Docstoc

Environmental Considerations

Document Sample
Environmental Considerations Powered By Docstoc
					Telecommunications Industry Association                                TR41.7.4-05-11-002M


                                   Document Cover Sheet


Project Number      PN-3-3283RV2

Document Title      Telecommunications - Telephone Terminal Equipment - Electrical, Thermal,
                    Mechanical Environmental Performance Requirements

Source              AST Technology Labs, Inc.

Contact             Name:       Don McKinnon                 Phone:    321-254-0268

                    Complete    1430 Sarno Rd                Fax:      321-254-9511
                    Address:    Melbourne, FL 32935          Email:    dmckinnon@asttechlabs.com
Distribution        TR-41.7.4
Intended Purpose            For Incorporation Into TIA Publication
of Document                 For Information
(Select one)          X     Other (describe) – Post meeting document for review
The document to which this cover statement is attached is submitted to a Formulating Group or
sub-element thereof of the Telecommunications Industry Association (TIA) in accordance with the
provisions of Sections 6.4.1–6.4.6 inclusive of the TIA Engineering Manual dated March 2005, all
of which provisions are hereby incorporated by reference.




                                          Abstract

This document is the result of the November 7, 2005 TIA
TR41.7.4 meeting review of PN-3-3283RV2 draft 05 with
all edits accepted for a clean document, hereby known as
draft 06. This document is for post meeting editorial
reviews by the working group members.

Any editorial updates required to this document shall be
sent to Don McKinnon (dmckinnon@asttechlabs.com) by
December 9, 2005.
                               PN-3-3283RV2

                   TR41.7.4-05-11-002M (Draft 06)

(Working draft 05 TR41.7.4-05-11-001M-All Edits Accepted)


                        (To be ANSI/TIA-571-B)


                           Telecommunications

                   Telephone Terminal Equipment

       Electrical, Thermal, Mechanical Environmental
                  Performance Requirements


Formulated under the cognizance of TIA Subcommittee TR-41.7, Environmental and Safety
Considerations


With the approval of TIA Engineering Committee TR-41, User Premises Telecommunications
Equipment Requirements
Telecommunications Industry Association                                        TR41.7.4-05-11-002M

The TR-41.7.4 Working Group acknowledges the contributions made by the following individuals in
the development of this standard.
           Name                     Representing                 Position (If Applicable)
      Don McKinnon                  AST Technology Labs                           Editor
         Amar Ray                           Sprint
  Chrysanthos Chrysanthou           Telcordia Technologies
       Mike Hopkins                     Thermo Keytek
      Steve Whitesell                       Vtech

The TR-41.7.4 Working Group, which had the technical responsibility during the development of this
standard, had the following participating members.
                           Name                        Representing
                       Dave Stenner                          Advent
                       James Bress                    AST Technology Labs
                        Roger Hunt                           Atlinks
                      Mich Maytum                          Bourns LTD
                     Harry Van Zandt                    ECS Technologies
                     Berndt Martenson                         ETSI
                        Phil Haven                          Littlefuse
                     Greg Slingerland                         Mitel
                      Carl Lindquist                  San-O Industrial Corp.
                         Al Martin                       Tyco Electronics
                     Boris Golubovic                     Tyco Electronics
                       Paul Becker                       Tyco Electronics
                       Randy Ivans                           UL Inc.
                         Al Baum                             Uniden.
                       Steve Kropp                            Vtech
                        Jim Smith                             Wyle
(To be published as TIA-571-B)                               Draft 06                                                       PN-3-3283RV2
                                                        TR41.7.4-05-11-002M

                                                   TABLE OF CONTENTS
1.                   SCOPE ____________________________________________________________ 2
2.                   NORMATIVE REFERENCES ________________________________________ 3
     2.1.       NORMATIVE REFERENCES............................................................................................... 3
     2.2.       INFORMATIVE REFERENCES............................................................................................ 3
3.                   ABBREVIATIONS, ACRONYMS, AND DEFINITIONS __________________ 4
     3.1.       ABBREVIATIONS AND ACRONYMS................................................................................. 4
     3.2.       DEFINITIONS...................................................................................................................... 4
4.                   TECHNICAL REQUIREMENTS ______________________________________ 5
     4.1.       CATEGORIES OF CRITERIA .............................................................................................. 5
     4.2.   GENERAL ........................................................................................................................... 5
          4.2.1. Ambient Test Conditions ........................................................................................ 5
          4.2.2. Test Signals ............................................................................................................. 5
     4.3.   PHYSICAL ENVIRONMENT ............................................................................................... 5
          4.3.1. Impact ...................................................................................................................... 5
          4.3.2. Vibration ................................................................................................................. 7
          4.3.3. Temperature And Humidity .................................................................................... 7
     4.4.   ELECTRICAL ENVIRONMENT .......................................................................................... 9
          4.4.1. AC Short Duration Voltage Sags And Interruptions ............................................... 9
          4.4.2. Extreme AC Voltage Sags And Interruptions ....................................................... 10
          4.4.3. Power Line Faults.................................................................................................. 11
          4.4.4. Lightning Surges ................................................................................................... 12
          4.4.5. Electrostatic Discharge (ESD) .............................................................................. 16
ANNEX A              (INFORMATIVE) – ELECTROMAGNETIC INTERFERENCE ___________ 21
     A.1        RADIO FREQUENCY IMMUNITY (RFI) .......................................................................... 21
     A.2        EMISSIONS ....................................................................................................................... 21
ANNEX B              (INFORMATIVE) RATIONALE FOR TELEPHONE LINE OVERVOLTAGE
                     TESTS ____________________________________________________________ 22
     B.1        SOURCES OF OVERVOLTAGE ........................................................................................ 22
     B.2        ANALYSIS OF LIMITING OVERVOLTAGE CONDITIONS .............................................. 22
     B.3        PERFORMANCE OF TELECOMMUNICATIONS USER PREMISES EQUIPMENT ............ 23
     B.4        2-LINE AND 4-WIRE CIRCUITS ...................................................................................... 23
     B.5        MULTIPLE SETS .............................................................................................................. 23
     B.6        WIRING SIMULATION ..................................................................................................... 24
     B.7        PRIMARY PROTECTOR COORDINATION....................................................................... 24
     B.8        TEST POINTS.................................................................................................................... 24
     B.9        TEST CONDITIONS .......................................................................................................... 25
     B.10       FAILURE CONDITIONS .................................................................................................... 25
ANNEX C              (INFORMATIVE) RATIONALE FOR SURGES ________________________ 26


                                                                     i
PN-3-3283RV2                                          Draft 06                                 (To be published as TIA-571-B)
                                                   TR41.7.4-05-11-002M
   C.1     SOURCES OF SURGES ...................................................................................................... 26
   C.2     TRADITIONAL TELECOM SURGE SPECIFICATION ........................................................ 26
   C.3     SURGE TYPES ................................................................................................................... 27
         C.3.1  L-type (Longitudinal) ............................................................................................ 27
         C.3.2  M-type (Metallic) ................................................................................................... 27
         C.3.3  P- type (Power) ...................................................................................................... 27
         C.3.4  T-type (Transverse)................................................................................................ 27
         C.3.5  I-type (Intrabuilding) ............................................................................................. 27
   C.4     OPEN CIRCUIT VOLTAGE AND VOLTAGE WAVESHAPE .............................................. 27
   C.5     SHORT CIRCUIT CURRENT AND CURRENT WAVESHAPE ............................................ 28
   C.6     SURGE STUDIES AND DATA ........................................................................................... 28
         C.6.1  Telephone line monitoring ..................................................................................... 28
         C.6.2  Survey data ............................................................................................................ 28
   C.7     STANDARDS ON SURGES ................................................................................................ 29
         C.7.1  FCC Rules, Part 68 ................................................................................................ 29
         C.7.2  CCITT Recommendation K.17 .............................................................................. 29
         C.7.3  ANSI/IEEE C62.45 ................................................................................................ 29
         C.7.4  IEC 61000-4-5........................................................................................................ 29
   C.8     SURGE LIKELIHOOD ........................................................................................................ 30
         C.8.1  Level A and level B ............................................................................................... 30
         C.8.2  Level C ................................................................................................................... 30
   C.9     SURGES FOR TELECOMMUNICATIONS EQUIPMENT ................................................... 30
         C.9.1  Metallic .................................................................................................................. 30
         C.9.2  Longitudinal ........................................................................................................... 30
         C.9.3  Power ..................................................................................................................... 30
         C.9.4  Transverse .............................................................................................................. 30
         C.9.5  Ground ................................................................................................................... 30
ANNEX D         (INFORMATIVE) - GROUNDING PRACTICES ________________________ 31
ANNEX E         (INFORMATIVE) - TELEPHONE LINE VOLTAGES AND CURRENTS ___ 32
ANNEX F         (INFORMATIVE) - STEADY STATE POWER INDUCTION _____________ 33




                                                                   ii
(To be published as TIA-571-B)                             Draft 06                                                    PN-3-3283RV2
                                                      TR41.7.4-05-11-002M
                                                         Table of Figures
Figure 1 – Transient Voltage Interruption and Sag Criteria .................................................................. 9
Figure 2 – Application of Surge Generators ........................................................................................ 14


                                                          Table of Tables
Table 1 – Range of Temperature & Relative Humidity ......................................................................... 8
Table 2 – Temperature & Relative Humidity Test Points...................................................................... 8
Table 3 – Lightning type abbreviations................................................................................................ 12
Table 4 – High Voltage Surges ............................................................................................................ 15
Table 5 – ESD response mode distribution .......................................................................................... 17
Table 6 – ESD Discharge voltages and methods ................................................................................. 18
Table 7 – Test voltage vs. altitude multipliers ..................................................................................... 19




                                                                  iii
     (To be published as TIA-571-B)              Draft 06                                  PN-3-3283RV2
                                            TR41.7.4-05-11-002M
 1                                              Foreword
 2   This standard is one of a series of technical standards on telecommunications user premises
 3   telecommunications equipment prepared by TIA Engineering Committee TR-41. It will be useful to
 4   anyone engaged in the manufacture, purchasers and users of such equipment or devices.
 5
 6   This standard describes environmental conditions in which could be detrimental to such equipment.
 7   The conditions are based on characteristics at the Customer Interface.
 8
 9   Some of the tests prescribed in this standard may involve the presence of hazardous voltages and
10   currents or other potential dangers to test personnel. Some of these hazards have been identified, and
11   appropriate warnings have been included in the text prescribing such tests. However, appropriate
12   safety precautions are always recommended when performing any laboratory test.
13




                                                     1
     PN-3-3283RV2                           Draft 06                (To be published as TIA-571-B)
                                         TR41.7.4-05-11-002M

14   1. SCOPE
15   This document establishes environmental performance criteria for Customer Premises Equipment
16   (CPE), such as Telephones, Modems, portable PBX, Routers, Set top Box, Alarm Systems, etc. It
17   defines the physical and electrical conditions under which the equipment shall continue to
18   demonstrate basic functionality.
19
20   This performance document may cover some topics addressed in regulatory or safety documents.
21   Compliance to this document is not intended to infer regulatory or safety compliance.
22
23   This document does not include the following types of equipment: Stationary equipment such as
24   Switches, DSLAM or Large PBX equipment, IP Gateways, etc.




                                                  2
     (To be published as TIA-571-B)              Draft 06                                 PN-3-3283RV2
                                            TR41.7.4-05-11-002M

25   2. NORMATIVE REFERENCES
26   The following standards contain provisions, which, through reference in this text, constitute
27   provisions of this Standard. At the time of publication, the editions indicated were valid. All
28   standards are subject to revision, and parties to agreements based on this Standard are encouraged to
29   investigate the possibility of applying the most recent editions of the standards indicated below.
30   ANSI and TIA maintain registers of currently valid national standards published by them.

31   2.1.    NORMATIVE REFERENCES
32   1. Code of Federal Regulations, Federal Communication Commission Rules and Regulations, Part
33      68, Connection of Terminal Equipment to the Telephone Network.
34   2. UL 60950-1, Safety of Information Technology Equipment
35   3. T1.401-2001, Interface Between Carriers and Customer Installations - Analog Voicegrade
36      Switched Access Lines Using Loop-Start and Ground-Start Signaling
37   4. International Electrotechnical Commission (IEC) Publication 61000-4-5: Electromagnetic
38      Compatibility (EMC) - Part 4 Testing and Measurement Techniques - Section 5 Surge Immunity
39      Test
40   5. ITU-T Recommendation K.21-2003, Resistibility of telecommunication equipment installed in
41      customer premises to overvoltages and overcurrents.
42   6. International Electrotechnical Commission (IEC) Publication 61000-4-2:1995, Electromagnetic
43      Compatibility (EMC) - Part 4 Testing and measurement techniques - Section 2 Electrostatic
44      discharge test - Basic EMC Publication
45
46   2.2.    INFORMATIVE REFERENCES
47   1. TIA-631-A (1996), Telecommunications - Telephone Terminal Equipment - Radio Frequency
48      Immunity Requirements for Equipment Having an Acoustic Output
49   2. ANSI C84.1-1995, Electrical Power Systems and Equipment - Voltage Rating (60Hz)
50   3. Code of Federal Regulations, Federal Communications Commission Rules and Regulations, Part
51      15, Radio Frequency Devices.
52   4. TIA-470.210-C-2004, Telecommunications Telephone Terminal Equipment Resistance and
53      Impedance requirements for Analog Telephones
54




                                                    3
     PN-3-3283RV2                             Draft 06                   (To be published as TIA-571-B)
                                           TR41.7.4-05-11-002M

55   3. ABBREVIATIONS, ACRONYMS, AND DEFINITIONS
56   For the purpose of correct interpretation of this document, the following key technical terms and
57   abbreviations apply. Terms used in the document but not defined in this section shall be interpreted
58   according to their internationally accepted definition.

59   3.1.    ABBREVIATIONS AND ACRONYMS
60   1. CPE           Customer Premises Equipment
61   2. PBX           Private Branch Exchange
62

63   3.2.    DEFINITIONS
64   Basic Functionality             CPE ability to perform Send, Receive, Dialing and Alerting
65   Earth (Ground)                  A remote location considered to be at zero potential. Used
66                                   interchangeably with “ground.”
67   Grounding Conductor             The conductor connecting the equipment’s frame or grounding
68                                   terminal to a building’s ground system.
69   Network Interface or Demarcation Point The point of interconnection between telephone company
70                                  communications facilities and terminal equipment, protective
71                                  apparatus or wiring at a subscriber's premises. The network interface
72                                  or demarcation point is located on the subscriber’s side of the
73                                  telephone company's protector, or the equivalent thereof in cases
74                                  where a protector is not employed, as provided under the local
75                                  telephone company’s reasonable and nondiscriminatory standard
76                                  operating practices.
77   Customer Premises Equipment Communications equipment located on customer premises at the end
78                               of the communications link, that is used to permit the stations
79                               involved to accomplish the provision of telecommunications or
80                               information services. (Telephones, Modems, PBX, Routers, Set top
81                               Box, Alarm Systems, etc)
82




                                                      4
      (To be published as TIA-571-B)               Draft 06                                  PN-3-3283RV2
                                              TR41.7.4-05-11-002M

 83   4. TECHNICAL REQUIREMENTS
 84   4.1.    CATEGORIES OF CRITERIA
 85   Three types of requirements are specified in this standard; Mandatory and Recommended.
 86   1. Mandatory requirements are designated by the terms “shall” and “shall not”.                     These
 87      requirements are used to indicate conformity in which no deviation is permitted.
 88   Recommended requirements are designated by the terms “should” and “should not”. These
 89      requirements generally relate to compatibility or performance advantages towards which future
 90      designs should strive.
 91   Desirable requirements are designated by the terms “may” and “may not”. These requirements are
 92      used to indicate an action that is permitted within the limits of the standard.
 93

 94   4.2.    GENERAL
 95   4.2.1. Ambient Test Conditions
 96   Unless otherwise stated, the Ambient conditions (room temperature and humidity) are defined as
 97   +22°C ± 3°C (+68 to 77°F) and 40% ± 20% relative humidity. Ambient temperature is measured at a
 98   distance of 15 inches (38 cm) in front of the equipment, at half the height of the equipment, after the
 99   air temperature has stabilized.
100
101   4.2.2. Test Signals
102   All test signals shall be within ± 1% of the specified nominal value unless otherwise indicated.
103
104
105   4.3.    PHYSICAL ENVIRONMENT
106   4.3.1. Impact
107   4.3.1.1.  Requirement
108   The CPE shall not exhibit the following conditions after impact testing, packaged or unpackaged:
109   1. Cabinet separation
110   2. Loose objects inside cabinet(s)
111   3. Loss of functionality
112
113   Parts intended for removal such as battery door or memo covers shall not be considered a failure if
114   such parts can be installed as intended. If they cannot be installed as intended then it shall be
115   considered a failure.
116




                                                      5
      PN-3-3283RV2                               Draft 06                    (To be published as TIA-571-B)
                                              TR41.7.4-05-11-002M
117   4.3.1.2.     Procedure
118   Impact surfaces are chosen such that they are perpendicular to the direction of motion of the unit at
119   the time of impact. Packaged or unpackaged tests shall be performed as follows:
120    Face Drop. The unit is dropped such that the face struck is approximately parallel to the impact
121        surface.
122    Corner Drop. The unit is dropped such that, upon impact, a line from the struck corner to the
123        center of gravity of the packaged equipment is approximately perpendicular to the impact
124        surface.
125    Edgewise Drop. The unit is positioned on a flat surface. One edge of the rest face is supported by
126        a block so that the rest face makes an angle of 20°with the horizontal. The opposite edge is lifted
127        the designated height above the test surface and dropped.
128    Cornerwise Drop. The unit is positioned on a flat test surface. One corner of the rest face is
129        supported by a block so that the rest face makes an angle of 20°with the horizontal. The opposite
130        corner is lifted the designated height above the test surface and dropped.
131    Random Drop. The unit is positioned prior to release to ensure as nearly as possible that for
132        every six drops there is one impact on each of the six major surfaces and that the surface to be
133        struck is approximately parallel to the impact surface.
134
135   4.3.1.3.   Equipment Packaged For Shipment - Drop Stresses
136   Impact shall be made onto a concrete surface. If after six or more successive drops a package has
137   sustained visible damage, the equipment under test may be repackaged before the packaged drop tests
138   are resumed.
139   1. Packaged weight of 0-20 lb. (0-9 kg): One 30-inch (76 cm) face drop on each face and one 30-
140       inch (76 cm) corner drop on each corner.
141   2. Packaged weight of 20-50 lb. (9-23 kg): One 24-inch (61 cm) face drop on each face and one 24-
142       inch (61 cm) corner drop on each corner.
143   3. Packaged weight of 50-100 lb. (23-45 kg): One 21-inch (53 cm) face drop on each face and one
144       21-inch (53 cm) corner drop on each corner.
145
146   4.3.1.4.    Equipment Unpackaged - Drop Stresses
147   Impact shall be made onto concrete covered with 3 mm (0.125-inch) asphalt tile or similar surface.
148   1. Hand-Held Items. Normally Used at Head Height: Six random drops from a height of 152 cm (60
149       inches)
150   2. Table (Desk) Top Equipment or equipment capable of connecting to Table Top Equipment, 0-5
151       kilograms (0-11 lb.): Six random drops from a height of 30 inches (76 cm).
152   3. Other Equipment: The equipment is dropped as follows:
153       A) Equipment weight of 0-9 kg (0-20 lb.): One 6-inch (152 mm) face drop on each designated
154            rest face, one 3-inch (76 mm) face drop on all other faces and one 3-inch (76 mm) corner
155            drop on each corner.
156       B) Equipment weight of 9-23 kg (20-50 lb.): One 4-inch (102 mm) face drop on each
157            designated rest face, one 2-inch (51 mm) face drop on all other faces and one 2-inch (51 mm)
158            corner drop on each corner.
159       C) Equipment weight of 23-45 kg (50-100 lb.): One 2-inch (51 mm) face drop on each
160            designated rest face, one edgewise drop and one cornerwise drop from a height of 2 inches
161            (51 mm) on each edge and corner adjacent to the rest face.
162




                                                         6
      (To be published as TIA-571-B)              Draft 06                                  PN-3-3283RV2
                                             TR41.7.4-05-11-002M
163   4.3.2. Vibration
164   4.3.2.1.    Equipment shipped packaged or unpackaged
165   The following sinusoidal vibration simulation of transportation vibration shall be applied to the unit
166   once in each of three orthogonal directions:
167   1. A frequency sweep shall be at an acceleration level of 5 m/s2 peak, from 5 to 100 Hz and
168       conducted at a sweep rate of 0.1 octave per minute (approximately 45 minutes)
169   2. A frequency sweep at an acceleration level of 15 m/s2 peak from 100 to 500 Hz and conducted at
170       a rate of 0.25 octave per minute (approximately 10 minutes).
171
172   4.3.3. Temperature And Humidity
173   4.3.3.1.     Storage Thermal Soak
174   CPE in its non-operational state shall be subjected to storage conditions by soaking it continuously
175   for at least 24 hours stabilization at each of the following points:
176   1. -40°C (-40°F) and any convenient humidity (the low temperature point).
177   2. +66°C (+150°F) at 15% RH (the high temperature point).
178   3. +32°C (+90°F) at 90% RH (the high relative humidity point).
179
180   After each 24-hour soak, the CPE shall be returned to the ambient conditions without causing
181   condensation.
182   It is desirable to soak equipment at the high humidity point for 96 hours
183   4.3.3.1.1. Requirement
184   After being subjected to each Thermal Soak condition, the CPE shall provide basic functionality 2
185   hours after returning to ambient conditions.
186
187   4.3.3.2.   Storage Thermal Shock
188   CPE in its non-operational state shall be subjected to three of each the following thermal shocks (six
189   total):
190   1. High Temperature to Room Temperature: After reaching temperature stabilization at +66°C
191       (+150°F) and a relative humidity of 15)%, the equipment shall be subjected to a sudden change
192       to ambient conditions.
193   2. Low Temperature to Room Temperature: After reaching temperature stabilization at -40°C
194       (-40°F) and any convenient humidity, the equipment shall be subjected to a sudden change to
195       ambient conditions.
196   4.3.3.2.1. Requirement
197   The CPE shall maintain basic functionality after being subjected to each Thermal Shock condition
198   and returning to ambient conditions.
199   After being subjected to each Thermal Shock condition, the CPE shall provide basic functionality 2
200   hours after returning to ambient conditions.
201
202   4.3.3.3.   Storage Cycling
203   The packaged CPE in its non-operational state shall be cycled for three times at a non-condensing
204   rate through the following temperature and humidity conditions:
205   1. 30 minutes at +66°C (+150°F) and 15 percent RH, followed by
206   2. 30 minutes at +32°C (+90°F) and 90 percent RH, followed by
207   3. 30 minutes at -40°C (-40°F) and any convenient humidity.
208
209   After the three cycles are completed, the CPE shall be returned to the ambient conditions.

                                                      7
      PN-3-3283RV2                              Draft 06                       (To be published as TIA-571-B)
                                             TR41.7.4-05-11-002M
210
211   4.3.3.3.1. Requirement
212   After being subjected to the three cycles condition, the CPE shall provide basic functionality 2 hours
213   after returning to ambient conditions.
214
215
216   4.3.3.4.    Operating Temperature And Humidity Conditions
217   The applicable range of temperature and humidity that the CPE is expected to encounter is specified
218   in Table 1.
219         Note: The table below was derived from T1.304.
220
221                          Table 1 – Range of Temperature & Relative Humidity
                       Condition                             Temperature Limits                   Humidity
                                                                                                   Limits
       Controlled Environment
        Normal (continuous)                               5°C (41°F) to 40°C (104°F)              5% to 85%
        Exceptional (short-term)                         -5°C (23°F) to 49°C (120°F)              5% to 90%
       Partially Controlled Environment                 -20°C (23°F) to 55°C (131°F)              5% to 95%
                                                        -40°C (-40°F) to 65°C (149°F)
       Uncontrolled Environment                                                                   5% to 95%
                                                     (Includes the effects of solar loading)
222
223   The temperature and humidity test points that cover the environmental conditions identified in Table
224   1 are given in Table 2.
225
226                        Table 2 – Temperature & Relative Humidity Test Points
                  Environmen                                   Partially
                                    Uncontrolled                                     Controlled
                       t                                      Controlled

                      Cold         –40 °C (–40 °F)           –20°C (–4°F)            5°C (41°F)
                                     50% RH                   50% RH               ~50% RH

                      Damp          32°C (90°F)               32°C (90°F)           27°C (81°F)
                                      90% RH                   90% RH                 90% RH

                       Hot          60°C (140°F)             46°C (115°F)           40°C (104°F)
                                      19% RH                   39% RH                 43% RH

                       Dry          65°C (140°F)             46°C (115°F)           40°C (104°F)
                                      10% RH                   10% RH                 10% RH
227
228   4.3.3.4.1. Requirement
229   The CPE shall be tested to the applicable intended use Uncontrolled, Partially Controlled, or
230   Controlled. The CPE basic functionality shall be verified after the equipment has been at each
231   environmental test point for at least 6 hours.
232




                                                         8
      (To be published as TIA-571-B)               Draft 06                                  PN-3-3283RV2
                                              TR41.7.4-05-11-002M

233   4.4.    ELECTRICAL ENVIRONMENT
234   4.4.1. AC Short Duration Voltage Sags And Interruptions
235   Commercial ac power may experience transient voltage interruptions lasting for less than one cycle
236   and short duration voltage sags lasting for several cycles. Figure 1 shows the transient voltage
237   interruption and sag criteria for which equipment using commercial ac power is expected to operate.
238   The criteria are expressed in terms of the percentage of nominal voltage as a function of time and
239   equivalent number of cycles of ac power. A nominal system voltage of 120 VRMS shall be assumed.
240          Note: Nominal system voltage is defined in ANSI C84.1
241   4.4.1.1.   Requirement
242   1. The CPE in any normal operating state shall not change state (e.g. Talk state, dialing, etc.) or lose
243       any stored information for any single voltage sag, dual voltage sag separated by intervals of 2 to
244       5 seconds, or transient voltage interruption in the Operation Required region of Figure 1.
245   2. It is desirable that CPE not change state or lose any stored information for any single voltage sag
246       or dual voltage sag separated by intervals of 2 to 5 seconds in the Operation Desirable region of
247       Figure 1.
248          Notes:
249             1. Typical usage conditions, not worse case power consumption scenarios, should be
250                 used when testing for compliance
251             2. Two or possibly three voltage sags could occur in succession. Such sags would
252                 normally be separated by intervals of 2 to 5 seconds or longer. Two or three voltage
253                 sags could occur in succession. Such sags would normally be separated by intervals of
254                 2 to 5 seconds or longer. It is recommended that 5-second intervals be used when
255                 applying multiple sags for compliance testing.




                                                                             20
256
257
                                            100
                         Figure 1 – Transient Voltage Interruption and Sag Criteria
258



                                                       9
      PN-3-3283RV2                               Draft 06                    (To be published as TIA-571-B)
                                              TR41.7.4-05-11-002M
259   4.4.1.2.   Method of Test
260   All items refer to Figure 1.
261   1. Perform 3 test points in the 16.7 ms to 20 ms region at 80% (96 Vrms), 50% (60 Vrms) and 20%
262       (24 Vrms) of nominal voltage.
263   2. Perform at least 5 test points each in the >20 ms to 125 ms region at 55% (66 Vrms) and 45% (54
264       Vrms) of nominal voltage.
265   3. Perform at least 5 test points each in the >125 ms to 500 ms region at 75% (90 Vrms) and 55%
266       (66 Vrms) of nominal voltage.
267   4. Perform at least 5 test points each in the >500 ms to 1000 ms region at 85% (102 Vrms) and 75%
268       (90 Vrms) of nominal voltage.
269   5. Perform at least 5 test points each in the >1000 ms to 2000 ms region at 90% (108 Vrms) and
270       80% (96 Vrms) of nominal voltage.
271
272   4.4.2. Extreme AC Voltage Sags And Interruptions
273   Commercial ac power may experience extreme voltage sags and interruptions. Extreme voltage sags
274   and interruptions are defined when the voltage drops into the Operation Not Required region of
275   Figure 1.
276
277   4.4.2.1.   Requirement
278   1. The CPE is permitted to change state (e.g. drop the call, reset, etc.) but shall resume
279       functionality, without user intervention, after any single voltage sag or dual voltage sag separated
280       by intervals of 2 to 5 seconds in the Operation Not Required region of Figure 1.
281   2. The CPE is permitted to change state (e.g. reset, etc.) but shall resume functionality, without user
282       intervention, after any long term complete voltage interruptions (zero volts) greater than 2
283       seconds.
284
285   4.4.2.2.   Method of Test
286   All items refer to Figure 1.
287   1. Perform at least 3 test points each in the >20 ms to 125 ms region at 0% (0 Vrms) of nominal
288       voltage.
289   2. Perform at least 3 test points each in the >125 ms to 500 ms region at 0% (0 Vrms) of nominal
290       voltage.
291   3. Perform at least 3 test points each in the >500 ms to 1000 ms region at 0% (0 Vrms) of nominal
292       voltage.
293   4. Perform at least 4 test points each in the >1000 ms to 2000 ms region at 0% (0 Vrms) of nominal
294       voltage.
295   5. Perform at least 5 test points each in the >2000 ms to 5000 ms region at 0% (0 Vrms) of nominal
296       voltage.
297




                                                        10
      (To be published as TIA-571-B)               Draft 06                                   PN-3-3283RV2
                                              TR41.7.4-05-11-002M
298   4.4.3. Power Line Faults
299   4.4.3.1.   General
300   During power line fault conditions (which may induce high voltages into telephone lines) or with a
301   power line cross (metallic contact between power conductors and telephone cables), protectors
302   normally limit potentials appearing between the tip and ring conductors (or between tip/ring and
303   ground) to less than 600 volts rms. In most cases, power-system fault detectors will limit the
304   duration of such voltages to 5 seconds. However, high resistance faults can last indefinitely. Such
305   fault conditions can cause a protector to permanently short either the tip or the ring terminal to
306   ground, in which case the fault voltage may appear as a metallic voltage. Test methods for
307   evaluating equipment during over-voltage conditions are given in UL-60950-1. Rationale for the test
308   methods is given in Annex B.
309
310   4.4.3.2.   Short Term Power Induction
311   The CPE in the on-hook idle and off-hook operating states may experience short-term power
312   induction on the telephone line.
313
314         Note: See ITU K.21 for additional information.
315
316   4.4.3.2.1. Requirement
317   CPE shall provide basic functionality after being subjected to the test conditions specified below
318   when the test signal of 600 Vrms, 60 Hz, limited to 1 A short circuit for 200 ms. If the CPE contains
319   a voltage-limiting device, the test shall be repeated using an applied rms voltage that is 0.707 times
320   the maximum operating threshold of the voltage-limiting device
321   The CPE is not required to operate correctly during the test and is allowed to change states as a result
322   of the test.
323
324   4.4.3.2.2. Method of Test
325   1. Place the CPE in the On-hook state.
326   2. Apply the test signals:
327       A. Tip to Ground, Ring Grounded, then
328       B. Ring to Ground, Tip Grounded, then
329       C. Tip to Ground and Ring to Ground simultaneously
330   3. Repeat a total of five times.
331   4. Repeat steps 2 and 3 with the CPE in the Off-hook state.
332




                                                      11
      PN-3-3283RV2                               Draft 06                  (To be published as TIA-571-B)
                                              TR41.7.4-05-11-002M
333   4.4.4. Lightning Surges
334   4.4.4.1.   General
335   Lightning can induce high-voltage surges on leads connected to exposed outside plant facilities (Tip
336   and Ring), on power conductors and on grounding conductors.
337   Typical connections for applying the surges are shown in figure 3. The EUT shall be dc powered and
338   the normal operating interfaces shall be applied to the telephony leads, including the leads being
339   surged, unless stated otherwise.
340         Note: Appropriate care should be taken to ensure that powering circuits and loop feed circuits
341                used to power the equipment and interfaces do not significantly affect the surge
342                presented to the EUT.
343
344   The types of surges to apply are defined as follows:
345   1. Type P surges are applied to branch circuit power connections of the terminal equipment with the
346      equipment powered. Surges are applied between:
347       the phase conductor and neutral conductor,
348       the phase conductor and grounding conductor, and
349       the phase/neutral conductors and grounding conductor (common mode).
350   2. Type M surges are applied to all outside plant tip-ring leads of the terminal equipment. For each
351      pair of tip-ring connection points, surges are applied between Tip and Ring or, for equipment that
352      has a grounding conductor, surges are applied between Tip and Ring with Ring grounded, and
353      then applied between Tip and Ring with Tip grounded.
354   3. Type L surges are applied to all outside plant tip-ring leads of terminal equipment that has a
355      grounding conductor. For each pair of tip-ring connection points, surges are applied between tip-
356      ring simultaneously and the grounding conductor.
357   4. Type T surges are applied to branch circuit power connections and all outside plant tip-ring leads
358      of the terminal equipment with the equipment powered. Surges are applied between the
359      phase/neutral conductors and simplexed tip-ring leads. The grounding conductor (if one exists) is
360      connected to simplexed tip-ring.
361   5. Type I surges are applied to all tip-ring leads of terminal equipment that has a grounding
362      conductor and is subject only to intrabuilding surges. For each pair of tip-ring connection points,
363      surges are applied between tip-ring simultaneously and the grounding conductor.
364
365   Abbreviations used in this section are as follows:
366                                 Table 3 – Lightning type abbreviations
                         Conductor abbreviations                         Surge type abbreviations
             L = Line (“hot” or phase) conductor of power line           Type P = Power
             N = Neutral conductor of power line                         Type M = Metallic
             G = Grounding conductor                                     Type L = Longitudinal
             T = Tip                                                     Type T = Transverse
             R = Ring                                                    Type I = Intrabuilding
             solidus (/) means both conductors simultaneously
             (longitudinal or common mode)
367
368




                                                           12
      (To be published as TIA-571-B)              Draft 06                                  PN-3-3283RV2
                                             TR41.7.4-05-11-002M
369   4.4.4.2.  Requirement
370   1. The CPE shall have basic functionality after all the following applicable surges per Table 4: P1,
371       M1, L1, T1, I1
372   2. The CPE should have basic functionality for all the following applicable surges per Table 4: P2,
373       M2, M3, L2, L3, T2
374
375   4.4.4.3.    Method Of Test
376   The surges are applicable in all operating states of the CPE under test including connections to other
377   equipment and grounding options. If the CPE uses a detachable line cord for its tip-ring connections,
378   a test line cord having no more than one-half ohm per conductor shall be used to connect the
379   equipment to the surge generator. CPE states that affect compliance but cannot be achieved by
380   normal means of power shall be achieved by artificial means. Any magnitude of voltage up to the
381   peak level specified is applicable for equipment that has voltage-limiting circuitry. Sufficient time
382   shall be allowed between surges to prevent cumulative heating of components.
383
384




                                                     13
      PN-3-3283RV2                                        Draft 06                    (To be published as TIA-571-B)
                                                       TR41.7.4-05-11-002M

           Power    1
                    +/–                        L
            Line
           Surge                                   CPE
          Generator                           N G

            G                              disconnect CPE                                     ground
                                               ground if                                      switch
                                                present                           1 +/–
                                                                    Telephone                            T
                                                                       Line
                a) P-1 Testing (TIA-968-A)                            Surge
                                                                    Generator                               CPE
                                                                      G
                                                                                                         R      G

                      1
          Power       +/–              L
           Line
          Surge
                                           CPE                       d) M-1 & M-2 (TIA-968-A) and M-3 Testing
         Generator                     N           G
                        2*
                      +/–
            G

                             * disconnect terminal 2
                                for L-to-G surge                     Telephone       1
                                                                                                         T
                                                                        Line        +/–
                   b) P-2 Testing
                                                                       Surge
                                                                                                            CPE
            (Combination Wave Generator)                                            2                    R
                                                                     Generator      +/–                         G
                                                                          G



                                                         3
           Power        1
                       +/–         L               T
            Line                                                      e) L-1 (TIA-968-A) , L-3, and I-1 Testing
           Surge                       CPE               3               (L-3 uses 10 x 1000 µs generator)
                        2
          Generator                N               R
                       +/–                 G                                 (I-1 uses 2 x 10 µs generator)
            G
                                           *
                        * connect to EUT ground if present

                                                                           Power       1
                     c) T-1 and T-2 Testing                                                             T
                                                                                      +/–
                  (Combination Wave Generator)                              Line             3             CPE
                                                                           Surge       2
                                                                                                        R
                                                                          Generator   +/–                       G
                                                                                            3
                                                                              G


                                                                                   f) L-2 Testing (TIA-968-A)

385
386    [Diagram for Intra-building (G surge) has been removed and figure modified and resequenced as
387                                                required
388                                 Figure 2 – Application of Surge Generators
389



                                                               14
      (To be published as TIA-571-B)              Draft 06                                 PN-3-3283RV2
                                             TR41.7.4-05-11-002M
390   Surge parameters are given in the following table.
391                                     Table 4 – High Voltage Surges
                                                                                             Number of
             Type         Peak Voltage1)    Peak Current2)    Application      Between      Surges, each
                                                                   3)
                             (volts)          (amperes)                                       polarity
              P-1           See TIA-968-A clause 4.2.4.1       Fig. 3 a)        L-to-N            8
                                                                               L-to-N,
              P-2              6,000             3,000         Fig. 3 b)       L-to-G,            4
                                                                              L/N-to-G
                            See TIA-968-A clause 4.2.3.1        Fig. 3 d)
             M-1                                                                                  8
                                     (Type B)                  10x700 s
                            See TIA-968-A clause 4.2.2.1        Fig. 3 d)
             M-2                                                                T-to-R            4
                                     (Type A)                  10x560 s
                                                                Fig. 3 d)
             M-3               1,000             100                                              1
                                                              10x1000 s
                            See TIA-968-A clause 4.2.3.2        Fig. 3 e)
              L-1                                                                                 8
                                     (Type B)                  10x700 s
                            See TIA-968-A clause 4.2.2.2        Fig. 3 e)
              L-2                                                             T/R-to-G            4
                                     (Type A)                  10x560 s
                                                                Fig. 3 e)
              L-3              1,000           100/lead                                           1
                                                              10x1000 s
              T-1              2,500             500           Fig. 3 c)                          8
                                                                             L/N-to-T/R
              T-2              5,000             1,000         Fig. 3 c)                          4
                                                             Fig. 3 e)
              I-1              1,500             100                       T/R-to-G            1
                                                             2x10 s
392   1. Peak voltage is measured at the output terminals of the surge generator with the output
393      terminated in at least 10,000 ohms.
394   2. Peak current is measured at the output terminals of the surge generator with the output
395      terminated in a short circuit.
396   3. The waveshape (where specified) applies to both open circuit voltage and short circuit current,
397      and gives the maximum rise time to peak and the minimum decay time to half-peak. . The current
398      waveform decay to half peak should range between the minimum requirement and two times the
399      minimum requirement for all load values from 0 ohms to 10,000.
400
401   All tests shall be conducted in accordance with the IEC 61000-4-5 and the specific requirements of
402   this standard. The surge generator parameters, test set-up, and procedure for surging equipment given
403   in IEC 61000-4-5 shall be used to the extent practicable.
404




                                                     15
      PN-3-3283RV2                                Draft 06                 (To be published as TIA-571-B)
                                             TR41.7.4-05-11-002M
405   4.4.5. Electrostatic Discharge (ESD)
406   4.4.5.1.    General
407   Electrostatic Discharge (ESD), either directly to equipment or indirectly to some nearby object, can
408   be a significant cause of equipment failure or malfunction. In a network such as ISDN, the adverse
409   effects of ESD on one piece of equipment can propagate to others connected to the network.
410   Equipment can be susceptible to ESD effects at all stages of storage, installation, testing, operation,
411   adjustment, maintenance, and repair.
412
413   An electrostatic charge may be developed on the human body, furnishings, and other objects as a
414   result of everyday actions and activities. The simple act of walking on a carpet or other insulating
415   flooring material can cause a charge to build up on an individual. The rolling or sliding of furnishings
416   such as carts and chairs across the floor, as well as contact with synthetic fabrics used in clothing and
417   furniture upholstery can generate large electrostatic potentials.
418
419   While it may not be possible or practical to protect equipment from the maximum ESD that may be
420   experienced, the intent of ESD testing is to stress equipment with typical electrostatic discharges.
421   All tests shall be conducted in accordance with the IEC 61000-4-2 and the specific requirements of
422   this standard.
423
424   The user’s perception of performance for equipment after a discharge, other than no equipment
425   response at all, falls into one of the following categories:
426       A) Non-recoverable: The user experiences a loss of expected service, such as equipment failure,
427          and loss or corruption of stored information. For example, the equipment may be damaged
428          (typically a semiconductor) or may experience a permanent processor lock-up.
429       B) Recoverable: The user perceives the equipment to have malfunctioned and must take some
430          action that involves ordinary use to recover, e.g., pressing a DISPLAY button to reset a
431          display or power cycling. Voice transmission drop-out that exceeds 1 second, or loss of a call
432          in progress may be also considered as recoverable.
433       C) Temporary: The user perceives a temporary loss of performance (for example, an audible
434          click, flicker on a video screen, data transmission errors that do not exceed one errored
435          second or transmission drop-out that does not exceed 1 second), but normal service is not
436          disrupted.
437   4.4.5.2.    ESD Simulators
438   1. Type 1 (IEC model): The test network consists of a 150-pF capacitor discharging through a 330-
439       ohm resistor1. This represents a human discharge through a small hand-held metallic object.
440   2. Type 2 (Human Body Model, or HBM): This represents a human discharge through a hand. The
441       test network consists of a 100-pF capacitor discharging through a 1500-ohm resistor2.
442




      1   The waveshapes and calibration methods are given in IEC 61000-4-2 .
      2    A calibration method is given in MIL-STD-883C, Test Methods and Procedures for
            Microelectronics.


                                                         16
      (To be published as TIA-571-B)                Draft 06                                  PN-3-3283RV2
                                               TR41.7.4-05-11-002M
443   4.4.5.3.  Requirements
444   3. The response of equipment to a static discharge is of a statistical nature. The equipment shall not
445       exceed the following response mode distribution for each test point.
446
                         Non-Recoverable            Recoverable              Temporary
                              0%                       10%                     100%
447                                 Table 5 – ESD response mode distribution
448   4. The entries in the table apply to each test point, for each operating state, not the aggregate
449      discharges applied to the entire equipment. For example, a 10% entry means that the indicated
450      response is acceptable if it occurs on no more than 2 of the 20 discharges applied to each test
451      point.
452   5. It is desirable for equipment to comply with the performance criteria when direct discharges are
453      applied to internal areas that may be contacted during shipping, installation, maintenance,
454      adjustment, or repair.
455
456   4.4.5.4.    Method Of Test
457   4.4.5.4.1. Preparation
458   The test set-up for equipment is given in IEC 61000-4-2,
459   Prior to the application of the test discharges:
460   1. The CPE shall be configured with all necessary hardware and software and shall be operating in
461       accordance to its design specifications. Networked equipment shall be connected in a normal
462       network configuration.
463   2. Equipment interface connection points, including power leads, that provide a path for
464       electrostatic discharge currents during equipment operation shall be appropriately terminated 3.
465       For example, Tip and Ring shall be connected to a telephone network or a network simulator that
466       provides loop current, ringing, and DTMF detection.
467   3. The CPE shall be stabilized at laboratory conditions immediately before testing.
468




      3   Besides ESD currents carried on intentional paths to ground, the free space capacitance of auxiliary
            equipment may cause an interconnecting cable to carry significant ESD current even though the
            auxiliary equipment has no path to ground.

                                                       17
      PN-3-3283RV2                                  Draft 06                       (To be published as TIA-571-B)
                                                 TR41.7.4-05-11-002M
469   4.4.5.4.2. Test Modes
470   1. ESD Simulator Application: Type 1 and Type 2 ESD simulators shall be applied to equipment in
471       the manner and at the voltage levels given in the following table. If equipment is capable of
472       having different installation means, such as with and without a grounding conductor, each
473       possible installation means that can affect compliance shall be evaluated.
474
475                              Table 6 – ESD Discharge voltages and methods
                                                       Discharge voltage and method
                                Simulator           CONTACT (a)             AIR (b)
                                                    6 kV, direct and
                          Type 1 (IEC model)                           4 and 8 kV, direct
                                                        indirect
                           Type 2 (HBM) (c)          Not applicable           12 kV, direct
476      Conditions applicable to table:
477      A) Direct contact discharges are applied to conductive and static dissipative surfaces of the EUT
478          that have a discharge path to the grounding conductor. Ordinary paint is not considered to be
479          insulation and, therefore, painted metallic surfaces are subject to direct contact discharges.
480      B) Indirect contact discharges are applied to both the horizontal and vertical coupling planes.
481      C) Air discharges (sparking) are applied to insulating materials and to conductive and static
482          dissipative surfaces that are floating (ungrounded). Coatings, including paint, that are
483          designed to provide insulation are considered to render a metallic surface as insulated and,
484          therefore, coated metallic surfaces are subject to air discharges.
485      D) At the option of the manufacturer, a Type 1 (IEC model) simulator may be used.
486   2. Number of Discharges: At least 10 positive discharges and 10 negative discharges shall be
487      applied at each test point selected in accordance with 4.4.5.4.3. More than 10 discharges of each
488      polarity may be required to accommodate the various operating states of a sample (reference
489      “test Procedure section”)
490   3. Frequency of Discharges: Any charge remaining on the EUT shall be bled off after each
491      discharge via a high resistance to ground. Any effects on the equipment during the bleed-off are
492      disregarded. The time between successive discharges shall be at least 1 second.
493
494
495   4.4.5.4.3. Determination of Test Points
496   1. Areas on the equipment that are likely to be touched during normal operation shall be scanned to
497       determine their vulnerability to ESD. Examples of such areas include:
               equipment enclosures and their seams          dials and keypads              Switches
               sockets designed for metallic plugs           pushbuttons                    Displays
                 such as telephone jacks
                                                              front panels                   Lamps
               exposed metallic shells of cable plugs        circuit pack faceplates        Consoles
               and connectors
                                                              connecting cords               Handsets
               test plug receptacles
                                                              light emitting diodes          Headsets
               exposed structural frame areas
                                                              wrist strap jacks              speakers
498




                                                         18
      (To be published as TIA-571-B)                  Draft 06                             PN-3-3283RV2
                                               TR41.7.4-05-11-002M
499   2. Points that are found to be vulnerable to ESD during scanning shall be used as the test points. At
500      least four test points shall be established for direct discharges, which are in addition to the
501      indirect discharges to the vertical and horizontal coupling planes. Additional test points may be
502      chosen.
503   3. Circuit packs (as stand-alone assemblies), backplanes, and other intentionally exposed wiring
504      shall not be tested.
505   4. Scanning should be performed by setting the ESD simulator to continuous running (typically at
506      20 discharges per second) while discharging to possible test points. Scanning should be
507      conducted with an ESD simulator set at the specified test voltage. Multiple units may be scanned
508      to determine test points to prevent possible weakening of components or carbon tracking due to
509      ESD flashes during the scanning process. At the manufacturers option, when scanning insulated
510      surfaces for breakdown, the scan voltage may be reduced from the specified test voltage in
511      consideration of the altitude of the test facility4 by the following multipliers:
512                                 Table 7 – Test voltage vs. altitude multipliers
                                                 Altitude Multiplier
                        Sea level             500 m             1,000 m               2,000 m
                           1                   0.94               0.89                  0.79
513   4.4.5.4.4. Test Procedure
514   1. In general, both direct and indirect discharges are applied for all operating states of the
515       equipment. If discharges to an EUT while in a primary operating state (e.g., off-hook) are
516       sufficient to evaluate the ESD vulnerability of the EUT while in a secondary operating state (e.g.,
517       hold), only the primary state need be tested. However, if the sufficiency of such a procedure is
518       not known, then all operating states shall be tested.
519   2. A cordless telephone handset, while insulated from earth, is charged by applying direct contact
520       discharges to exposed metal such as the antenna or charging contacts. The handset is then
521       discharged to earth through the charging contacts by cradling the handset. This test method
522       (known as a charged body test) is applicable to similar hand-held battery powered equipment.
523   3. The bottom of equipment not normally carried during operation, and installed only by service
524       personnel, shall not be tested. If the equipment can be installed by users, the bottom shall be
525       tested using the Type 1 simulator.
526   4. If a test point exhibits ESD sensitivity in more than one operating state, the ESD sensitivity for
527       each operating state is to be evaluated by distributing the discharges over each operating state to
528       be tested, e.g. 5 discharges on-hook and 5 discharges off-hook. However, no less than 3
529       discharges (of each polarity) shall be applied per operating state so the total number of
530       discharges can exceed 10 of each polarity. For example, a test point could receive 3 discharges
531       each in an on-hook idle state, on-hook ringing state, off-hook idle state, and an off-hook hold
532       state, for a total of 12 discharges to the same test point.
533   5. Doors and panels are tested as follows:
534        if not required to be opened by the user, doors and panels shall remain closed during testing.
535        if required to be opened by the user (e.g., to access batteries), Type 1 discharges only shall be
536            applied to wrist strap jacks located behind the door or panel. If there are no wrist strap jacks,
537            parts behind the door or panel are treated as if the door or panel wasn’t present, and shall
538            only be subject to the Type 1 simulator.
539        if required to be opened by service personnel during operation;


      4   The correction is for the scanning voltage only, to determine if breakdown will occur at a given
            point on the equipment. The compliance test voltage is not adjusted for altitude. The correction is
            from IEC-950.

                                                        19
      PN-3-3283RV2                               Draft 06                    (To be published as TIA-571-B)
                                              TR41.7.4-05-11-002M
540              for doors and panels made of conductive materials and affixed to the equipment, direct
541               contact discharges shall be applied to edges and inner surfaces of a door or panel while it
542               is open.
543            for doors and panels either made of insulating materials, or not affixed to the equipment,
544               indirect contact discharges shall be applied to a vertical coupling plane while the door or
545               panel is open or removed from the equipment.
546   6. A test report, including the test points chosen, the test voltage, the operating states, the sequence
547      of testing, and the test results, shall be prepared.




                                                        20
      (To be published as TIA-571-B)             Draft 06                                 PN-3-3283RV2
                                            TR41.7.4-05-11-002M
548   ANNEX A (INFORMATIVE) – ELECTROMAGNETIC INTERFERENCE
549   A.1 RADIO FREQUENCY IMMUNITY (RFI)
550   The RF immunity test methods and performance criteria are contained in latest revision of TIA-631.
551
552   A.2 EMISSIONS
553   Limits for radiated emissions, and conducted emissions on ac power leads, are specified in the FCC
554   Part 15 Rules.
555




                                                    21
      PN-3-3283RV2                              Draft 06                    (To be published as TIA-571-B)
                                             TR41.7.4-05-11-002M
556   ANNEX B (INFORMATIVE) RATIONALE FOR TELEPHONE LINE OVERVOLTAGE
557           TESTS
558   B.1 SOURCES OF OVERVOLTAGE
559   1. Contact with multi-grounded neutral primary power line, 4 kV to about 150 kV.
560   2. Induction from primary power line fault current.
561   3. Ground potential rise from primary power line fault current flowing to ground.
562   4. Contact with secondary power line, 120 V.
563
564   B.2 ANALYSIS OF LIMITING OVERVOLTAGE CONDITIONS
565   Longitudinal voltage (L-type) of up to 600 V rms can occur on inside wiring that is protected with 3-
566   mil carbon blocks. Asymmetrical operation of the carbon blocks can result in metallic voltages (M-
567   type) of 200 to 600 V rms (60 Hz).
568   Five conditions of overvoltage apply to terminal equipment:
569   1. An I2t of 2400 can result from power line contact to a telephone shielded cable. A test condition
570       of 40 amperes for 1.5 seconds was chosen to give this I2t. I2t is directly related to heating in
571       adiabatic processes.
572   2. Up to 7 amperes for 5 seconds can result from induction or from a ground potential rise after a
573       power line fault to a multi-grounded neutral conductor.
574   3. Induced currents of up to 2.2 amperes, steady state, can result from a power line fault to resistive
575       earth, wherein the fault current is not sufficient to cause the power line breakers to trip.
576       Equipment must be evaluated over the range of possible currents.
577   4. Induced voltages may be low enough not to activate voltage limiting devices. Equipment must be
578       evaluated over the range of possible voltages.
579   5. A 120 volt power line crossed with a telephone line can deliver up to 25 amperes to the telephone
580       wiring, limited by the wiring impedance.
581   Maximum induction voltages occur when a telephone cable is run in joint use with power lines.
582   Certain digital systems (such as an ISDN S/T interface) impose system limitations that limit the cable
583   length to 1000 meters or less. With such a short range, induced voltages are limited to less than 60
584   volts and conditions 3 and 4 above are not considered.
585   Contact conditions can occur on any telephone cable that is run with power cables, including short
586   lines within a campus environment. Therefore, contact conditions 1, 2, and 5 above apply for all ex-
587   posed telephone cables.
588




                                                        22
      (To be published as TIA-571-B)                 Draft 06                                PN-3-3283RV2
                                               TR41.7.4-05-11-002M
589   B.3 PERFORMANCE OF TELECOMMUNICATIONS USER PREMISES EQUIPMENT
590   Traditional telephone equipment, which has proven safe in years of use for millions of installations,
591   is not hazardous when subjected to the above overvoltage conditions because of the following
592   equipment parameters:
593   1. The traditional telephone is the 500-type made of flammability class HB material. An
594       electromechanical 500-type set as manufactured in the 1970’s is damaged by a 2.2-A current, but
595       the damage is confined to a protective metal can inside the set. The telephone's speech network
596       has an impedance of 50 ohms above 1 A, and fuses open at I2t=40, thereby protecting the
597       telephone line cord by limiting fault current. The tip and ring conductors are also isolated from
598       ground so that longitudinal voltages cause no damage. Some telephone systems with grounding
599       conductors have used heat coils (a type of fuse) on the telephone lines to protect the building
600       wiring.
601   2. The traditional telephone line cord was made of phosphor bronze tinsel conductor. Tinsel cord
602       softens at 2.2 A (long duration), at 7 A for 5 seconds, and at I2t=400 for short durations, but the
603       conductors do not melt through the jacket at these current levels.
604   3. Modular jacks can withstand 2.5 A (long duration) and I2t=400 (short durations) before the jack
605       material (early model jacks) begins to melt. Leaded jacks use 26 AWG stranded wire for the
606       leads.
607   4. Riser cable (26 AWG min., solid wire, the smallest gauge in use for premises wiring) can
608       withstand 5 A (long duration) and I2t=1200 (short durations). At I2t=2400 the conductors will
609       melt their insulation but will not fuse open. A 26 AWG cable longer than about 100 feet is self
610       protecting due to current limiting provided by its wire resistance.
611   Modems built to computer industry standards have traditionally used fire resistant enclosure
612   materials to provide safety.
613
614   B.4 2-LINE AND 4-WIRE CIRCUITS
615   The overvoltage tests are applied to a representative pair of tip-ring leads for equipment that has
616   multiple lines. If currents are induced into multiple lines going into a piece of equipment, the
617   induced cur-rent in one pair produces an EMF that induces a reversed current in the other pairs.
618   Therefore, not all pairs will have the maximum current, and worse case condition is likely to be
619   testing one pair with the maximum current.
620   Digital circuits often use a 4-wire (F-type) circuit, one pair for transmit and another pair for receive.
621   A 4-wire circuit is not two 2-line circuits, e.g., the transmit and receive circuits are interconnected.
622   To test both circuits, a 4-wire test was designed to be used as a single test, instead of having several
623   tests on the various paths possible.
624
625   B.5 MULTIPLE SETS
626   The telephone line may be connected to several telephone stations (branches). Current in the main
627   line (unbranched) must be limited to I2t=400 to protect the line cord.
628   A common installation has a telephone set and an answering machine, each of which can terminate
629   the network in a low impedance after an overvoltage event. If each branch were fused for I2t=400,
630   the main line could see a much higher current. Assuming fault current is evenly distributed to the
631   branches, each branch (i.e., the telephone and answering machine) needs to limit short duration cur-
632   rent to I2t=400/22= 100.
633




                                                       23
      PN-3-3283RV2                               Draft 06                    (To be published as TIA-571-B)
                                              TR41.7.4-05-11-002M
634   B.6 WIRING SIMULATION
635   A composite model of a telephone line cord has a limiting l-t characteristic that is determined by the
636   following:
637   1. Long duration current limit is just over 2.2 A.
638   2. The current limit is just over 7 A at a 5-second duration.
639   3. Short duration (adiabatic) current-time characteristic is about I2t=100 .
640   Characteristics (1) and (2) are within the test parameters. To provide an indication of whether
641   telephone wiring would be damaged during a short duration fault a fuse that opens at I2t=100 is
642   desirable to use for testing purposes. If such a fuse is blown open during testing, the telephone line
643   cord would be damaged. A fuse that meets these parameters is the Bussman MDL-2.
644   It is not necessary to use a fuse; the wiring model could be used to evaluate test results obtained with
645   a current probe. Also, 32 AWG copper wire has a suitable fusing characteristic to be used as an
646   indicator.
647   Not all telephone line cords use tinsel wire. When 26 AWG stranded wire (the same wire gauge as
648   riser cable) is used, equipment does not need to limit I2t to 100 because the line cord is considered
649   sufficiently robust.
650
651   B.7 PRIMARY PROTECTOR COORDINATION
652   If telecommunications user premises equipment provides a low impedance path to ground (including
653   operation of arrestors that provide a path to ground during surges), a fault current could by-pass the
654   primary protector and result in excessive current through the telephone building wire and the
655   equipment. The building wire can provide coordination if it has enough resistance, which is not
656   always the case. The equipment’s characteristics should coordinate with the protector operation,
657   which is achieved by having a fusing limit of I2t=100.
658
659   B.8 TEST POINTS
660   To minimize testing effort, only the worst case test conditions need be evaluated. These usually
661   occur at maximum voltage and current except when voltage or current limiting devices (usually
662   MOVs and fuses, PTCs or fusible resistors) are used. Then, conditions of maximum voltage and
663   current that are not interrupted by limiting devices need be evaluated.
664




                                                        24
      (To be published as TIA-571-B)              Draft 06                                  PN-3-3283RV2
                                             TR41.7.4-05-11-002M
665   B.9 TEST CONDITIONS
666   1. Overvoltage conditions can be longitudinal or metallic. Both modes need be evaluated
667      independently when equipment has a grounding conductor.
668   2. The test conditions apply to both series and terminal equipment. For series equipment testing,
669      terminal equipment is simulated as both a short circuit and an open circuit in separate tests.
670   3. No testing is necessary in the following situations:
671      A) Longitudinal tests are not necessary if a dielectric barrier exists between tip-ring and ground.
672          Instead, a simpler dielectric test can be conducted.
673      B) For metallic tests, series equipment (note that a line cord can be thought of as series
674          equipment) needs to be tested only to M-2 and M-3 when the terminal equipment is
675          simulated as a short circuit because the terminal equipment provides protection for the M-1
676          test.
677      C) When current (and possibly voltage) limiting is provided by a secondary protector suitable
678          for the purpose, either:
679           The test conditions are adjusted so that they do not exceed the ratings of the protector, or
680           The equipment is tested with the protector in place.
681
682   B.10 FAILURE CONDITIONS
683   1. Fire hazards are evaluated using a cheesecloth indicator wrapped around the equipment under
684      test.
685   2. Shock hazards are evaluated with a leakage current test applied after testing. A simpler dielectric
686      test may be used.
687   3. Telephone line cord hazards are evaluated against the wiring model (using an indicator fuse, 32
688      AWG wire or current probe).




                                                     25
      PN-3-3283RV2                               Draft 06                    (To be published as TIA-571-B)
                                              TR41.7.4-05-11-002M
689   ANNEX C (INFORMATIVE) RATIONALE FOR SURGES
690   C.1 SOURCES OF SURGES
691   The most common source of surges on telephone tip-ring conductors results from a lightning strike to
692   an aerial or buried cable shield. The lightning current flowing on the shield to earth induces a
693   voltage into the cable pairs within the shield. If the ground path offers a high impedance to the
694   lightning cur-rent, the voltage along the shield may build up enough to produce a side flash to the
695   cable pairs within the shield, especially at wire junctions where the only insulation is air spacing. A
696   side flash can be considered a direct lightning strike to tip-ring that is mitigated by a parallel ground
697   path along the shield.
698   Another source of surges to equipment is via the power service to the building. Lightning surges
699   may enter a building over the serving power service conductors. Such lightning activity can also
700   result in a local ground potential rise with respect to remote earth, which can cause telephone
701   protectors to operate.
702
703   C.2 TRADITIONAL TELECOM SURGE SPECIFICATION
704   When the 500-type set was being designed, a field study of induced lightning surges was conducted
705   to provide design information for the insulation. Direct lightning surges were not studied. Surge
706   volt-ages were measured behind a primary protector (using 3-mil carbon blocks) and found to have a
707   peak value of 600 volts. The voltage waveshape (needed to determine the energy of the surge) had
708   an envelope of a 10 ms rise time to peak voltage, and a 1000 ms fall time to half of peak voltage
709   (referred to as a 10x1000 ms waveshape). The maximum induced voltage on the line side of the
710   primary protector was about 1000 volts. Therefore, a protector functions mainly to arrest voltages
711   from direct lightning hits and power crosses, which can be much higher than 1000 volts.
712   The peak induced current for cable runs is limited by cable impedance. The longer the cable run the
713   higher the induced voltage but the higher the wire resistance. This results in induction looking like a
714   constant current source of about 5 amperes but with a wide variation possible.
715   For metallic surges, current is limited by the impedance of the telephone terminating the line. The
716   traditional 500-type telephone has an impedance of 600 ohms at lightning frequencies, but surge cur-
717   rents saturate the hybrid voice transformer and cause its impedance to drop to the dc resistance of the
718   windings, about 40 ohms. If a 1000 volt surge with no cable impedance is applied to such a
719   telephone, the surge current would be 25 amperes.
720   For longitudinal surges applied to 500-type telephones, only insulation is stressed so that very little
721   current actually flows unless there is a breakdown. The voltage and current waveshapes are
722   identical.
723   To test 500-type telephones, the current should be limited by the equipment under test, not the surge
724   generator impedance. Having a surge generator capable of delivering 100 amperes satisfies that aim
725   and was a design parameter for the Bell System surge simulator. It was not based on field studies.
726




                                                         26
      (To be published as TIA-571-B)               Draft 06                                  PN-3-3283RV2
                                              TR41.7.4-05-11-002M
727   C.3   SURGE TYPES
728   C.3.1 L-type (Longitudinal)
729   Lightning surges induce voltages onto both tip and ring conductors. When a power line fault causes
730   arcing to cable pairs, the arcing usually occurs to both conductors. A ground potential rise has the
731   same effect as a line fault but in the reverse direction. All of these result in a longitudinal voltage,
732   which is a common mode voltage.
733   When several telephone line protectors are connected to the same protector ground, a discharge
734   through some protectors can cause a ground potential rise. For telephone lines whose protector is not
735   firing the ground potential rise adds to the voltage induced onto the telephone lines.
736
737
738   C.3.2 M-type (Metallic)
739   Metallic voltages (between tip and ring) are created when the primary protector grounds only one
740   conductor of the tip-ring pair. The longitudinal voltage on the other conductor then becomes a
741   metallic voltage, which is a differential mode voltage between tip and ring. A ground potential rise is
742   common to both tip and ring, so it does not affect the metallic voltage.
743
744   C.3.3 P- type (Power)
745   Power line surges commonly appear on a grounding conductor (causing a ground potential rise for
746   the telephone line as well as the power line) but the phase and neutral conductor can also be hit by
747   lightning between the power company transformer and the building being served. A high voltage on
748   the building’s grounding system can also arc over to phase and neutral, and the surge is then
749   transmitted through the power system as a common mode voltage.
750
751   C.3.4 T-type (Transverse)
752   Equipment with a 2-wire power cord usually has no ground reference but a P-type common mode
753   surge can appear on phase and neutral. The telephone line then becomes the ground reference for the
754   surge and arcing can occur between the power line and the telephone line. This is known as a
755   transverse surge. For equipment with a 3-wire power cord, transverse surges are still possible if the
756   insulation between phase/neutral and the grounding conductor is better than the insulation between
757   phase/neutral and the telephone line.
758
759   C.3.5 I-type (Intrabuilding)
760   An intrabuilding surge occurs when the steel structure of a building conducts a lightning discharge
761   which in turn induces a longitudinal voltage in telephone cables running parallel with the steel. This
762   is a source of longitudinal voltages for cables that do not connect to the outside plant.
763
764   C.4 OPEN CIRCUIT VOLTAGE AND VOLTAGE WAVESHAPE
765   Induction voltages are usually less than 1000 volts peak, but have elongated (10x1000 ms) wave-
766   shapes. Direct voltages are often 4000 volts or more, with short (1.2x50 ms) waveshapes.
767   Surges cause components to fail by different mechanisms, depending on the component’s weakness,
768   and one surge parameter cannot account for all failures. The voltage parameters are:
769    Peak voltage: The peak voltage can cause carbon tracking in insulation and is a common source
770       of breakdown. A peak voltage of 1000 V covers nearly all induced surge voltages.
771    Voltage heating: Leakage current through insulation can cause V2 dt heating of the insulation.
772       This is not considered significant for insulators but played a role in deriving the FCC surges.
773


                                                      27
      PN-3-3283RV2                              Draft 06                  (To be published as TIA-571-B)
                                             TR41.7.4-05-11-002M
774   C.5 SHORT CIRCUIT CURRENT AND CURRENT WAVESHAPE
775   Peak available current and current waveshape are very important for CPE that use voltage and cur-
776   rent limiting devices. In many older surge definitions the voltage waveshape and current waveshape
777   were considered the same since the surges were applied to insulation and only leakage current
778   resulted. In modern CPE, a surge protection element (like an MOV) becomes a low impedance
779   during a surge and significant surge current flows. The current waveshape under these conditions is
780   much shorter than the open circuit voltage waveshape, and 10x300 ms is a typical current waveshape.
781   The current parameters are:
782    Peak current: The peak current can cause heating of diode junctions that have a constant voltage
783       drop. This is usually insignificant.
784    Current heating: The V2 dt heating of resistance elements can cause operation of fuses used to
785       provide power line fault protection. This is a service affecting fault that should be avoided.
786
787   C.6   SURGE STUDIES AND DATA
788   C.6.1 Telephone line monitoring
789   The Bell System5 collected detailed lightning surge data at several locations in the 1970’s. The data
790   did not distinguish between induced and direct lightning surges. The I2t plot followed a normal
791   distribution with a maximum value of 0.6 A2-s, except for one surge that had an I2t of 1.2 A2-s.
792   Simultaneous voltage-current waveforms were also recorded, which showed that the events with the
793   maximum voltage and current had a voltage and current decay time of less than 300 ms, and tended
794   to be ringing waveforms (rather than simple exponential decays). While unipolar test waveshapes
795   cannot capture the variety of actual waveshapes, the energy content can be replicated.
796
797   C.6.2 Survey data
798   The Bell Labs studies were detailed records taken at a few sites. Other studies surveyed many sites
799   but with limited data. The two methods largely support each other. For example, in order to qualify
800   solid-state protectors (SSP) for Central Offices, BellSouth Services conducted a surge survey 6 that
801   showed a maximum energy of 0.55 A2-s. Since the telecom installations around Central Offices is
802   well controlled, it is likely that only induction surges were observed. The SSPs withstood these
803   induced surges.
804   GTE Telephone Operations conducted a survey at the station end of the telecom loop 7, where the
805   Bell System studies were made. Much higher energies were observed. Damaged SSPs were
806   sectioned and the energy required to accomplish the observed damage was estimated. Also, damage
807   from direct lightning was distinguished from damage from power cross (which was more severe).
808   The maximum surge energy was equivalent to a 500 A, 10x1000 ms waveform, which has an energy
809   of 175 A2-s. This is 3 orders of magnitude greater than the energy from induced surges.
810




      5 R. L. Carroll, “Loop transient measurements in Cleveland, South Carolina,” and other articles,
          BSTJ, November 1980.
      6 Mel Thrasher, “A solid-state solution,” Telephony, June 12, 1989.
      7 C. A. Francis II, W. J. McCoy, “The analysis of solid-state overvoltage protection at customer
          premises locations,” Compliance Engineering, May-June 1996.


                                                       28
      (To be published as TIA-571-B)               Draft 06                                   PN-3-3283RV2
                                              TR41.7.4-05-11-002M
811   C.7    STANDARDS ON SURGES
812   C.7.1 FCC Rules, Part 68
813   The 600 V, 10x1000 ms waveshape used in the Bell System was not judged to be adequate when the
814   FCC instituted a registration program for telephones. Industry wide, protector let-through voltages
815   were more like 800 V peak, and that was the voltage selected for the FCC surge. However, the
816   energy of the 600 V, 10x1000 ms surge as measured by V2 dt (=360), was kept constant for the 800
817   V surge by adjusting its waveshape to 10x560 ms (V2 dt =358).
818   For longitudinal voltages, a peak voltage of 1500 V was selected to represent a 1000 V surge and a
819   500 V ground potential rise. To maintain the same energy as used for metallic surges, the waveshape
820   was adjusted to 10x160 ms which gives V2 dt =360.
821   Like the Bell System surge, the surge generator was specified to provide 100 A to make sure the
822   generator did not limit the surge current, and no distinction was made between the open circuit
823   voltage and the short circuit current waveshapes.
824
825   C.7.2 CCITT Recommendation K.17
826   The CCITT established a surge circuit for telecom purposes in Recommendation K.17. The open
827   circuit voltage waveshape is about 10x700 ms, while the short circuit current is about 10x310 ms, in
828   good agreement with field surveys. By specifying a surge circuit, a linear response is guaranteed for
829   any load impedance. The FCC surge specifies only open circuit and short circuit waveshapes, and
830   permits undesirable non-linear responses for loads other than at the specification points.
831   The surge voltage is not specified in K.17, since that is dependent on the installation. A value of
832   1000 volts metallic and 1500 volts longitudinal is appropriate. The output impedance of the CCITT
833   circuit is high, 40 ohms, which limits available current at 1000 volts to 25 A. This results in an I2t of
834   0.136 A2-s for the metallic surge, which represents about 98% of all surges but is low compared to
835   the maximum values seen in the surveys.
836   The energy from the longitudinal surge through each conductor should be the same as for a metallic
837   surge, since a metallic surge is a longitudinal surge with one conductor earthed. This is
838   accomplished for the level A surge with the CCITT generator. For level B surges, the power line
839   generator is a better model for achieving the energy desired.
840
841   C.7.3 ANSI/IEEE C62.45
842   IEEE 587 (adopted as ANSI C62.45 with some updates) established a surge for power lines that has
843   an open circuit voltage waveshape of 1.2x50 ms, a short circuit current waveshape of 8x20 ms, and
844   an output impedance of 2 ohms. This is typical of direct lightning surges. The peak voltage is
845   specified as 6 kV for location category B, limited by the arc over characteristic of power receptacles.
846
847   C.7.4 IEC 61000-4-5
848   This IEC surge standard has two circuits, the CCITT circuit for telephone line surges and the ANSI
849   waveshapes for power line surges (giving a schematic but without values). The CCITT circuit with
850   the 25  resistor bypassed is also shown. Thus, the CCITT and ANSI circuits have become the
851   worldwide norms for surges. The standard gives severity levels for the power line surge of 1, 2, and
852   4 kV, de-pendent on the building installation category.
853   The open circuit voltage is specified at the output terminals of the surge circuit. Some standards
854   specify the voltage the capacitor is charged to. To achieve 5000 volts at the output terminals, the
855   capacitor must be charged to 6000 volts because of the voltage divider in the output.
856




                                                       29
      PN-3-3283RV2                              Draft 06                   (To be published as TIA-571-B)
                                             TR41.7.4-05-11-002M
857   C.8   SURGE LIKELIHOOD
858   C.8.1 Level A and level B
859   Induced surges are described as level A or level B. Level A does not mean average, but that level of
860   stress that equipment must withstand to have a reasonable life. Level B surges represent the
861   envelope of surge energies that equipment also needs to withstand. However, the equipment sees
862   many more level A surges than level B surges.
863
864   C.8.2 Level C
865   Terminal equipment is normally protected against direct lightning strikes by protectors, but
866   occasional poor grounding is unavoidable. Therefore, it is desirable for terminal equipment to
867   withstand direct strikes, and must at least be safe under such conditions. The level C lightning
868   condition is taken from the Bellcore generic requirement GR-1089.
869
870   C.9   SURGES FOR TELECOMMUNICATIONS EQUIPMENT
871   C.9.1 Metallic
872   Surge M-1 uses the CCITT generator. With the 25  resistor at 1000 volts, the I2t is 0.136. Surge M-
873   2 uses the FCC 800 V, 10x560 µs generator which produces an I2t of 4. The M-3 surge uses the GR-
874   1089 1000 V, 10x1000 µs generator which produces an I2t of 7.
875
876   @@@ Rational: These changes are required to make this section correspond with the changed
877   requirements in SP 3283-A-2.
878
879   C.9.2 Longitudinal
880   The level A longitudinal surge uses the CCITT generator at 1500 volts, with an I2t of 0.129 for each
881   leg. The level B longitudinal surge actually represents a ground surge and has an I2t of 1.01 for each
882   leg. The level C surge has an I2t of 7 for each leg.
883
884   C.9.3 Power
885   The power line surges use the IEEE waveshape and an exposure likelihood based on IEC 1000-4-5.
886   That is, surges on phase and neutral rarely exceed 2500 volts, the value used for the FCC power line
887   surge. Ground surges are more likely to reach 5000 volts, the value used in TIA-571. The I2t at
888   2500 volts is 17.5, and at 5000 volts is 70.
889
890   C.9.4 Transverse
891   A transverse surge occurs between phase/neutral and tip/ring (acting as the ground path). Because
892   the telephone line has more resistance than the power line, an additional 3 ohms is added to each tip
893   and ring lead based on field experience. The I2t at 2500 volts is 2.8, and at 5000 volts is 11.2.
894
895   C.9.5 Ground
896   A ground surge is the same as a power line surge on the grounding conductor.
897




                                                       30
      (To be published as TIA-571-B)              Draft 06                                 PN-3-3283RV2
                                             TR41.7.4-05-11-002M
898   ANNEX D (INFORMATIVE) - GROUNDING PRACTICES
899   The following telecommunication equipment grounding practice is frequently used:
900   1. All circuit commons within the equipment enclosure are derived from a single ground
901      concentration point within the cabinet. Each cabinet's ground concentration point derives ground
902      from a single ground concentration point serving all system cabinets and peripherals collocated
903      with the system.
904   2. The system cabinets and all associated ducting hardware along with all collocated peripherals are
905      not connected to any ground source other than the system single-point ground, de-scribed in (1).
906   3. Service wires bringing commercial power to the cabinets do not share an enclosure or raceway
907      with any other system grounds, dc power distribution wires, or signaling wires. Commercial
908      power terminations not made by means of a connector are enclosed by race-ways and termination
909      boxes, whether these enclosures appear outside or within system cabinets. This is to ensure that
910      ac service wires cannot fault to circuitry within system cabinets or associated ducting hardware.
911   4. All system hardware are provided with an ac fault return path to the system single-point ground
912      which, in turn, is provided with a reliable path to the equipment’s grounding conductor. The
913      path from system equipment to single-point ground need not be a direct, dedicated path but can
914      be any reliable path to other system hardware which receives the above grounding path.
915   5. All sources of earthing (i.e., system signaling ground to the approved ground source etc.) connect
916      only to the system single-point ground. The intent of providing for a system single point ground
917      is to minimize ground loops and prevent lightning from finding a path through system
918      components.
919   Other techniques that achieve equivalent results are also used.
920




                                                     31
      PN-3-3283RV2                              Draft 06                   (To be published as TIA-571-B)
                                             TR41.7.4-05-11-002M
921   ANNEX E (INFORMATIVE) - TELEPHONE LINE VOLTAGES AND CURRENTS
922   CPE in the on-hook or the off-hook state can encounter voltages and currents at the network interface
923   as described in ANSI/T1.401. .
924




                                                       32
      (To be published as TIA-571-B)               Draft 06                                  PN-3-3283RV2
                                              TR41.7.4-05-11-002M
925   ANNEX F (INFORMATIVE) - STEADY STATE POWER INDUCTION
926   Induction resulting from magnetic fields surrounding power distribution systems can result in
927   longitudinal voltages appearing on tip and ring conductors with respect to earth. Since the induced
928   voltage is in series with, and generally distributed along the loop or metallic facility involved, the
929   longitudinal mode voltage will be a function of the far-end termination of the loop, as well as the
930   loop characteristics. These voltages are usually low, although there is a small probability of being 50
931   volts rms or greater when the terminal equipment has a high longitudinal impedance and the central
932   office end has a low longitudinal impedance.
933   The induced current at a telephone interface connecting to terminal equipment possessing a low
934   longitudinal impedance usually does not exceed 100 mA rms (50 mA rms per conductor) when a low
935   longitudinal impedance is present at the central office end.
936   Longitudinal voltages may be converted to metallic voltages because of system impedance
937   imbalances, but the metallic voltages usually do not exceed 24.5 mV rms (60 dBrn with 3 kHz flat
938   weighting).
939   Susceptibility of equipment to longitudinal voltage signals is addressed by the longitudinal balance
940   requirements in TIA-470.210-C.
941




                                                      33

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:2
posted:11/25/2011
language:English
pages:41