.
abscissa: 1 inch = 1.0 amperes
B. SUPPLEMENTAL INFORMATION ordinate: 1 inch = 0.01 =
correction factor
A-6. METERING CORRECTION FAC
TOR. - In computing the factor to be used These are to be included with the
to correct for instrument transformer error, test report.
the following procedure should be
adhered to: A-7. METERING VOLTAGE. - The me
tering voltage to be considered when cal
(1) The agreed upon transformer ibrating the rotating standards should be
ratio correction factors and the the average bus voltage which exists
phase-angle correction factors for during normal Icad conditions referred to
each of the CTs and PTs will be secondary side of the potential trans
used. These should be determined formers used for metering.
to the nearest one-ten thousandth
(0.0001) for the ratio and one- A-8. DATA. - All pertinent data are to be
tenth of one degree (0.1o) for the recorded immediately prior to removing
phase-angle. the equipment from service for testing
and immediately after restoring equip
(2) The net transformer correction ment to service.
factor should be computed to the
(FIST 3-10 1/92) 56
C. ROUTINE METER TESTS
The customer should be permitted to in
stall his standard in the test circuit during
A-9. INTRODUCTION. - This procedure warmup time for comparison purposes.
applies to the testing of revenue meters No credence will be given to the equip
at preference agencies and project loads ment unless evidence is produced to
but excludes major power interchanges. show that the standard has been recently
Unless otherwise instructed, instrument calibrated for use at the currents and
transformer correction factors need not voltage involved; also, that satisfactory
be incorporated into the test adjustments. care is taken in handling and transporting
of the standard.
Routine tests are to be performed in ac
cordance with the schedule set up in A-11. TEST PROCEDURE.
Paragraph A-2 of this appendix and
whenever repairs are made to the watt- a. Instrument Connections. - Con
hour meter. Special tests should be made nect the test instruments to perform
whenever requested by the customer, or single-phase tests. Where feasible,
if the operation of the meters becomes the demand recorder should remain in
questionable. operation during the tests and will re
cord test energy.
Laboratory tests are to be made before
placing new meters in service. The watt- b. Warmup. - Warm up the standard
hour and var-hour meters should be for at least 30 minutes immediately
tested by individual element, as well as by prior to the tests.
all elements combined with the single-
phase series-parallel method. The de c. Equipment Removal From Ser-
mand meter should also be laboratory vice. - Record the exact time and the
tested and adjusted. All equipment should data specified in a test report at the
be operated in the laboratory for 7 days time the revenue metering equipment
on phantom Icad before placing in is removed from service for testing.
service, time permitting. Watt-hour meter register readings are
to be estimated to the nearest 0.1. DO
A-10. PRELIMINARY. - Approximately 10 NOT advance a magnetic tape to
days prior to the test, notify the customer identify the test period. This would
so that arrangements may be made to result in the balance of the tape being
witness these tests, if they so desire. out of proper timing.
Immediately before the regular annual d. "As Found" Tests. - With the cur
meter tests, the portable rotating standard rent elements in series and the
used should be calibrated in the potential elements in parallel, make
laboratory and final correction factors or "as found" meter test, being sure the
curves established. The procedure for meter is not disturbed in any before
calibrating rotating standards and equip the test. Determine the average
ment is covered in Paragraph A-3 of this correction factor for three runs at each
appendix. of the following test points: 0.5, 2.5,
and 5.0 amperes, unity power factor.
57 (FIST 3-10 1/92)
Similar tests shall be made for each Percent
element when required (see registration
Paragraph A-1, Types of Meter
Tests). The calibration curve used (a) Full load (5 amps)
with the standard shall be that unity power factor
1 amp unity power
obtained for a voltage with ± 2-1/2
factor 99.7 to 100.3
percent of the metering voltage exist
ing at the time of the test.
(b) Half load (2.5 amps)
e. Maintenance. - Clean and perform unity power factor 99.7 to 100.3
any other maintenance work on the
meter that may be found necessary. (c) Light load (0.5 amp)
Give brief description of work per unity power factor 99.7 to 100.3
formed in the test report.
(d) Full load (5 amps) 50%
f. Indicating Demand Register. lagging power factor 99.3 to 100.7
The indicating demand register, if so
equipped, should be checked by (2) Individual elements (when required), tested
using a register self-checker and the at average metering voltage:
procedure outlined in Chapter 16,
Electrical Metermen's Handbook, Percent
Seventh Edition. The results of these registration
tests shall be reported under
"Remarks" on the regular test form. (a) Full load (5 amps)
unity power factor
1 amp unity power
g. "As Left" Tests. - Make "as left"
factor 99.7 to 100.3
tests at the same test points as listed
for the "as found" tests (Paragraph Al
I d above) and adjust, if required, (b) Half load (2.5 amps)
until the correction factors for all test unity power factor 99.7 to 100.3
points are within the limits specified
in Paragraph A-11 h. (c) Light load (0.5 amp) 99.7 to 100.3
(d) Full load (5 amps) 50%
h. Permissible Error. - The following
lagging power factor 99.3 to 100.7
limits are to be observed when
calibrating metering equipment.
(e) Stator balance, full
load (agreement
(1) With the potential coils con
between individual
nected in parallel and energized
elements) 99.3 to 100.7
at average metering voltage,
and the current coils in series:
Note: Individual element and 50% power factor
tests are not normally required - only when
rebuilding the meter or making tests in the
laboratory.
(FIST 3-10 1/92) 58
For information on adjustment of General (3) List all test personnel and
Electric watt-hour meters, see Bulletin No. witnesses and have at least one
GET-813G "How to Test and Adjust representative from each party
General Electric A-C Watt-hour Meters." sign the test data.
i. Equipment Return to Service. (4) Report all data taken in
Record the exact time and readings at the Paragraphs A-11 c and i to the
time the metering is restored to service. designated supervisor for use in
Compare the kWh recorded on the watt- making adjustments in demand and
hour meter(s) during the test with: energy.
(1) That calculated from the D. PERIODIC OR MIDMONTH INSPEC-
stampings on the printed TIONS
demand tape and the
associated cyclometer readings; A-13. REQUIREMENT. - Periodic or
or "midmonth" inspections should be made at
times other than regular meter reading
(2) That calculated from the de- dates to inspect, repair, and maintain the
mand register readings if equipment. All adjustments and/or repairs
magnetic-type tape. should be reported. These inspections shall
be scheduled approximately midway
If a totalizer is installed, its between meter reading dates.
cyclometer readings should also
be checked against the watt-hour a. Inspection Schedules. - Period or
meter registrations. The reason for "midmonth" inspections shall be
any discrepancy should be scheduled as shown below for installa
included in the test report tions having:
whenever possible.
(1) Printing demand meters
A-12. CONCLUSION OF TEST.
(a) Pumping plants not operated
(1) Check all meter connections, during off season. - Inspect im
being sure that all voltage and mediately before start of pump
current conductors from the season and at end of season
instrument transformers are
connected to the metering (b) Project loads less than 100
equipment. Make stopwatch check kW- every sixth month
of meter and check potential lights
to assure that the meter is (c) Loads to 50 MW - every third
operating properly. DO NOT reset month
the watt-hour meter register to
compensate for estimated (d) Loads over 50 MW - monthly
unmetered energy. or oftener, as required
(2) Replace all seals.
59 (FIST 3-10 1/92)
(2) Indicating demand registers (3) The tape for distinct, legible,
properly positioned printings.- Dirty
(a) Newly installed - monthly until print wheels and/or dried, used carbon
reliable operation is attained tapes, or improperly installed tapes
may be found. The proper tape is
(b) Thereafter - semiannually General Electric Company Catalog
No. 4210493P1, color: black. DO NOT
(3) Magnetic tape recorders substitute as high temperatures may
dry out less expensive tapes.
(a) Newly installed - monthly for
first 3 months, or until such time as (4) The record gage for ample tape.
reliable operation has been at - Proper tapes are:
tained
PD-5 through 8: General Electric
(b) Thereafter- semiannually or at Company Catalog
No. 1796688G17
time of meter inspection or test
PD-55F and 57F: General Electric
(4) Single-phase service - annually Company Catalog
No. 9889524G16
b. Inspection of Metering Equipment.
Since different types of recorders are All are 24-hour tapes for 30-minute
used at various locations, inspection demand intervals.
procedures will vary. Check the following
and repair as indicated: c. Magnetic Tape Recorders. - With the
recorder in service (DO NOT open
(1) The demand counter. - Check its "change tape" switch), check the following
registration with that on the watt-hour and repair as indicated:
meter since last inspection. If not in
agreement, either the counter or the (1) The timing on the register. - If off
contact device in the watt-hour meter by more than 3 minutes, advance to
could be faulty. proper time by turning the capstan
tape drive. DO NOT turn the hour
(2) The timing on the demand meter. pointer by hand to the proper time use
If in error by more than 3 minutes, the capstan tape drive for this
correct and mark the tape accordingly. purpose. This is necessary to provide
DO NOT obliterate any present or the correct number of demand
future printings. If magnetic-type, intervals when translating the tape.
advance the tape by means of the Record time and date on meter
capstan. Do not adjust the clock reading card.
except at start of demand period.
(FIST 3-10 1/92) 60
(2) The tape for proper (4) Watt-hour meter register
operation. The supply and readings, difference and kwh.
take-up reels should have
approximately the same (5) Counter readings, difference
amount of tape at midmonth. and kwh.
(3) Demand and time pulses. (6) Maximum demand dial reading.
Use high impedance
earphones to determine if each (7) The difference between the kwh
are being transmitted to the calculated under (4) and (5) above.
tape.
If the operation of the contact device and
(4) Registration on demand demand meter has been correct, these
counter ('dials). - This should should agree within the watt-hour meter
be equal to that on the watt- multiplier.
hour meter register for the
inspection period involved. (8) The time in seconds for two revo-
lutions of the disk of the watt-hour meter
(5) For dirt, insects, or other and the var-hour meter. Show N.L. when
foreign materials. the load is zero. These are required to
compute instantaneous power factor and
d. Watt-hour-demand Meters. - to check the recorded demand.
Check for and repair as necessary.
(9) The metering potential voltage.
(1) Dirt, insects, or other (Essential in recommending the appli
foreign materials. cation of capacitors.)
(2) That the indicating demand (10) A description of work done or
is not off scale. Clock failure or adjustments made.
overload is possible.
(11) Notation of outages known to have
A-14. REPORTS. - Special report occurred. Give date, time, and duration if
forms should be developed for each possible.
region. These should be revised from
time to time as required. Record E. MANUFACTURERS' CATALOGS
wherever possible the following data: AND INSTRUCTION BOOKS
(1) Name of customer and A-15. GENERAL. - The technician inspecting
ADP number (if available). the metering installations should be
thoroughly familiar with the publications listed
(2) Time. below which are applicable to equipment for
which he is responsible.
(3) Day.
61 (FIST 3-10 1/92)
A-16. GENERAL ELECTRIC COMPANY. Types MC-23, MC-24, and
MC-25 Phase-Shifting
a. Instruction Books. Transformers . . . . . . GEH-1552B
(1) Single-phase Watt-hour Meters. (4) Watt-hour Demand Meters and
Demand Registers.
Types 1-50 and 1-55 Watt-hour
Meters . . . . . . . . . . . . GEH-1550D Type M-30 Demand
Register . . . . . . . . . . GEH-1529K
(2) Polyphase and Switchboard
Watt-hour Meters. Type M-60 FS-2 Demand
Register . . . . . . . . . . GEH-2778A
Constant and Register
Ratio Data . . . . . . . . . GET-1887B Type M-60 FS-1 Demand
Register . . . . . . . . . . GEH-2768A
V-type Polyphase Watt-hour
Meters . . . . . . . . . . . . . . GET-1191D (5) Demand Meters and Associated
Devices.
Types DS-19 to DS-44
Polyphase Switchboard Types PD-5 to PD-8
Meters . . . . . . . . . . . . GEH-764AC Printing Demand
Meters . . . . . . . . . . . GEH-1038N
DS-50 and DS-60 Series
Switchboard Watt Types PD-55F and PD-57F
hours Meters . . . . . . . . GEH-2762B Printing Demand
Meters . . . . . . . . . . . GEH-2764E
V-60 Series Polyphase
Watt-hour Meters . . . . GEH-2758B Types D-5, D-12, and D-13
Contact Devices . . . . . GEH-224L
(3) Accessories for Watt-hour Meters.
Types D-20 and D-30
Type lB-10 Watt-hour Meter Contact Devices . . . . GEH-2754B
Standard . . . . . . . . . . . GEH-1215C
Type D-41 Impulse
Types MC-21, MC-22, and Generator . . . . . . . . GEH-2767A
MC-27 to MC-34
Phase-Shifting Types DT-3 and DT-4
Transformers . . . . . . . GEH-1537A Totalizing Relays . . . . GEH-828F
Types MC-63, MC-65, MC-66, Type MD-3 Totalizer . . GEH-1050E
and MC-67 Phase-Shifting
Transformers . . . . . . . . . GEH-2766 Type D-51 Impulse
Generator . . . . . . . . . GEH-2781A
(FIST 3-10 1/92) 62
(6) Miscellaneous** Types 1-60-S Watt-hour
Meter . . . . . . . . . . . . GEF-4100B
How to Select Contact
Devices and Impulse (2) Polyphase and Switchboard Watt
Generators . . . . . . . GET-3048A hour Meters.
How to Test and Adjust Types V-3, V-5, and V-6 Poly
G.E. AC Watt-hour phase Watt-hour
Meters . . . . . . . . . . . . GET-813G Meters . . . . . . . . . . . GEF-2721D
Manual of Watt-hour Types V-62, V-63, V-65, V-66,
Meters . . . . . . . . . . . . GET-1840 and V-68 Polyphase Watt
hour Meters . . . . . . . GEF-4132A
Instrument Transformer
Accuracy Standards . . GET-1526 Types V-4, V-7, V-9, V-10,
and V-16 Polyphase Watt
Manual of Instrument hour Meters . . . . . . . GEF-2904B
Transformers . . . . . . . . GET-97C
Type V-64 Polyphase
Instrument Transformer Watt-hour Meter . . . . GEF-4300
Burden Data . . . . . . GET-1725D
DS-50 and DS-60 Series
Manual of Demand Polyphase Switchboard
Meters . . . . . . . . . . . . GET-2327 Watt-hour Meters . . GEF-4139B
Application of Watt-hour Drawout-type Switchboard
Meters . . . . . . . . . . . . GET-1905 Watt-hour Meters Types
IS and DS . . . . . . . . GEF-3159C
Guide for Installing
Watt-hour Meters . . . . GET-2669 (3) Accessories for Watt-hour Meters.
b. Spare Parts Catalogs. Type lB-10 Watt-hour Meter
Standard . . . . . . . . . GEF-3148B
(1) Single-phase Watt-hour Meters.
Photoelectric Watt-hour
Type 1-30 Watt-hour Meter Tester . . . . . . GEF-3705B
Meter . . . . . . . . . . . . GEF-2745D
Photoelectric Watt-hour
Types 1-50 and 1-55 Meter Tester, Catalog
Watt-hour Meters . . . GEF-3590E No. 4153711 . . . . . . . GEF-4329
* Note: GET-2291 Instruction Book provides
information on most of these items.
63 (FIST 3-10 1/92)
(4) Watt-hour Demand Meters and
Demand Registers. c. Address. - The address for securing
the above catalogs and instruction books
Types M-30 and M-31 Demand is:
Registers . . . . . . . . . GEF-3594B
Distribution Services
Type M-60 FS-1 Demand General Electric Company
Register . . . . . . . . . . GEF-4184B Schenectady NY 12305
Type M-60 FS-2 Demand A-17. WESTINGHOUSE ELECTRIC
Register . . . . . . . . . . . GEF-4333 CORPORATION.
(5) Demand Meters and Associated a. Instruction, Operation, and Main-
Devices. tenance Catalogs.
Types PD-5 to PD-8 Printing Watt-hour Meter Calibration
Demand Meters . . . . GEF-3361A Information . . . . . . . . . IL42-100B
Types D-5, D-12, and D-13
Contact Devices . . . . GEF-1967E Switchboard Watt-hour Meters,
Types D2B, etc . . . . . IL42-201.3A
Types D-20 and D-30 Contact
Devices and Type D41 Instructions for Cartridge-Tape
Impulse Generator . . . GEF-4091 Change for Surface Mounted
WR-2 and WR-4
Types PD-55F and PD-57F Recorders . . . . . . . . . IL42-503.5
Printing Demand
Meters . . . . . . . . . . . . . GEF-4165 Flexitest Case (semiflush)
WR-2 and WR-4
Types DT-3 and DT-4 Recorders . . . . . . . . . IL42-503.6
Totalizing Relays . . . GEF-3173B
Types MD-3, MD-4, MD-5, Test Counter for use with WR-2
and MD-6 Outgoing and WR-4 Recorders . IL42-503.4
Contact Devices
D-6 and D-7 . . . . . . . . GEF-3677A
Types WR-2 and WR-4 Demand
Type SS-2 Solid-State Recorders P2, P3 Surface
Impulse Totalizer . . . . . GEI-52440 Mounted Cases . . . . IL42-503.8
Flexitest (semiflush)
Note: Renewal-Parts Bulletins for Watt-hour Meters Case . . . . . . . . . . . . . IL42-503.9
and Demand Meters, GET-2290, provides
information on most of the above meters.
(FIST 3-10 1/92) 64
Type WLT-121 Tape-to-Card CV-1 Impulse Device . . . DB42-950
Translator . . . . . . . . I L42-505.1 A
c. Renewal Parts Catalogs.
WT-1 and WT-2 Pulse Totalizing
Relays . . . . . . . . . . . . IL42-530.6 DB and CB-F Switchboard
Watt-Hour Meters . . . . 42-201A1
Mechanical Pulse Initiators for
use with Watt-Hour Types WR-2C and WR-4C in
Meter . . . . . . . . . . . . . . IL42-950.3
Flexitest Case . . . . 42-565WR-2
CV-1 Impulse Device . IL42-950.1B d. Address. - The address for secur
ing the above catalogs is:
Photoelectric Pulse Initiators,
Types CD-11 and Westinghouse Electric Corporation
CD-21 . . . . . . . . . . . . . IL42-950.4 Meter Division, Raleigh Plant
PO Box 9533
Types WR2C and WR4C in Raleigh NC 27603
Flexitest Case . . . . I L42-565WR2
A-18 BECKMAN INSTRUMENTS, INC.
b. Descriptive Catalogs.
a. Instruction Book.
Mark l Dual Range Demand
Recorders . . . . . . . . . . . DB42-302 Model 6003A-11 Accumulator
(Used in WLT-121 Translator)
Pulse-O-Matic Computerized
Metering Systems . . . . . DB42-550 b. Address. - The address for secur
ing the above catalog is:
Pulse Receivers and
Recorders . . . . . . . . . . . DB42-565
Beckman Instruments, Inc.
Electronic Instrument Division
Pulse Initiators . . . . . . . . DB42-555
2200 Wright Avenue
Richmond CA 94804
Translators . . . . . . . . . . . DB42-570
65 (FIST 3-10 1/92)
A-19. DUNCAN ELECTRIC COMPANY. A-20. EDISON ELECTRIC INSTITUTE.
a. General Information. a. Handbook. - Electrical Metermen's
Handbook, seventh edition
BRT Billing Tape Recorder . . . . 310
b. Address. - The above handbook is
b. instruction Manual, available from:
Type BTR . . . . . . . . . . . . . . . . .860 Edison Electric Institute
750 Third Avenue
c. Address. - The address for securing New York NY 10017
the above materials is:
Duncan Electric Company
Box 180
Lafayette IN 47902
(FIST 3-10 1/92) 66 e US GOVERNMENT PRINTING OFFICE: 1992--836 166
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