Docstoc

Specification for a single-phase pad-mounted distribution transformer

Document Sample
Specification for a single-phase pad-mounted distribution transformer Powered By Docstoc
					Specification for a Single-Phase Pad-Mounted Distribution Transformer 10 - 167 kVA
Ref.: Cooper Power Systems catalog section 201-20

[Note to Specifier: The following specification incorporates the standard features of the Cooper Power Systems' single-phase pad-mounted distribution transformer. The price adders for the accessories in section 7 are available at time of quote or from your Cooper Power Systems' representative.] 1.0 1.1 GENERAL This specification covers the electrical and mechanical characteristics of Single-Phase Pad-Mounted Distribution Transformers. All characteristics, definitions, and terminology, except as specifically covered in this specification, shall be in accordance with the latest revision of the following ANSI and NEMA standards. C57.12.00 - IEEE Standard General Requirements for Liquid-Immersed Distribution, Power and Regulating Transformers. C57.12.25 - Pad-Mounted, Compartmental-Type, Self-Cooled, Single-Phase Distribution Transformers With Separable Insulated High-Voltage Connectors; High Voltage, 34500GRDY/19920 Volts and Below; Low Voltage, 240/120 Volts; 167 kVA and Smaller-Requirements. C57.12.28 - Pad-Mounted Equipment - Enclosure Integrity. C57.12.35 - Bar Coding for Distribution Transformers C57.12.90 - IEEE Standard Test Code for Liquid-Immersed Distribution, Power, and Regulating Transformers and IEEE Guide for Short-Circuit Testing of Distribution and Power Transformers. C57.12.91 - Guide for Loading Mineral-Oil-Immersed Overhead and Pad-Mounted Transformers Rated 500 kVA and Less with 65C or 55C Average Winding Rise. 2.0 2.1 RATINGS The transformer shall be designed in accordance with this specification and shall have one of the following kVA ratings: 10, 15, 25, 37.5, 50, 75, 100, 167

1.2

Rev. 2/15/00

The applicable kVA rating shall be specified on the inquiry. Table 1 Transformer and Connector High-Voltage Ratings and Electrical Characteristics
Electrical Characteristics of the Completely Assembled High-Voltage Connectors1) Transformer High-Voltage Rating2) High-Voltage Ratings (volts) Single High-Voltage 4160GrdY/2400 8320GrdY/4800 12000GrdY/6930 12470GrdY/7200 13200GrdY/7620 13800GrdY/7970 16340GrdY/9430 22860GrdY/13200 23900GrdY/13800 24940GrdY/14400 34500GrdY/19920 Series - Multiple High-Voltage 4160GrdY/2400 x 12470GrdY/7200 4160Grdy/2400 x 13200GrdY/7600 8320GrdY/4800 x 24940GrdY/14400 12470GrdY/7200 x 24940GrdY/14400 13200GrdY/7620 x 24940GrdY/14400 1) 2) 3) 4) Minimum BIL3) (kV) Phase-toGround (kV) 8.3 8.3 8.3 8.3 8.3 8.3 (8.3 or 15.2)4) 15.2 15.2 15.2 21.1 Phase-to-Ground /Phase-to-Phase (kV) 8.3/14.4 8.3/14.4 8.3/14.4 8.3/14.4 8.3/14.4 8.3/14.4 (8.3/14.4 or 15.2/26.3)4) 15.2/26.3 15.2/26.3 15.2/26.3 21.1/36.6 95 95 95 95 95 95 (95 or 125)4) 125 125 125 150 34 34 34 34 34 34 (34 or 40)4) 40 40 40 50 BIL (kV) 60-Hz dry one minute withstand (kV)

60 75 95 95 95 95 95 125 125 125 150

60 x 95 60 x 95 75 x 125 95 x 125 95 x 125

8.3 8.3 15.2 15.2 15.2

8.3/14.4 8.3/14.4 15.2/26.3 15.2/26.3 15.2/26.3

95 95 125 125 125

34 34 40 40 40

For complete connector rating, see ANSI/IEEE 386. Transformers are suitable for connectors with phase-to-ground or phase-to-ground/phase-tophase high-voltage ratings as listed. Arrester coordination may require higher BIL on multiple connection than indicated to achieve a minimum protection level of 20%. The required connector rating is to be specified.

2.2

The applicable voltage rating and BIL shall be specified on the inquiry.

Rev. 2/15/00

Dual voltage primaries shall utilize an externally operable switch. Unit must be deenergized prior to changing voltages. The BIL level for dual voltage units will correspond to each connection. The applicable multiple voltage rating shall be specified on the inquiry. 2.3 The secondary voltage shall be one of the following. The basic insulation level (BIL) of the secondary voltage shall be 30 kV. 240/120 480/240 277 120/240 (4 bushings) The applicable secondary voltage shall be specified on the inquiry. 2.4 The transformer may be furnished with full capacity high-voltage taps. The tap changer shall be clearly labeled to reflect that the transformer must be de-energized before operating the tap changer as required in Section 3.2.1 of ANSI C57.12.25. The unit shall have one of the following tap configurations: No taps Two - 2½% taps above and below rated voltage Four - 2½% taps below rated voltage NEMA taps (14400, 13800, 13200, 12470, 12540) The applicable tap configuration shall be specified on the inquiry. 3.0 3.1 HIGH VOLTAGE BUSHINGS AND TERMINALS The high voltage bushings provided shall be externally clamped Zytel  HTN bushing wells. These wells shall be removable to allow for field replacement of the bushings without opening the tank. The bushing configuration shall be per ANSI Figure 1A (15 & 25 kV Class) and 1B (35 kV Class) (for ANSI Type I units) or per Figure 2A (15 & 25 kV Class) and 2B (35 kV Class) (for ANSI Type II units). The applicable bushing configuration shall be specified on the inquiry. 3.3 A cable accessory parking stand shall be provided and shall be located such that the separable insulated connectors that are designed for operation after the transformer is in place can be operated with hot-line tools. LOW VOLTAGE BUSHINGS AND TERMINALS

3.2

4.0

Rev. 2/15/00

4.1

The configuration of the secondary shall be per ANSI C57.12.25 Figure 1A (This specifies a horizontal bushing arrangement or ANSI Type I unit) or Figure 2A (This specifies an angled bushing pattern or ANSI Type II unit). These bushings shall be removable to allow for field replacement without opening the tank. The transformer shall have threaded stud-type line and neutral terminals per Table 2 for ANSI Type II units. The transformer shall have 4-hole H-spade line and neutral terminals for ANSI Type I units. Table 2 Stud-type line and neutral terminals for ANSI Type II units kVA Rating 25-75 100-167 * Thread Size * 0.625-11 UNC-2A 1.000-14 UNC 2S Minimum Length * in 1.25 1.75 mm 31.9 44.5

4.2

Larger thread size or length, or both, may be required if materials other than copper are used.

4.3 5.0 5.1

The low voltage neutral shall be a fully insulated bushing with a removable ground strap. PROTECTION The protection scheme provided with the transformer shall consist of the following checked attributes. If for any reason a special protection scheme is required it shall be clearly stated on the inquiry. Note: The standard product typically has shorter leadtimes. [] Standard The transformer primary shall include a loadbreak Bay-O-Net assembly with a flapper valve to minimize oil spillage. The Bay-O-Net assembly shall be used in series with an internally mounted isolation link. Standard Overcurrent protection shall be provided by a dual sensing Bay-ONet expulsion fuse. Protected Overcurrent protection shall be provided by a dual sensing Bay-ONet expulsion fuse mounted in series with a partial range under-oil currentlimiting fuse such that the maximum interrupting rating is 50,000 A. This fusing scheme eliminates the requirement for the isolation link mounted in series with the Bay-O-Net assembly. Protected Plus Primary overvoltage protection shall be provided by an internally mounted, Heavy-Duty Distribution Class MOV surge arrester.

[]

[]

[]

Rev. 2/15/00

[]

Protected Plus Secondary overvoltage protection shall be provided by an externally mounted, high-energy, ANSI approved Light Duty Distribution Class surge arrester. Protected Plus (Magnex) Primary and Secondary overcurrent and transformer overload protection shall be provided by a breaker installed on the primary side of the transformer. This breaker shall have the capability to energize and deenergize the transformer by one hotstick operation. This device may be used in series with a current-limiting fuse to provide 50,000 A interrupting capability. Protected Plus Secondary overcurrent and transformer overload protection shall be provided by a breaker installed on the secondary side of the transformer. This breaker shall have the capability to energize and de-energize the transformer by one hotstick operation. This device shall be used in conjunction with an expulsion fuse on the primary side of the transformer. VFI Protected The transformer primary shall include a Vacuum Fault Interrupter. The VFI shall have a maximum interrupting rating of 12000A RMS with resettable fault protection up through 25kV. The VFI shall also include a Tri-Phase electronic breaker control with over 100 minimum trip settings and 5 selectable time current curves. The trip settings and curve shall be clearly stated on the inquiry in the format shown below. Trip Setting _______A Time-Current Curve: [ ] EF

[]

[]

[]

[ ] TF

[ ] KF

[]F

[]H

6.0 6.1

TANK AND TERMINAL COMPARTMENT In addition to the regular locking provision, all access doors or hood shall be secured by a recessed, captive, pentahead bolt that meets the dimensions set forth in RUS Drawing A3759. The transformer shall be of sealed tank construction of sufficient strength to withstand a pressure of 7 psig without permanent distortion, and 15 psig without rupturing or affecting cabinet security. The tank shall include a pressure relief device as a means to relieve pressure in excess of pressure resulting from normal operation. The venting and sealing characteristics shall be as follows: Cracking Pressure: 10 psig ± 2 psig Resealing Pressure: 6 psig minimum

6.2

6.3

Rev. 2/15/00

Zero leakage from reseal pressure to -8 psig Flow at 15 psig: 35 SCFM minimum 6.4 The tank coating shall meet all requirements in ANSI C57.12.28 including: Salt Spray Test Crosshatch Adhesion Test Humidity Test Impact Test Oil Resistance Test Ultraviolet Accelerated Weathering Test Abrasion Resistance - Taber Abraser 6.5 The pad-mounted equipment shall meet the requirements for tamper resistance set forth in ANSI C57.12.28 including the pry test, pull test, and wire probe test. The tank shall be complete with an anodized aluminum laser engraved nameplate. This nameplate shall meet ANSI Standard C57.12.00 for Nameplate A. The following section makes the product non-standard. The standard product typically has shorter leadtimes. 7.0 7.1 ACCESSORIES The following checked accessories shall be provided: [] [] [] [] [] [] [] [] [] [] [] [] Stainless Steel Hardware Service Entrance (2.25 inch) in the Sill Ground Connector Drain Valve / Sampling Device One-Piece Loadbreak Bushings Bushing Wells with Removable Studs High-Voltage Bushing Inserts R-Temp Less-flammable Fluid Envirotemp FR3 Less-flammable Fluid Loadbreak Switch Bay-O-Net Drip Shield Poly-pad - Combination shipping and mounting pad

6.6

Any additional accessories will be specified on the inquiry. 8.0 8.1 9.0 SHIPPING The unit shall be banded, blocked, or bolted to a suitable wood pallet or poly-pad. TESTING

Rev. 2/15/00

9.1

All units are subject to routine tests as prescribed in ANSI C57.12.00 In addition, impedance voltage and load loss tests are considered to be routine. The manufacturer shall provide the guaranteed average no-load and load losses for the unit at 85C. These losses will be subject to the tolerance specified in Table 3. Table 3 Tolerances for Single-Phase and Three-Phase Transformer Losses
Number of Units on One Order 1 2 or more 2 or more Basis of Determination 1 unit Each Unit Average of all units No-Load Losses (%) 10 10 0 Total Losses (%) 6 6 0

9.2

9.3

When a total owning cost evaluation is used, the economic factors for no-load and load losses used in the analysis shall be provided on the inquiry. BAR CODING A temporary bar code label shall be attached to the exterior of the transformer. accordance with ANSI C57.12.35.

10.0 10.1

Rev. 2/15/00


				
DOCUMENT INFO
Shared By:
Categories:
Stats:
views:79
posted:1/23/2010
language:English
pages:7
pptfiles pptfiles
About