ANSI C57.12.20-1997.pdf

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ANSI C57.12.20-1997

AMERICAN NATIONAL STANDARD

for Transformers—

Standard For Overhead Type Distribution Transformers,

500 kVA and Smaller:

High Voltage, 34500 Volts and Below;

Low Voltage, 7970/13800Y Volts and Below

Secretariat Secretariat

National Electrical Manufacturers Association

Approved May 3, 1997

American National Standards Institute, Inc.

Published by Published by

No part of this publication may be

No part of this publication may be reproduced in any form, in an reproduced in any form, in an electronic retrieval system or otherwise, without priorelectronic retrieval system or otherwise, without prior written permission of the

written permission of the publisher.publisher. Printed in the United States of

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American National Standard

Approval of an American National Standard requires verification by ANSI that the requirements for due process, Approval of an American National Standard requires verification by ANSI that the requirements for due process, consensus, and other criteria for approval have been met by the standards developer.

consensus, and other criteria for approval have been met by the standards developer.

Consensus is established when, in the judgment of the ANSI Board of Standards Review, substantial agreement has Consensus is established when, in the judgment of the ANSI Board of Standards Review, substantial agreement has been reached by directly and materially affected interests. Substantial agreement means much more than a simple been reached by directly and materially affected interests. Substantial agreement means much more than a simple majority, but not necessarily unanimity. Consensus requires that all views and objections be considered, and that a majority, but not necessarily unanimity. Consensus requires that all views and objections be considered, and that a concerted effort be made toward their

concerted effort be made toward their resolution.resolution.

The use of American National Standards is completely voluntary; their existence does not in any respect preclude The use of American National Standards is completely voluntary; their existence does not in any respect preclude anyone, whether he has approved the standards or not,

anyone, whether he has approved the standards or not, from manufacturing, marketinfrom manufacturing, marketing, purchasing, or using products,g, purchasing, or using products, processes, or procedures not conforming to the standards.

processes, or procedures not conforming to the standards.

The American National Standards Institute does not develop standards and will in no circumstances give an The American National Standards Institute does not develop standards and will in no circumstances give an interpretation of any American National Standard. Moreover, no person shall have the right or authority to issue an interpretation of any American National Standard. Moreover, no person shall have the right or authority to issue an interpretation of an American National Standard in the

interpretation of an American National Standard in the name of the American National name of the American National Standards Institute. RequestsStandards Institute. Requests for interpretations shall be addressed to the secretariat or sponsor whose name appears on the title page of this for interpretations shall be addressed to the secretariat or sponsor whose name appears on the title page of this standard.

standard.

CAUTION NOTICE:

CAUTION NOTICE: This American National Standard may be revised or withdrawn at This American National Standard may be revised or withdrawn at any time. The procedures of any time. The procedures of the American National Standards Institute require that action be taken to reaffirm, revise, or withdraw this standard no the American National Standards Institute require that action be taken to reaffirm, revise, or withdraw this standard no later than five years from the date of approval. Purchasers of American National Standards may receive current later than five years from the date of approval. Purchasers of American National Standards may receive current information on all standards by calling or writing the American National Standards Institute.

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Foreword

(This Foreword is not part of American National Standard C57.12.20-1997)(This Foreword is not part of American National Standard C57.12.20-1997)

In 1938

In 1938 the EEI-NEMA (Edison the EEI-NEMA (Edison Electric Institute-National Electrical ManufactureElectric Institute-National Electrical Manufacturers Association) Joint Committee onrs Association) Joint Committee on Standards for Distribution Transformers was organized to develop standards for the various types of distribution Standards for Distribution Transformers was organized to develop standards for the various types of distribution transformers. For 23 years the continuous work of this Joint Committee was evidenced by a series of reports published transformers. For 23 years the continuous work of this Joint Committee was evidenced by a series of reports published jointly by

jointly by the Edison the Edison Electric InstElectric Institute (EEI) itute (EEI) and the Natand the National Electrional Electrical Manufactical Manufacturers Associaturers Association (NEMA). Tion (NEMA). The lasthe last report on overhead-type distribution transformers was the Seventh Report published in April 1961. The Joint report on overhead-type distribution transformers was the Seventh Report published in April 1961. The Joint Committee’s last two reports on overhead-type distribution transformers were approved as American National Committee’s last two reports on overhead-type distribution transformers were approved as American National Standards, the Seventh Report being reissued as American National Standard C57.12.201938-1962.

Standards, the Seventh Report being reissued as American National Standard C57.12.201938-1962. To avoid further duplication of effort and

To avoid further duplication of effort and to simplify future revisions, the EEI-NEMA Joint Committee on Standardsto simplify future revisions, the EEI-NEMA Joint Committee on Standards for Distribution Transformers was dissolved and replaced by

for Distribution Transformers was dissolved and replaced by new subcommittees of Accredited Standards Committeenew subcommittees of Accredited Standards Committee on Transformers, Regulators, and Reactors, C57. The work on standards for overhead-type distribution transformers on Transformers, Regulators, and Reactors, C57. The work on standards for overhead-type distribution transformers was taken over

was taken over by the Subcommittee on Distribution Transformers, Overhead and Pad-Mounted, C57.12.2.by the Subcommittee on Distribution Transformers, Overhead and Pad-Mounted, C57.12.2. This standard was prepared by IEEE Subcommittee C57.12.2 on behalf of C57 and is

This standard was prepared by IEEE Subcommittee C57.12.2 on behalf of C57 and is a revision of ANSI C57.12.20-a revision of ANSI C57.12.20-1988, Requirements for Overhead-Type Distribution Transformers, 500 kVA and Smaller: High-Voltage, 67000 Volts 1988, Requirements for Overhead-Type Distribution Transformers, 500 kVA and Smaller: High-Voltage, 67000 Volts and Below; Low-Voltage, 15000 Volts and Below. The previous edition was dated 1981. The 1981 revision included and Below; Low-Voltage, 15000 Volts and Below. The previous edition was dated 1981. The 1981 revision included detailed requirements on relief of excessive pressure. The 1988

detailed requirements on relief of excessive pressure. The 1988 revision recognized the step-down and series-multiplerevision recognized the step-down and series-multiple designs in distribution transformers, and omitted the platform- or station-type transformer. In recognition of the designs in distribution transformers, and omitted the platform- or station-type transformer. In recognition of the dramatic reduction in catastrophic failures of overhead transformers since the formulation of NEMA Standards dramatic reduction in catastrophic failures of overhead transformers since the formulation of NEMA Standards Proposal Number TR-P7-1975, the 1988 revision included in Section 8. this updated NEMA proposal that is now Proposal Number TR-P7-1975, the 1988 revision included in Section 8. this updated NEMA proposal that is now designated 2.02 of NEMA Standards Publication for Transformers, Regulators, and Reactors, NEMA

designated 2.02 of NEMA Standards Publication for Transformers, Regulators, and Reactors, NEMA TR 1-1980. TheTR 1-1980. The general industry consensus is that transformers that are built in conformance with this standard and

general industry consensus is that transformers that are built in conformance with this standard and that have adequatethat have adequate overcurrent protection, and recognizing the limitations included therein, will provide for enclosures with reasonable overcurrent protection, and recognizing the limitations included therein, will provide for enclosures with reasonable withstand capability.

withstand capability.

Suggestions for improvement of this standard will be welcome. They should be sent to the National Electrical Suggestions for improvement of this standard will be welcome. They should be sent to the National Electrical Manufacturers Association, 1300 North 17th

Manufacturers Association, 1300 North 17th Street, Suite 1847, Street, Suite 1847, Rosslyn, VirginiRosslyn, Virginia, 22209a, 22209

This standard was processed and approved for submittal to ANSI by Accredited Standards Committee on This standard was processed and approved for submittal to ANSI by Accredited Standards Committee on Transformers, Regulator

Transformers, Regulators, and Reactors, C57. s, and Reactors, C57. Committee approval of the standard does not necessarily imply that allCommittee approval of the standard does not necessarily imply that all committee members voted for its approval.

committee members voted for its approval. At the time it approved this standard, the

At the time it approved this standard, the C57 Committee had the following members:C57 Committee had the following members: Paul Orehek,

Paul Orehek, (Chairman)(Chairman) J. D. Borst,

J. D. Borst, (Vice Chairman)(Vice Chairman) John A. Gauthier,

John A. Gauthier, (Secretary)(Secretary) Organization Represented

Organization Represented ... Name of Representative Name of Representative U.S. Dept. of Energy,

U.S. Dept. of Energy, Western

Western Area Area Power APower Administradministrationtion ... ... ... ... ... Kenneth Kenneth C. WoC. Wolohonlohon Dept of Navy Civil Engineer Corps.

Dept of Navy Civil Engineer Corps. Civil

Civil Engineer Engineer CorpsCorps ... ... ... ... ... ... C.M. C.M. MandevilleMandeville Dept of Interior, Bureau of Reclamation...D. J. Mulligan Dept of Interior, Bureau of Reclamation...D. J. Mulligan Dept

Dept of of Agriculture, Agriculture, REAREA ... ... ... ... ... ... J. J. Bohlk Bohlk Tennessee Valley Authority...F. Lewis Tennessee Valley Authority...F. Lewis Electric Light & Power Delegatio

Electric Light & Power Delegationn Public

Public Service Service Electric Electric & & Gas Gas Co.Co. ... ... ... ... ... PP.E. Oreh.E. Orehek ek (Chairman of Delegation)(Chairman of Delegation) Consolidated

Consolidated Edison Edison Co. Co. of of NYNY, Inc, Inc. . ... ... ... ... .. E. A. E. A. BertoliniBertolini Niagara

Niagara Mohawk Mohawk Power Power Corp. Corp. ... ... ... ... ... T. T. DiamantisDiamantis T.U.

T.U. Electric Electric ... ... ... ... ... ... ... K. K. S. S. HanusHanus Edison

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Southern

Southern California California Edison Edison Co. ...Co. ... ... ... ... ... G. A. G. A. PaivaPaiva Tampa

Tampa Electric Electric Co. ...Co. ... ... ... ... ... ... ... J. J. SullivanSullivan Institute of Electrical & Electronic Engineers

Institute of Electrical & Electronic Engineers Delegation

Delegation

ABB Power T& D Company ...J. D. Borst

ABB Power T& D Company ...J. D. Borst(Chairman of Delegation)(Chairman of Delegation) Penn

Penn Power ...Power ... ... ... ... ... ... .... WW. . B. B. BinderBinder Beckwith Electric Company ...J. H. Harlow Beckwith Electric Company ...J. H. Harlow Baltimore

Baltimore Gas & Gas & Electric Electric Company ...Company ... ... ... ... ... J. WJ. W. Matthe. Matthewsws Southern

Southern Company Company Services Services Inc. Inc. ... ... ... ... ... B. B. PatelPatel PEMCO

PEMCO CorporationCorporation... ... ... ... ... ... H. H. SmithSmith(Alternate)(Alternate) Commonwealth

Commonwealth Edison .Edison ... ... ... ... ... ... T. T. P. P. TrauTraubb National Electrical Manufacturers

National Electrical Manufacturers Association Delegation

Association Delegation General

General Electric Electric Company ...Company ... ... ... ... ... ... G. G. CoulterCoulter(Chairman of Delegation)(Chairman of Delegation) Cooper Power Systems ...M. Austin

Cooper Power Systems ...M. Austin R.

R. E. E. Uptegraff Uptegraff ManufacturinManufacturing g Co.Co. ... ... ... ... ... S. S. EndersbeEndersbe Cooper Power Systems...A. Ghafourian

Cooper Power Systems...A. Ghafourian(Alternate)(Alternate) Square D Company...P.J. Hopkinson

Square D Company...P.J. Hopkinson ABB Power T&D Company...K. R. Linsley ABB Power T&D Company...K. R. Linsley ABB

ABB Power Power T&D T&D Company Company ... ... ... ... ... .... R. R. PlasterPlaster(Alternate)(Alternate) North

North American American TransformeTransformer, r, Inc. ...Inc. ... ... ... ... H. H. RobinRobin Hevi-Duty Electric ...J. Sims

Hevi-Duty Electric ...J. Sims(Alternate)(Alternate) Underwriters

Underwriters Laboratories, Laboratories, Inc. ...Inc. ... ... ... ... ... M. M. SchackerSchacker Members of Working Group C57.12.20

Members of Working Group C57.12.20 Glenn Andersen Glenn Andersen Rick Anderson Rick Anderson Jerry Bishop Jerry Bishop Charles V. Brown Charles V. Brown Ned Brush Ned Brush Charles Bryant Charles Bryant William E. Carter William E. Carter Tom Diamantis Tom Diamantis Kevin Edwards Kevin Edwards Ali Ghafourian Ali Ghafourian Ken Hanus Ken Hanus David Helriegel David Helriegel Richad Hollingsworth Richad Hollingsworth John Hunt John Hunt Ron Jordan Ron Jordan Brian Klaponski Brian Klaponski John Lazar John Lazar James Long James Long Mark Loveless Mark Loveless Dave Lyon Dave Lyon Al McGuire Al McGuire Matthew Mingoia Matthew Mingoia Sam Michael Sam Michael Norvin Mohesky Norvin Mohesky Gerry Palva Gerry Palva Jesse Patton Jesse Patton Tom Pekarek Tom Pekarek Clyde Pearson Clyde Pearson Jerry Rowe Jerry Rowe Davie Rolling Davie Rolling Robert Scheu Robert Scheu Jeff Schneider Jeff Schneider Ed Smith Ed Smith Jerry Smith Jerry Smith Ron Stahara Ron Stahara Al Traut Al Traut Miguel Valbuena Miguel Valbuena Dorman Whitley Dorman Whitley Alan Wilks Alan Wilks

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v v C CLLAAUUSSEE PPAAGGEE 1. Scope...1 1. Scope...1 1.1 1.1 ... ... 11 1.2 1.2 ... ... 11 2.

2. Referenced and Referenced and related related publicationspublications ... ... ... ... ... ... ... ... 11 2.1

2.1 ReferReferenced Americenced American an NatioNational Standards...nal Standards... ... 11 2.2

2.2 RelatRelated ed publipublicatications...ons... .... 22 3.

3. Ratings ...Ratings... ... ... ... ... ... ... ... ... ... ...2...2 3.1

3.1 KilovKilovolt-olt-amperampere e ratinratingsgs ... ... 22 3.2

3.2 VoltaVoltage ge ratinratings gs and and tap tap ratiratings...ngs... ... 22 4.

4. Basic lightning Basic lightning impulse impulse insulation insulation levels levels and and dielectric dielectric test test levelslevels ... ... ... ... ...55 4.1 4.1 ... ... 55 4.2 4.2 ... ... 55 5. 5. Tests ...Tests... ... ... ... ... ... ... ... ... ... ... ...5...5 5.1 5.1 GenerGeneralal ... ... 55 5.2

5.2 DieleDielectric ctric testtests...s... . 55 6.

6. Construction...Construction... ... ... ... ... ... ... ... ... ... ...6...6 6.1

6.1 BushiBushings ngs and and termiterminalsnals ... ... 88 6.2

6.2 AccesAccessory sory equipequipment...ment... ... 2020 6.3

6.3 PolarPolarity, terminaity, terminal l markmarkings, and ings, and angulangular ar displdisplacemacement...ent... ... 2424 6.4

6.4 Oil Oil presepreservatrvation...ion... . 3636 6.5

6.5 Tanks...Tanks... ... 3636 7.

7. Storage and Storage and installation...installation... ... ... ... ... ... ... ... ... ... 3737 7.1

7.1 StoraStoragege ... ... 3737 7.2

7.2 InstInstallatallation...ion... ... 3737 8.

8. Design tests Design tests for for fault fault current current capability capability of of overhead overhead distribution distribution transformer transformer enclosuresenclosures ... ... 3737 8.1

8.1 ObjecObjective...tive... ... 3737 8.2

8.2 DefinDefinitioitions...ns... . 3838 8.3

8.3 GenerGeneral al requirequiremerementsnts ... ... 3838 8.4

8.4 TestsTests ... .. 3838 8.5

8.5 Test numTest number 1 — an arcing fault in an encber 1 — an arcing fault in an enclosurlosuree ... 38.... 38 8.6

8.6 Test numbeTest number 2 r 2 — for enclosur— for enclosures with internaes with internal fusible eleml fusible elements...ents... 39... 39 8.7

8.7 Test Test resulresultsts ... . 3939 Annex A (informative) Informational...40 Annex A (informative) Informational...40

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AMERICAN NATIONAL STANDARD

for Transformers—

Standard For Overhead Type Distribution Transformers,

500 kVA and Smaller: High Voltage, 34500 Volts and Below;

Low Voltage, 7970/13800Y Volts and Below

1. Scope

1.1

This standard is intended for use as a basis for determining the performance, interchangeability, and safety of the This standard is intended for use as a basis for determining the performance, interchangeability, and safety of the equipment covered, and to assist in the

equipment covered, and to assist in the proper selection of such equipment.proper selection of such equipment.

1.2

This standard covers certain electrical, dimensional, and mechanical characteristics and takes into consideration This standard covers certain electrical, dimensional, and mechanical characteristics and takes into consideration certain safety features of single- and three-phase, 60-Hz, mineral-oil-immersed, self-cooled, overhead-type certain safety features of single- and three-phase, 60-Hz, mineral-oil-immersed, self-cooled, overhead-type distribution transformers 500 kVA and smaller, with high voltages 34500 volts and below and low voltages 7970/ distribution transformers 500 kVA and smaller, with high voltages 34500 volts and below and low voltages 7970/ 13800Y volts and below

13800Y volts and below. Such transformers may include one or . Such transformers may include one or more of the following features:more of the following features: 1)

1) HigHigh-vh-voltoltageage, ov, overcercurrurrent ent proprotectectiotionn 2)

2) HigHigh-vh-voltoltageage, ov, oververvololtagtage pre proteotectctionion 3)

3) LowLow-vo-voltaltage, ge, oveovercurcurrerrent nt proprotetectictionon 4)

4) LowLow-v-voltoltageage, ov, oververvoltoltage age proprotectectiotionn

NOTE

NOTE — — For polychlorinated-biphenyl (PCB) For polychlorinated-biphenyl (PCB) contamination in contamination in transformertransformers, refer s, refer to to the latest the latest federal regulations.federal regulations.

2. Referenced and related publications

2.1 Referenced American National Standards

This standard is intended for

This standard is intended for use in conjunction with use in conjunction with the following American National Standards. All characteristics,the following American National Standards. All characteristics, definitions, terminol

definitions, terminology, voltage designationogy, voltage designations, and s, and tests, except as specified herein, shall tests, except as specified herein, shall be in accordance with be in accordance with thesethese referenced American National Standards. When the following referenced standards are superseded by a revision referenced American National Standards. When the following referenced standards are superseded by a revision approved by the

approved by the American National Standards Institute, Inc., the latest revision American National Standards Institute, Inc., the latest revision shall applyshall apply.. ANSI C57.12.70,

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2

ANSI C57.12.20-1997 ANSI C57.12.20-1997

ANSI C135.1,

ANSI C135.1, Galvanized Steel Bolts and Nuts for Overhead Line ConstructionGalvanized Steel Bolts and Nuts for Overhead Line Construction ANSI/IEEE C37.40 and C37.40a,

ANSI/IEEE C37.40 and C37.40a, Service Conditions and Definitions for High-Voltage Fuses, Distribution Enclosed Service Conditions and Definitions for High-Voltage Fuses, Distribution Enclosed Single-Pole Air Switches, Fuse

Single-Pole Air Switches, Fuse Disconnecting Switches, and AccessoriesDisconnecting Switches, and Accessories ANSI/IEEE C37.41,

ANSI/IEEE C37.41, Design Design Tests Tests for for High-Voltage High-Voltage Fuses, Fuses, Distribution Distribution Enclosed Enclosed Single-Pole Single-Pole Air Air Switches, Switches, FuseFuse Disconnecting Switches, and Accessories

Disconnecting Switches, and Accessories ANSI/IEEE C57.12.00,

ANSI/IEEE C57.12.00, General Requirements for Liquid-Immersed Distribution, Power, and RegulatingGeneral Requirements for Liquid-Immersed Distribution, Power, and Regulating Transformers

Transformers

ANSI/IEEE C57.12.80,

ANSI/IEEE C57.12.80, Terminology for Power and Distribution TransformersTerminology for Power and Distribution Transformers ANSI/IEEE C57.12.90,

ANSI/IEEE C57.12.90, TTest Code est Code for Liquid-Immersed for Liquid-Immersed Distribution, PowerDistribution, Power, and , and Regulating Transformers and GuideRegulating Transformers and Guide for Short-Circuit T

for Short-Circuit Testing of Distribution and Power Tranesting of Distribution and Power Transformerssformers ANSI/IEEE C57.91,

ANSI/IEEE C57.91, Guide for Loading Mineral-Oil-Immersed Overhead and Pad-Mounted DistributionGuide for Loading Mineral-Oil-Immersed Overhead and Pad-Mounted Distribution Transformers Rated 500 kVA and Less with 65

Transformers Rated 500 kVA and Less with 65°°C or 55C or 55° Α° Αverage Winding Riseverage Winding Rise

2.2 Related publications

The following publications are listed for information only and

The following publications are listed for information only and are not essential for the are not essential for the completion of the requirementscompletion of the requirements of this standard: (Latest Revision shall

of this standard: (Latest Revision shall apply)apply) NEMA MG2,

NEMA MG2, Safety Standard for Construction and Guide for Selection, Installation, and Use of Electric MotorsSafety Standard for Construction and Guide for Selection, Installation, and Use of Electric Motors (available from National Electrical Manufacturer

(available from National Electrical Manufacturers Association, 1300 North s Association, 1300 North 17th Street, Suite 1847, 17th Street, Suite 1847, Rosslyn, VirgiRosslyn, Virginiania 22209).

22209). NEMA TR

NEMA TR 1, Transformers, Regulators, and Reactors (available from National Electrical Manufacturers Association,1, Transformers, Regulators, and Reactors (available from National Electrical Manufacturers Association, 1300 North 17th Street, Suite

1300 North 17th Street, Suite 1847, Rosslyn, Virginia 22209).1847, Rosslyn, Virginia 22209). MIL-STD-209C,

MIL-STD-209C, Swinging Eyes and Attachments for Lifting and Tying Down Military Equipment Swinging Eyes and Attachments for Lifting and Tying Down Military Equipment . (available from. (available from Commanding Officer, Naval Publications and Forms, 5801 Tabor Avenue, Philadelphia, PA 19120).

Commanding Officer, Naval Publications and Forms, 5801 Tabor Avenue, Philadelphia, PA 19120).

3. Ratings

3.1 Kilovolt-ampere ratings

Kilovolt-amper

Kilovolt-ampere ratings are continuous and are based on not e ratings are continuous and are based on not exceeding either a 65exceeding either a 65°°C average winding temperature riseC average winding temperature rise or an 80

or an 80°°C hot-spot temperature rise. The temperature rise of the insulating oil shall not exceed 65C hot-spot temperature rise. The temperature rise of the insulating oil shall not exceed 65°°C when measuredC when measured near the top of the tank. Kilovolt-ampere ratings for single-phase and three-phase transformers shall be as shown in near the top of the tank. Kilovolt-ampere ratings for single-phase and three-phase transformers shall be as shown in Table 1. These ratings are based on the usual temperature and altitude service conditions specified in ANSI/IEEE Table 1. These ratings are based on the usual temperature and altitude service conditions specified in ANSI/IEEE C57.12.00 .

C57.12.00 .

3.2 Voltage ratings and tap ratings

3.2.1

V

Voltage ratings for single-phase and three-phase transformers shall be in accordance with oltage ratings for single-phase and three-phase transformers shall be in accordance with Tables 2, 3, and 4. Tables 2, 3, and 4. No tapsNo taps are to be provided unless otherwise specified in accordance with 3.2.2

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ANSI C57.12.20-1997 ANSI C57.12.20-1997

3.2.2 3.2.2

When specified, tap ratings for single- and

When specified, tap ratings for single- and three-phase transformthree-phase transformers shall be in ers shall be in accordance with Table 5. All tap ratingsaccordance with Table 5. All tap ratings shall be at

shall be at rated kilovolt-amperes, except as otherwise indicated. Vrated kilovolt-amperes, except as otherwise indicated. Voltages in Tables 2, oltages in Tables 2, 3, and 4 3, and 4 are without tapsare without taps

Table 1— Kilovolt-ampere ratings Table 1— Kilovolt-ampere ratings

Table 2— Ratings for single-phase

Table 2— Ratings for single-phase transformers (single ratio)transformers (single ratio) S

Siinngglle e PPhhaassee TThhrreee e PPhhaassee 1 100 3300 1 155 4455 2 255 7755 3 377--11//22 111122--11//22 5 500 115500 7 755 222255 1 10000 330000 1 16677 550000 250 250 333 333 500 500 T

Trraannssffoorrmmeer r HHiiggh h VVoollttaaggee MMiinniimmuum m kkVVA A RRaattiinng g ffoor r LLoow w VVoollttaagge e RRaattiinng g ooff::

Rating Rating

BIL BIL

((kkVV)) 112200//224400 (1)(1)

(1)Low-voltage rating of 120/240 volts or 240/480 volts is suitable for series, multiple, or three-wire service (1)Low-voltage rating of 120/240 volts or 240/480 volts is suitable for series, multiple, or three-wire service

277 277 or or 240/480 240/480(1)(1) 2400 2400 or or 4800 4800 7200 or 7200 or 7620 or 7620 or 7970 7970 Table 7 Table 7 Figure Figure Reference Reference 2 2440000//44116600YY 6600 1100 1100 --- --- 99 4 4880000//88332200YY 7755 1100 1100 --- --- 99 7 7220000//1122447700YY 9955 1100 1100 5500 --- 1100 1 122447700GGrrddYY//77220000 9955 1100 1100 5500 --- 66,,77 7 7662200//1133220000YY 9955 1100 1100 5500 --- 1100 1 133220000GGrrddYY//77662200 9955 1100 1100 5500 --- 66,,77 1 122000000 9955 1100 1100 5500 5500 1100,,1111 13 200/22 860Y 13 200/22 860Y (2)(2)

(2) Suitable for wye-connection on systems where ground connections permit the use of 18-kV arresters (2) Suitable for wye-connection on systems where ground connections permit the use of 18-kV arresters

1 12255 1100 1100 5500 5500 1100,,1111 1 133220000 9955 1100 1100 5500 5500 1100,,1111 1 133880000GGrrddYY//77997700 9955 1100 1100 5500 --- 66,,77 13 800/23 900Y 13 800/23 900Y(2)(2) 112255 1100 1100 5500 5500 1100,,1111 1 133880000 9955 1100 1100 5500 5500 1100,,1111 14 400/24 940Y 14 400/24 940Y(2)(2) 112255 1100 1100 5500 5500 1100,,1111 24 940GrdY/14 400 24 940GrdY/14 400(2)(2) 112255 1100 1100 5500 5500 66,,77,,88 1 166334400 9955 1100 1100 5500 5500 1100,,1111 34 500GrdY/19 920 34 500GrdY/19 920(3) (4)(3) (4)

(3) Suitable for wye-connection on systems where ground connections permit the use of 27-kV arresters (3) Suitable for wye-connection on systems where ground connections permit the use of 27-kV arresters (4) 125 KV BIL may be used based on user vendor agreement

(4) 125 KV BIL may be used based on user vendor agreement

1

15500 1100 1100 5500 5500 66,,77,,88 3

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ANSI C57.12.20-1997 ANSI C57.12.20-1997

Table 3— Ratings for single-phase

Table 3— Ratings for single-phase transformers (series — multiple)transformers (series — multiple)

Table 4— Ratings for three-phase transformers Table 4— Ratings for three-phase transformers T

Rating Rating Minimum Minimum BIL BIL (kV) (kV) (1)(1)

(1) Arrester coordination may require higher BIL on Multiple connection than indicated to achieve a minimum protective level of 20%. (1) Arrester coordination may require higher BIL on Multiple connection than indicated to achieve a minimum protective level of 20%.

120/240 120/240 (2)(2)

(2)Low-voltage rating of 120/240 volts or 240/480 volts is suitable for series, multiple, or three-wire service (2)Low-voltage rating of 120/240 volts or 240/480 volts is suitable for series, multiple, or three-wire service

277 277 or or 240/480 240/480(2)(2) 2400 2400 or or 4800 4800 Figure Figure Table 8 Table 8 Reference Reference 2 2440000//44116600Y Y x x 77220000//112 2 447700YY 660 0 x x 9955 1010 1100 5500 1100 4 4116600GGrrddYY//2244000 0 x x 112 2 447700GGrrddYY//77220000 660 0 x x 9955 1100 1100 --- 66, , 77 2 2440000//44116600Y Y x x 77662200//113 3 220000YY 660 0 x x 9955 1010 1100 5500 1100 4 4116600GGrrddYY//2244000 0 x x 113 3 220000GGrrddYY//77662200 660 0 x x 9955 1100 1100 --- 66, , 77 4 4880000//88332200Y Y x x 77220000//112 2 447700YY 775 5 x x 9955 1010 1100 5500 1100 8 8332200GGrrddYY//4488000 0 x x 112 2 447700GGrrddYY//77220000 775 5 x x 9955 1100 1100 --- 66, , 77 4 4880000//88332200Y Y x x 77662200//113 3 220000YY 775 5 x x 9955 1010 1100 5500 1100 8 8332200GGrrddYY//4488000 0 x x 113 3 220000GGrrddYY//77662200 775 5 x x 9955 1100 1100 --- 66, , 77 7 7220000//112 2 447700Y Y x x 114 4 440000//224 4 994400YY 995 5 x x 112255 1100 1100 5500 1100 1 12 2 447700GGrrddYY//7722000 0 x x 224 4 994400GGrrddYY//114 4 440000 995 5 x x 112255 1100 1100 --- 66, , 77 7 7662200//113 3 220000Y Y x x 114 4 440000//224 4 994400YY 995 5 x x 112255 1100 1100 5500 1100 1 13 3 220000GGrrddYY//7766220 0 x x 224 4 994400GGrrddYY//114 4 440000 995 5 x x 112255 1100 1100 --- 66, , 77 T

Rating Rating (1)(1)

(1) All transformers are delta-connected unless otherwise specified (1) All transformers are delta-connected unless otherwise specified

Minimum Minimum B BIIL L ((kkVV)) 220088YY//112200 240 240 or or 480 480 240 240 x x 4 48800 448800YY//227777 2400 or 2400 or 4160Y/2400 4160Y/2400 or 4800 or or 4800 or 8320Y/4800 8320Y/4800 Table 15 Table 15 Figure Figure Reference Reference 2 2440000 4455 3300 3030 3300 3300 --- 1122 4 4116600YY//22440000 6600 3300 --- --- 3300 --- 1122 4 4116600YY 6600 3300 3300 3300 --- --- 1122 4 4116600 6600 3300 3030 3300 3300 --- 1122 4 4880000 6600 3300 3030 3300 3300 --- 1122 8 8332200YY//44880000 7755 3300 --- --- 3300 --- 1122 8 8332200YY 7755 --- 3030 3300 --- --- 1122 7 7220000 7755 3300 3300 3300 3300 115500 1133 1 122000000 9955 3300 3300 3300 3300 115500 1133 1 122447700YY//77220000 9955 3300 --- --- 3300 --- 1133 1 122447700YY 9955 --- 3300 3300 --- --- 1133 1 133220000YY//77662200 9955 3300 --- --- 3300 --- 1133 1 133220000YY 9955 --- 3300 3300 --- --- 1133 1 133220000 9955 3300 --- 3300 3300 115500 1133 1 133880000 9955 3300 3300 3300 3300 115500 1133 1 133880000GGrrddYY//77997700 9595 3300 --- --- 3300 --- 1133 2 244994400GGrrddYY//1144440000 112255 3300 --- --- 3300 --- 1133 3 344550000GGrrddYY//1199992200 115500 3300 --- --- 3300 --- 1133

(11)

ANSI C57.12.20-1997 ANSI C57.12.20-1997

Table 5— Recommended taps for single-phase

Table 5— Recommended taps for single-phase and three-phase transformersand three-phase transformers

NOTE

NOTE — — No taps will No taps will be supplied if be supplied if taps are not taps are not specified.specified.

4. Basic lightning impulse insulation levels and dielectric test levels

4.1

Basic lightning impulse insulatio

Basic lightning impulse insulation levels (BILs) shall be as n levels (BILs) shall be as shown in Tables 2, 3, and 4.shown in Tables 2, 3, and 4.

4.2

Dielectric test levels shall be in

Dielectric test levels shall be in accordance with the distribution levels specified in ANSI/IEEE C57.12.00 accordance with the distribution levels specified in ANSI/IEEE C57.12.00 ..

5. Tests

5.1 General

Except as specified i

Except as specified in 5.2, tests shall be perforn 5.2, tests shall be performed as specified in ANSmed as specified in ANSI/IEEE C57.12.00 I/IEEE C57.12.00 and in ANSI/IEEEand in ANSI/IEEE C57.12.90 .

C57.12.90 .

5.2 Dielectric tests

For single-phase transformers with a BIL of 150 kV or less that have one high-voltage bushing and a high-voltage For single-phase transformers with a BIL of 150 kV or less that have one high-voltage bushing and a high-voltage terminal permanently connected to ground, no applied-voltage test is required. Induced-voltage tests shall be terminal permanently connected to ground, no applied-voltage test is required. Induced-voltage tests shall be performed by applying between the terminals of one winding a voltage that will be developed from the high-voltage performed by applying between the terminals of one winding a voltage that will be developed from the high-voltage line terminals to ground. This voltage shall be

line terminals to ground. This voltage shall be 1000 volts plus 3.46 1000 volts plus 3.46 times the rated transformer winding voltage, but intimes the rated transformer winding voltage, but in no case shall the line-to-ground voltage developed exceed 40 000 volts for 125 kV BIL

no case shall the line-to-ground voltage developed exceed 40 000 volts for 125 kV BIL or 50 000 volts for 150 or 50 000 volts for 150 kV BIL.kV BIL. For this test the neutral terminal shall be grounded. An applied potential test shall be applied on the low-voltage For this test the neutral terminal shall be grounded. An applied potential test shall be applied on the low-voltage winding.

winding.

W

Wiinnddiinng g VVoollttaaggee AAbboovve e RRaattiinngg BBeelloow w RRaattiinngg The Following Options are available for All Voltages:

The Following Options are available for All Voltages: 2400/4160Y 2400/4160Y 4800/8320Y 4800/8320Y 7200/12470Y 7200/12470Y 12 470GrdY/7200 12 470GrdY/7200 7 7662200//113 3 220000YY OOppttiioon n 11 ((22) ) 2 2 - - 11//22%% ((22) ) 2 2 - - 11//22%% 13 200GrdY/7620 13 200GrdY/7620 12 000 12 000 1 13 3 220000//222 2 886600YY OOppttiioon n 22 NNoonnee ((44) ) 2 2 - - 11//22%% 13 200 13 200 13 800GrdY/7970 13 800GrdY/7970 34 500GrdY/19 920 34 500GrdY/19 920 1 13 3 880000//223 3 909000YY 114 4 440000//114 4 110000 113 3 550000//113 3 220000 1 133880000 1144440000//1144101000 1133550000//1133220000 1 14 4 440000//224 4 994400YY NNoonnee 113 3 808000//113 3 220000//112 2 887700//112 2 554400 16 340 16 340(1)(1)

(1)Single Phase Only. (1)Single Phase Only.

1

17 7 220000//116 6 777700 115 5 991100//115 5 448800 2

(12)

6

ANSI C57.12.20-1997 ANSI C57.12.20-1997

6. Construction

For the purpose of this standard, two principal reference locations have been established, as shown in Figures 1 For the purpose of this standard, two principal reference locations have been established, as shown in Figures 1 and 2.and 2. The first of these is a horizontal plane that passes through the top of the bolt slot in the upper support lug. For the The first of these is a horizontal plane that passes through the top of the bolt slot in the upper support lug. For the second, the transformer cover has been divided into four segments. The segments are numbered in a clockwise second, the transformer cover has been divided into four segments. The segments are numbered in a clockwise direction with the centerline of segment 1 on the centerline of the low-voltage bushings, as shown

direction with the centerline of segment 1 on the centerline of the low-voltage bushings, as shown in Figures 1 and 2.in Figures 1 and 2.

Figure 1— Segment designations and interchangeability dimensions for Figure 1— Segment designations and interchangeability dimensions for

single phase transformers single phase transformers

(13)

ANSI C57.12.20-1997 ANSI C57.12.20-1997

Figure 2— Segment designations and i

(14)

8

ANSI C57.12.20-1997 ANSI C57.12.20-1997

Table 6— Electrical characteristics of bushings Table 6— Electrical characteristics of bushings

6.1 Bushings and terminals

6.1.1 Bushings

6.1.1 Bushings 6.1.1.1

6.1.1.1

Electrical characterist

Electrical characteristics of transformer bushings shall ics of transformer bushings shall be as be as listed in Table 6.listed in Table 6.

6.1.1.2 6.1.1.2

The number, location, and arrangement of bushings for

The number, location, and arrangement of bushings for single-phase and three-phase transformsingle-phase and three-phase transformers shall be as ers shall be as shown inshown in Tables 7, 8, 9, and 15, and Figure 3. The centerline of the high-voltage bushings shall be located within the shaded Tables 7, 8, 9, and 15, and Figure 3. The centerline of the high-voltage bushings shall be located within the shaded areas. The positions of high-voltage bushings for three-phase transformers need not be symmetrical. Low-voltage areas. The positions of high-voltage bushings for three-phase transformers need not be symmetrical. Low-voltage bushings shall be of the sidewall or cover type and

bushings shall be of the sidewall or cover type and shall be individually mounted.shall be individually mounted.

6.1.1.3 6.1.1.3

Unless otherwise specified, the color of bushings shall match Light Gray

Unless otherwise specified, the color of bushings shall match Light Gray Number 70, Munsell Notation 5BG7.0/0.4.Number 70, Munsell Notation 5BG7.0/0.4.

6.1.2 Terminals 6.1.2 Terminals 6.1.2.1

6.1.2.1

Terminal details shall be as shown in Figure 4. Terminal details shall be as shown in Figure 4.

6.1.2.2 6.1.2.2

High-voltage bushings of transformer

High-voltage bushings of transformers 200 kV s 200 kV BIL and below shall be BIL and below shall be equipped with tinned, copper-alloy solderlessequipped with tinned, copper-alloy solderless connectors. High-voltage termi

connectors. High-voltage terminal sizes shall be as shown nal sizes shall be as shown in Tables 10 and 11.in Tables 10 and 11.

6.1.2.3 6.1.2.3

Low-voltage termina

Low-voltage terminal sizes shall be as shown in l sizes shall be as shown in Tables 12 and 13.Tables 12 and 13.

6.1.2.4 6.1.2.4

Terminals of low-voltage windings 600 volts and below shall be arranged for vertical take-off. Terminals of low-voltage windings 600 volts and below shall be arranged for vertical take-off.

6.1.2.5 6.1.2.5

External spacing between low-voltage bushing terminals shall be

External spacing between low-voltage bushing terminals shall be such as to such as to provide the maximum clearance betweenprovide the maximum clearance between live metal parts in the working area. For low-voltage ratings above 600 volts, the electrical characteristics of the live metal parts in the working area. For low-voltage ratings above 600 volts, the electrical characteristics of the bushings determine the spacing. For low-voltage ratings 600 volts and below, spacings shall be within the limits of bushings determine the spacing. For low-voltage ratings 600 volts and below, spacings shall be within the limits of Table 14. Table 14. BIL Withstand (kV) BIL Withstand (kV) Creepage Distance Creepage Distance (1)(1)

(1)Creepage distances are minimum values where no tolerance is specified. (1)Creepage distances are minimum values where no tolerance is specified.

60-Hz Dry 60-Hz Dry 1-Minute 1-Minute Withstand Withstand (kV) (kV) 60-Hz Wet 60-Hz Wet 1-Minute 1-Minute Withstand Withstand (kV) (kV) IInncchheess MMiilllliimmeetteerrss

3 300 --- --- 1100 66 4 455 --- --- 1155 1133 6 600 --- --- 2211 2200 7 755 --- --- 2277 2244 9 955 1100--11//22++//--11//22 262677++//--1133 3355 3300 1 15500 1177 443322 6600 5500

Single Phase Transformer Bushings Only Single Phase Transformer Bushings Only 95

95(2)(2)

(2) For 16.34 kV rating only. (2) For 16.34 kV rating only.

1 166--11//2 2 ++//- - 11--11//22 44119 9 ++//- - 3388 3355 3300 1 12255 1166--11//2 2 ++//- - 11--11//22 44119 9 ++//- - 3388 4422 3366 2 20000 2266 666600 8800 7755

(15)

C C o o p p y y r r i i g g h h t t © © 1 1 9 9 9 9 8 8 I I E E E E E E A A l l l l R R i i g g h h t t s s R R e e s s e e r r v v e e d d 9 9 A A N N S S I I C C 5 5 7 7 . . 1 1 2 2 . . 2 2 0 0 -1 1 9 9 9 9 7 7

Table 7— Accessory equipment for

Table 7— Accessory equipment for single-phase transformers (single-ratio)single-phase transformers (single-ratio)

1 1 0 0 C C o o p p A A N N S S I I C C 5 5 7 7 . . 1 1 2 2 . . 2 2 0 0 -1 1 9 9 9 9 7 7

Table 8— Accessory Equipment for

Table 8— Accessory Equipment for Single-Phase Transformers (Series-Multiple)Single-Phase Transformers (Series-Multiple)

O

OuuttlliinneeDDrraawwiinngg FFiigguurree66 FigureFigure77 FigureFigure1010

High Voltage (kV)

High Voltage (kV) 4.16GrdY/2.4 x 12.47GrdY/7.24.16GrdY/2.4 x 12.47GrdY/7.2

4.16GrdY/2.4 x 13.2GrdY/7.62 4.16GrdY/2.4 x 13.2GrdY/7.62 8.32GrdY/4.8 x 12.47GrdY/7.2 8.32GrdY/4.8 x 12.47GrdY/7.2 8.32GrdY/4.8 x 13.2GrdY/7.62 8.32GrdY/4.8 x 13.2GrdY/7.62 12.47GrdY/7.2 x 24.94GrdY/14.4 12.47GrdY/7.2 x 24.94GrdY/14.4 13.2GrdY/7.62 x 24.94GrdY/14.4 13.2GrdY/7.62 x 24.94GrdY/14.4 4.16GrdY/2.4 x 12.47GrdY/7.2 4.16GrdY/2.4 x 12.47GrdY/7.2 4.16GrdY/2.4 x 13.2GrdY/7.62 4.16GrdY/2.4 x 13.2GrdY/7.62 8.32GrdY/4.8 x 12.47GrdY/7.2 8.32GrdY/4.8 x 12.47GrdY/7.2 8.32GrdY/4.8 x 13.2GrdY/7.62 8.32GrdY/4.8 x 13.2GrdY/7.62 12.47GrdY/7.2 x 24.94GrdY/14.4 12.47GrdY/7.2 x 24.94GrdY/14.4 13.2GrdY/7.62 x 24.94GrdY/14.4 13.2GrdY/7.62 x 24.94GrdY/14.4 2.4/4.16Y x 7.2/12.47Y 2.4/4.16Y x 7.2/12.47Y 2.4/4.16Y x 7.62/13.2Y 2.4/4.16Y x 7.62/13.2Y 4.8/8.32Y x 7.2/12.47Y 4.8/8.32Y x 7.2/12.47Y 4.8/8.32Y x 7.62/13.2Y 4.8/8.32Y x 7.62/13.2Y 7.2/12.47Y x 14.4/24.94Y 7.2/12.47Y x 14.4/24.94Y 7.62/13.2Y x 14.4/24.94Y 7.62/13.2Y x 14.4/24.94Y L

Loow w VVoollttaagge e ((vvoollttss)) 66000 0 aannd d BBeellooww 66000 0 aannd d BBeellooww 5050000 0 aannd d BBeellooww Item Item Number Number Selection Selection Reference Reference kVA kVA Accessory Equipment Accessory Equipment 10 10 to to 50 50 10 10 to to 50 50 75 75 to to 100 100 167 167 250 250 to to 5 50000 5500 75 75 to to 167 167 250 250 to to 500 500 1

1 6.5.26.5.2 SSuuppppoorrttlluugg--TTyyppee AA AA BB BB CC AA BB CC

5

5 6.2.36.2.3 LLiiqquuiidd--lleevveellmmaarrkkiinngg XX XX XX XX XX XX XX XX

9

9 6.2.16.2.1 TTaappCChhaannggeerr((wwhheennssppeecciiffiieedd)) XX XX XX XX XX XX XX XX

14

14 6.5.16.5.1 Handhole in coverHandhole in cover(1(1)) XX XX XX XX XX XX XX XX

16

16 6.2.46.2.4 LLiiffttiinnggLLuuggss XX XX XX XX XX XX XX XX

17

17 6.5.4.16.5.4.1 TTaannkkggrroouunnddiinnggpprroovviissiioonn XX XX XX XX XX XX XX XX

19

19 6.5.4.26.5.4.2 TTaannkkggrroouunnddiinnggccoonnnneeccttoorr XX XX XX XX XX --- ---

---20

20 6.5.4.36.5.4.3 Low-voltage grounding connectionLow-voltage grounding connection(2(2)) XX XX XX --- --- --- --- ---21

21 6.5.4.46.5.4.4 Low-voltage grounding provisionLow-voltage grounding provision(3(3)) XX XX XX XX --- XX XX ---22

(16)

1 1 0 0 C C o o p p y y r r i i g g h h t t © © 1 1 9 9 9 9 8 8 I I E E E E E E A A l l l l R R i i g g h h t t s s R R e e s s e e r r v v e e d d A A N N S S I I C C 5 5 7 7 . . 1 1 2 2 . . 2 2 0 0 -1 1 9 9 9 9 7 7

Table 8— Accessory Equipment for

Table 8— Accessory Equipment for Single-Phase Transformers (Series-Multiple)Single-Phase Transformers (Series-Multiple)

O

OuuttlliinneeDDrraawwiinngg FFiigguurree66 FigureFigure77 FigureFigure1010

High Voltage (kV)

High Voltage (kV) 4.16GrdY/2.4 x 12.47GrdY/7.24.16GrdY/2.4 x 12.47GrdY/7.2

4.16GrdY/2.4 x 13.2GrdY/7.62 4.16GrdY/2.4 x 13.2GrdY/7.62 8.32GrdY/4.8 x 12.47GrdY/7.2 8.32GrdY/4.8 x 12.47GrdY/7.2 8.32GrdY/4.8 x 13.2GrdY/7.62 8.32GrdY/4.8 x 13.2GrdY/7.62 12.47GrdY/7.2 x 24.94GrdY/14.4 12.47GrdY/7.2 x 24.94GrdY/14.4 13.2GrdY/7.62 x 24.94GrdY/14.4 13.2GrdY/7.62 x 24.94GrdY/14.4 4.16GrdY/2.4 x 12.47GrdY/7.2 4.16GrdY/2.4 x 12.47GrdY/7.2 4.16GrdY/2.4 x 13.2GrdY/7.62 4.16GrdY/2.4 x 13.2GrdY/7.62 8.32GrdY/4.8 x 12.47GrdY/7.2 8.32GrdY/4.8 x 12.47GrdY/7.2 8.32GrdY/4.8 x 13.2GrdY/7.62 8.32GrdY/4.8 x 13.2GrdY/7.62 12.47GrdY/7.2 x 24.94GrdY/14.4 12.47GrdY/7.2 x 24.94GrdY/14.4 13.2GrdY/7.62 x 24.94GrdY/14.4 13.2GrdY/7.62 x 24.94GrdY/14.4 2.4/4.16Y x 7.2/12.47Y 2.4/4.16Y x 7.2/12.47Y 2.4/4.16Y x 7.62/13.2Y 2.4/4.16Y x 7.62/13.2Y 4.8/8.32Y x 7.2/12.47Y 4.8/8.32Y x 7.2/12.47Y 4.8/8.32Y x 7.62/13.2Y 4.8/8.32Y x 7.62/13.2Y 7.2/12.47Y x 14.4/24.94Y 7.2/12.47Y x 14.4/24.94Y 7.62/13.2Y x 14.4/24.94Y 7.62/13.2Y x 14.4/24.94Y L

Loow w VVoollttaagge e ((vvoollttss)) 66000 0 aannd d BBeellooww 66000 0 aannd d BBeellooww 5050000 0 aannd d BBeellooww Item Item Number Number Selection Selection Reference Reference kVA kVA Accessory Equipment Accessory Equipment 10 10 to to 50 50 10 10 to to 50 50 75 75 to to 100 100 167 167 250 250 to to 5 50000 5500 75 75 to to 167 167 250 250 to to 500 500 1

1 6.5.26.5.2 SSuuppppoorrttlluugg--TTyyppee AA AA BB BB CC AA BB CC

5

5 6.2.36.2.3 LLiiqquuiidd--lleevveellmmaarrkkiinngg XX XX XX XX XX XX XX XX

9

9 6.2.16.2.1 TTaappCChhaannggeerr((wwhheennssppeecciiffiieedd)) XX XX XX XX XX XX XX XX

14

14 6.5.16.5.1 Handhole in coverHandhole in cover(1(1))

(1) Supplied only on units with internal terminal boards. (1) Supplied only on units with internal terminal boards.

X

X XX XX XX XX XX XX XX

16

16 6.2.46.2.4 LLiiffttiinnggLLuuggss XX XX XX XX XX XX XX XX

17

17 6.5.4.16.5.4.1 TTaannkkggrroouunnddiinnggpprroovviissiioonn XX XX XX XX XX XX XX XX

19

19 6.5.4.26.5.4.2 TTaannkkggrroouunnddiinnggccoonnnneeccttoorr XX XX XX XX XX --- ---

---20

20 6.5.4.36.5.4.3 Low-voltage grounding connectionLow-voltage grounding connection(2(2))

(2) For 120/240 volts only. (2) For 120/240 volts only.

X

X XX XX --- --- --- ---

---21

21 6.5.4.46.5.4.4 Low-voltage grounding provisionLow-voltage grounding provision(3(3))

(3) For 240/480 volts and 277 volts. (3) For 240/480 volts and 277 volts.

X

X XX XX XX --- XX XX

---22

22 6.1.2.26.1.2.2 HHiigghh--vvoollttaaggeebbuusshhiinnggtteerrmmiinnaallss XX XX XX XX XX XX XX XX 23

23 6.1.2.36.1.2.3 LLooww--vvoollttaaggeebbuusshhiinnggtteerrmmiinnaallss XX XX XX XX XX XX XX XX 24

24 6.1.1.26.1.1.2 LLooww--vvoollttaaggeebbuusshhiinnggaarrrraannggeemmeenntt XX XX XX XX XX XX XX XX 25

25 6.3.4.1.16.3.4.1.1 NNaammeeppllaatteeLLooccaattiioonn --- XX XX XX XX XX XX XX

28

28 6.3.4.1.26.3.4.1.2 NNaammeeppllaatteeLLooccaattiioonn XX --- --- --- --- --- ---

---30

30 6.3.4.26.3.4.2 NNaammeeppllaattee--TTyyppee AA AA AA AA AA AA AA AA

31

31 6.3.56.3.5 kkVVAArraattiinnggoonnttaannkk XX XX XX XX XX XX XX XX

32

32 6.2.5.16.2.5.1 Pressure-relief valvePressure-relief valve(4(4))

(4) Segment location not specified. Not required if cover design is in accordance with 6.2.5.2. (4) Segment location not specified. Not required if cover design is in accordance with 6.2.5.2.

X

33

33 6.2.26.2.2 SSeerriieess--MMuullttiipplleeDDeevviiccee XX XX XX XX XX XX XX XX

ANSI C57.12.20-1997 ANSI C57.12.20-1997

Table 9— Number of low

Table 9— Number of low voltage terminals and arrangement for single-phase transformersvoltage terminals and arrangement for single-phase transformers kVA Range for High Voltage Rating of 34.5 kV and Below,

kVA Range for High Voltage Rating of 34.5 kV and Below, 14.4/24.94Y kV and Below, 34.5GrdY/19.92 kV and Below 14.4/24.94Y kV and Below, 34.5GrdY/19.92 kV and Below

Low-Voltage Low-Voltage Ratings Ratings (Volts) (Volts) 1 12200//224400 --- --- 1010 --5500((1)1)

(1) Transformers with single high-voltage bushing. See 6.5.4.3. (1) Transformers with single high-voltage bushing. See 6.5.4.3.

10 - 100 10 - 100(1)(1) 167167(1)(1) 250 - 500250 - 500 2 24400//448800 --- --- --- 1100––110000 116677 ---277 277(2)(2)

(2) For 167 kVA and Below, low-voltage grounding provision on centerline below low-voltage terminals. (2) For 167 kVA and Below, low-voltage grounding provision on centerline below low-voltage terminals.

1 100--550000 --- --- --- --- ---2 2440000--44880000 5050--550000 --- --- --- --- ---7 7220000--77997700 --- 5500--550000 --- --- ---

(17)

ANSI C57.12.20-1997 ANSI C57.12.20-1997

Table 9— Number of low

Table 9— Number of low voltage terminals and arrangement for single-phase transformersvoltage terminals and arrangement for single-phase transformers

Table 10— High-voltage terminal si

Table 10— High-voltage terminal sizes for single-phase transformerszes for single-phase transformers kVA Range for High Voltage Rating of 34.5 kV and Below,

kVA Range for High Voltage Rating of 34.5 kV and Below, 14.4/24.94Y kV and Below, 34.5GrdY/19.92 kV and Below 14.4/24.94Y kV and Below, 34.5GrdY/19.92 kV and Below

Low-Voltage Low-Voltage Ratings Ratings (Volts) (Volts) 1 12200//224400 --- --- 1010 --5500((1)1)

(1) Transformers with single high-voltage bushing. See 6.5.4.3. (1) Transformers with single high-voltage bushing. See 6.5.4.3.

10 - 100 10 - 100(1)(1) 167167(1)(1) 250 - 500250 - 500 2 24400//448800 --- --- --- 1100––110000 116677 ---277 277(2)(2)

(2) For 167 kVA and Below, low-voltage grounding provision on centerline below low-voltage terminals. (2) For 167 kVA and Below, low-voltage grounding provision on centerline below low-voltage terminals.

1 100--550000 --- --- --- --- ---2 2440000--44880000 5050--550000 --- --- --- --- ---7 7220000--77997700 --- 5500--550000 --- --- --- ---Size of Terminal Size of Terminal Opening

Opening _Terminal_Terminal Detail Detail Figure Figure

AWG Size of Conductor AWG Size of Conductor Terminal will Accommodate Terminal will Accommodate

kVA Range for High-Voltage kVA Range for High-Voltage

Rating of: Rating of: IInncchheess MMiilllliimmeetteerrss

5 kV 5 kV a

annd d BBeellooww 77..2 2 kkV V - - 3344..5 5 kkVV 5

5//1166 77..99 44aa NNoo. . 8 8 SSoolliid d tto o NNo o 2 2 SSttrraannddeedd 110 0 - - 161677 110 0 - - 550000 5

(18)

---1 1 2 2 C C o o p p y y r r i i g g h h t t © © 1 1 9 9 9 9 8 8 I I E E E E E E A A l l l l R R i i g g h h t t s s R R e e s s e e r r v v e e d d A A N N S S I I C C 5 5 7 7 . . 1 1 2 2 . . 2 2 0 0 -1 1 9 9 9 9 7 7

Table 11— High-voltage line and neutral terminal sizes for three-phase transformers Table 11— High-voltage line and neutral terminal sizes for three-phase transformers

Table 12— Low-voltage terminal sizes

Table 12— Low-voltage terminal sizes for single-phase transformersfor single-phase transformers

Table 13— Low-voltage line and neutral terminal sizes for three-phase transformers Table 13— Low-voltage line and neutral terminal sizes for three-phase transformers

Size of Terminal Size of Terminal

Opening

Opening TerminalTerminal Detail Detail Figure Figure

kVA Range for High-Voltage Rating of: kVA Range for High-Voltage Rating of: IInncchheess MMiilllliimmeetteerrss

5 kV and 5 kV and Below Below 7.2 kV - 16.34 kV 34.5 7.2 kV - 16.34 kV 34.5 GrdY/19.92 kV GrdY/19.92 kV 5

5//1166 77..99 44aa NNoo. . 8 8 SSoolliid d tto o NNo o 2 2 SSttrraannddeedd 330 0 – – 222255 330 0 – – 550000 5

5//88 1155..99 44aa NNo o 6 6 SSoolliid d tto o NNo o 44//00--119 9 SSttrraannddeedd 33000 0 – – 550000

---Si

Size oze of Tef Termrmininal Oal Opepeniningng TeTermrmininalal Detail Detail Figure Figure

kVA Range for Low-Voltage Rating of kVA Range for Low-Voltage Rating of

IInncchheess MMiilllliimmeetteerrss 112200//224400 224400//448800 227777 2244000 0 – – 44880000 7722000 0 – – 77997700 5

5//1166 77..99 44aa NNoo. . 8 8 SSoolliid d tto o NNoo. . 2 2 SSttrraannddeedd --- --- --- 550 0 – – 116677 550 0 – – 550000 5

5//88 1155..99 44aa NNoo. . 6 6 SSoolliid d tto o NNoo. . 44//00--119 9 SSttrraannddeedd 110 0 – – 1155 10 10 – – 2255 110 0 – – 2255 22550 0 – – 550000 ---1

133//1166 2200..66 44aa NNoo. . 2 2 SSoolliid d tto o 33550 0 kkccmmiil l 119 9 SSttrraannddeedd 225 5 – – 5500 337 7 11//2 2 – – 110000 337 7 11//2 2 – – 110000 --- ---1

155//1166 2233..88 44aa NoNo. . 11//0 0 SSoolliid d tto o 55000 0 kkccmmiil l 337 7 SttrraanS nddeedd 7755 --- --- --- ---1

1--11//44 3311..88 44aa NNoo. . 22//0 0 SSoolliid d tto o 1010000 0 kkccmmiil l 661 1 SttrraanS nddeedd 110000 --- --- --- ---S

SppaaddeeHH 44bb --- 116677––225500 161677––550000 161677––225500 ---

---S

SppaaddeeJJ 44cc --- 333333––505000 --- 333333––550000 ---

---Si

Size ze of of TeTermrmininal al OpOpeneniningg TeTermrmininalal Detail Detail Figure Figure Size of Conductor Size of Conductor Terminal will Accommodate Terminal will Accommodate

kVA Range for Low-Voltage Rating of: kVA Range for Low-Voltage Rating of:

IInncchheess MMiilllliimmeetteerrss 220088YY//11220 0 224400 44880 0 YY//22777 7 448800 2244000 0 aannd d aabboovvee 5

5//1166 77..99 44aa NNoo..88SSoolliiddttooNoNo..22SSttrraannddeedd --- --- 3300––115500 5

5//88 1155..99 44aa NNoo. . 6 6 SSoolliid d tto o NNoo. . 44//00--119 9 SttrraanS nddeedd 330 0 – – 4455 330 0 – – 7755 33000 0 – – 550000 1

133//1166 2200..66 44aa NNoo. . 2 2 SSoolliid d tto o 33550 0 kkccmmiil l 119 9 SSttrraannddeedd 75 75 – – 115500 111122--11//2 2 – – 330000 ---1

155//1166 2233..88 44aa NoNo. . 11//0 0 SSoolliid d tto o 55000 0 kkccmmiil l 337 7 SSttrraannddeedd 222255 --- ---1

1--11//44 3311..88 44aa NNoo. . 22//0 0 SSoolliid d tto o 1100000 0 kkccmmiil l 661 1 SSttrraannddeedd 330000 --- ---S SppaaddeeHH 44bb --- --- 550000 ---S SppaaddeeJJ 44cc --- 550000 --- --- C C o o p p y y r r i i g g h h t t © © 1 1 9 9 9 9 8 8 I I E E E E E E A A l l l l R R i i g g h h t t s s R R e e s s e e r r v v e e d d

Table 14— Minimum electrical clearances (low-voltage terminals — 600 volts and below) Table 14— Minimum electrical clearances (low-voltage terminals — 600 volts and below)

Single Phase Single Phase Rating (kVA) Rating (kVA) Three-Phase Three-Phase Rating (kVA) Rating (kVA)

Minimum Clearance Between Live Metal Minimum Clearance Between Live Metal

Parts Parts11

(1) When moveable parts of

(1) When moveable parts of bushing terminals are in the same bushing terminals are in the same relative position.relative position.

Maximum Spacing Between Center Points of Maximum Spacing Between Center Points of

Bushing Terminals Bushing Terminals IInncchheess MMiilllliimmeetteerrss IInncchheess MMiilllliimmeetteerrss 1

10 0 – – 5500 330 0 – – 115500 11--33//4422

(2) When tank dimensions will not permit this

(2) When tank dimensions will not permit this spacing, the spacing may be respacing, the spacing may be re duced by not more than 3/4 inch duced by not more than 3/4 inch (19 mm).(19 mm). 45

4522 99 222299

7

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C C o o p p y y r r i i g g h h t t © © 1 1 9 9 9 9 8 8 I I E E E E E E A A l l l l R R i i g g h h t t s s R R e e s s e e r r v v e e d d 1 1 3 3 A A N N S S I I C C 5 5 7 7 . . 1 1 2 2 . . 2 2 0 0 -1 1 9 9 9 9 7 7

Table 14— Minimum electrical clearances (low-voltage terminals — 600 volts and below) Table 14— Minimum electrical clearances (low-voltage terminals — 600 volts and below)

Single Phase Single Phase Rating (kVA) Rating (kVA) Three-Phase Three-Phase Rating (kVA) Rating (kVA)

Minimum Clearance Between Live Metal Minimum Clearance Between Live Metal

Parts Parts11

(1) When moveable parts of

(1) When moveable parts of bushing terminals are in the same bushing terminals are in the same relative position.relative position.

Maximum Spacing Between Center Points of Maximum Spacing Between Center Points of

Bushing Terminals Bushing Terminals IInncchheess MMiilllliimmeetteerrss IInncchheess MMiilllliimmeetteerrss 1

10 0 – – 5500 330 0 – – 115500 11--33//4422

(2) When tank dimensions will not permit this

(2) When tank dimensions will not permit this spacing, the spacing may be respacing, the spacing may be re duced by not more than 3/4 inch duced by not more than 3/4 inch (19 mm).(19 mm). 45 4522 99 222299 7 755––550000 222255––550000 3322 767622 99 222299 1 1 4 4 C C o o p p A A N N S S I I C C 5 5 7 7 . . 1 1 2 2 . . 2 2 0 0 -1 1 9 9 9 9 7 7

Table 15— Accessory equipment for three-phase transformers Table 15— Accessory equipment for three-phase transformers

O

OuuttlliinneeDDrraawwiinngg FFiigguurree1122(1)(1) Figure 13Figure 13(1)(1)

H

HiigghhVVoollttaaggee((kkVV)) 44..88aannddBBeellooww

8 8..3322Y Y aannd d BBeellooww 77..2 2 tto o 1133..88 12.47Y to 13.2Y 12.47Y to 13.2Y 13.8GrdY/7.97 13.8GrdY/7.97 24.94GrdY/14.4 24.94GrdY/14.4 34.5GrdY/19.92 34.5GrdY/19.92 L

LoowwVVoollttaaggee((vvoollttss)) 660000aannddBBeellooww 55000000aannddBBeellooww

Item Item Number Number Selection Selection R

Reeffeerreennccee kkVVA A AAcccceessssoorry y EEqquuiippmmeenntt 3300 445 5 tto o 7755 11112 2 - - 11//2 2 tto o 330000 550000 3300 445 5 tto o 7755 11112 2 - - 11//2 2 tto o 330000 550000 1

1 66..55..22 SSuuppppoorrttlluugg--TTyyppee AA BB CC --- AA BB CC

---5

5 66..22..33 LLiiqquuiidd--lleevveellmmaarrkkiinngg XX XX XX XX XX XX XX XX

9

9 66..22..11 TTaappChChaannggeerr((wwhheennssppeecciiffiieedd)) XX XX XX XX XX XX XX XX

1

144 66..55..11 HHaannddhhoolle e iin n ccoovveerr(2)(2) --- --- --- --- XX XX XX XX

1

166 66..22..44 LLiiffttiinnggLLuuggss XX XX XX XX XX XX XX XX

1

177 66..55..44..11 TTaannkkggrroouunnddiinnggprropovviissiioonn XX XX XX XX XX XX XX XX

1

199 66..55..44..22 TTaannkkggrroouunnddiinnggccoonnnneeccttoorr XX XX XX XX XX XX XX XX

2

(20)

1 1 4 4 C C o o p p y y r r i i g g h h t t © © 1 1 9 9 9 9 8 8 I I E E E E E E A A l l l l R R i i g g h h t t s s R R e e s s e e r r v v e e d d A A N N S S I I C C 5 5 7 7 . . 1 1 2 2 . . 2 2 0 0 -1 1 9 9 9 9 7 7

Table 15— Accessory equipment for three-phase transformers Table 15— Accessory equipment for three-phase transformers

O

OuuttlliinneeDDrraawwiinngg FFiigguurree1122(1)(1)

(1) To maintain satisfactory mechanical and

(1) To maintain satisfactory mechanical and electrical clearances on small electrical clearances on small kVA ratings, it is permissible to encroach kVA ratings, it is permissible to encroach upon the unshaded area.upon the unshaded area.

Figure 13 Figure 13(1)(1) H

HiigghhVVoollttaaggee((kkVV)) 44..88aannddBBeellooww

8 8..3322Y Y aannd d BBeellooww 77..2 2 tto o 1133..88 12.47Y to 13.2Y 12.47Y to 13.2Y 13.8GrdY/7.97 13.8GrdY/7.97 24.94GrdY/14.4 24.94GrdY/14.4 34.5GrdY/19.92 34.5GrdY/19.92 L

LoowwVVoollttaaggee((vvoollttss)) 660000aannddBBeellooww 55000000aannddBBeellooww

Item Item Number Number Selection Selection R

Reeffeerreennccee kkVVA A AAcccceessssoorry y EEqquuiippmmeenntt 3300 445 5 tto o 7755 11112 2 - - 11//2 2 tto o 330000 550000 3300 445 5 tto o 7755 11112 2 - - 11//2 2 tto o 330000 550000 1

1 66..55..22 SSuuppppoorrttlluugg--TTyyppee AA BB CC --- AA BB CC

---5

5 66..22..33 LLiiqquuiidd--lleevveellmmaarrkkiinngg XX XX XX XX XX XX XX XX

9

9 66..22..11 TTaappChChaannggeerr((wwhheennssppeecciiffiieedd)) XX XX XX XX XX XX XX XX

1

144 66..55..11 HHaannddhhoolle e iin n ccoovveerr(2)(2)

(2) Supplied only on units with internal tap changers. (2) Supplied only on units with internal tap changers.

--- --- --- --- XX XX XX XX

1

166 66..22..44 LLiiffttiinnggLLuuggss XX XX XX XX XX XX XX XX

1

177 66..55..44..11 TTaannkkggrroouunnddiinnggprropovviissiioonn XX XX XX XX XX XX XX XX

1

199 66..55..44..22 TTaannkkggrroouunnddiinnggccoonnnneeccttoorr XX XX XX XX XX XX XX XX

2

211 66..55..44..44 LLooww--vvoollttaaggeegrrogouunnddiinnggpprroovviissiioonn XX XX XX XX XX XX XX XX 2

222 66..11..22..22 HHiigghh--vvoollttaaggeebbuusshhiinnggtteerrmmiinnaallss XX XX XX XX XX XX XX XX

2

233 66..11..22..33 LLooww--vvoollttaaggeebubusshhiinnggtteerrmmiinnaallss XX XX XX XX XX XX XX XX

2

244 66..11..11..22 LLooww--vvoollttaaggeebubusshhiinnggaarrrraannggeemmeenntt XX XX XX XX XX XX XX XX 2

255 66..33..44..11..11 NNaammeeppllaatteeLLooccaattiioonn XX XX XX XX XX XX XX XX

3

300 66..33..44..22 NNaammeeppllaatte e TTyyppee(3)(3)

(3) Nameplate shall show BIL for 34.5GrdY/19.92. (3) Nameplate shall show BIL for 34.5GrdY/19.92.

A

A AA AA AA AA AA AA AA

3

311 66..33..55 kkVVAArraattiinnggoonnttaannkk XX XX XX XX XX XX XX XX

3

322 66..22..55..11 PPrreessssuurree--rreelliieef f vvaallvvee(4)(4)

(4) Segment location not specified. Not required if cover design is in accordance with 6.2.5.2. (4) Segment location not specified. Not required if cover design is in accordance with 6.2.5.2. X

ANSI C57.12.20-1997 ANSI C57.12.20-1997

Table 16— Angular displacement Table 16— Angular displacement

(21)

ANSI C57.12.20-1997 ANSI C57.12.20-1997

Table 16— Angular displacement Table 16— Angular displacement

(22)

16

ANSI C57.12.20-1997 ANSI C57.12.20-1997

NOTE — See 6.1.1.2. NOTE — See 6.1.1.2.

Figure 3— Number of terminals, descriptions,

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ANSI C57.12.20-1997 ANSI C57.12.20-1997

NOTES: NOTES:

1 —

1 — Threaded partThreaded parts of connector shall be remos of connector shall be removeable witveable without removinhout removing bushings.g bushings. 2 —

2 — ConnectoConnector Clamping Bolts shar Clamping Bolts shall be 3/8, 1/2, 5/8, or 3/4 NC threll be 3/8, 1/2, 5/8, or 3/4 NC threads, class 2 fit.ads, class 2 fit. 3 —

3 — One or two connecOne or two connector clamping botor clamping bolts may be used, but U-bollts may be used, but U-bolts or J-bolts shall not be used.ts or J-bolts shall not be used. 4 —

4 — Terminal of low-vTerminal of low-voltage windoltage windings 600 volts and beings 600 volts and below shall be arranged for vertilow shall be arranged for vertical takeoff.cal takeoff. 5 —

5 — Terminals are to be tin plaTerminals are to be tin plated and aluminted and aluminum conductum conductors are to be properly prepaors are to be properly prepared.red. Figure 4a— Terminal details Figure 4a— Terminal details

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18

ANSI C57.12.20-1997 ANSI C57.12.20-1997

Figure 4b— Spade H — Terminal details Figure 4b— Spade H — Terminal details

(25)

ANSI C57.12.20-1997 ANSI C57.12.20-1997

Figure 4c— Spade J — Terminal details Figure 4c— Spade J — Terminal details