1、 The Institute of Electrical and Electronics Engineers, Inc.3 Park Avenue, New York, NY 10016-5997, USACopyright 1987 by the Institute of Electrical and Electronics Engineers, Inc.All rights reserved. Printed in the United States of America.Print:ISBN 0-7381-3649-2 SH95121PDF:ISBN 0-7381-3650-6 SS95
2、121No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without the prior written permission of the publisher.ANSI C57.12.55-1987(R1998)American National Standard for Transformers Used in Unit Installations, Including Unit SubstationsConformance
3、StandardApproved 4/7/86American National Standards Institute, Inc.iiAmerican National StandardApproval 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 National the standards developer.Con
4、sensus is established when, in the judgment of the ANSI Board of Standards Review, substantial agreement hasbeen reached by directly and materially affected interests. Substantial agreement means much more than a simplemajority, but not necessarily unanimity. Consensus requires that all views and ob
5、jections be considered, and that aconcerted effort be made toward their resolution.The use of American National Standards is completely voluntary; their existence does not in any respect precludeanyone, whether he has approved the standards or not, from manufacturing, marketing, purchasing, or using
6、 products,processes, or procedures not conforming to the standards.The American National Standards Institute does not develop standards and will in no circumstances give aninterpretation of any American National Standard. Moreover, no person shall have the right or authority to issue aninterpretatio
7、n of an American National Standard in the name of the American National Standards Institute. Requestsfor interpretations should be addressed to the secretariat or sponsor whose name appears on the title page of thisstandard.CAUTION NOTICE: This American National Standard may be revised or withdrawn
8、at any time. The procedures ofthe American National Standards Institute require that action be taken to reaffirm, revise, or withdraw this standard nolater than five years from the date of approval. Purchasers of American National Standards may receive currentinformation on all standards by calling
9、or writing the American National Standards Institute.iiiForeword(This Foreword is not part of American National Standard C57.12.55-1987.)The High Voltage Apparatus Coordinating Committee (HVACC) was established July 24, 1972 by the Electrical andElectronic Technical Advisory Board (now superseded by
10、 the Electrical and Electronic Standards Management Board)of the American National Standards Institute. The responsibility assigned to HVACC was to review and evaluateexisting American National Standards and other related standards for the purpose of developing a “Draft Standard” forunit substations
11、 and to develop recommendations for (1) correlating requirements of these standards and (2) addingrequirements to these standards appropriate for product evaluation.This standard results from the evaluation of existing American National Standards and the need to add requirements tothese standards fo
12、r the evaluation and conformance certification of dry-type transformers. This document refers to theproposed revision of American National Standard for Dry-Type Transformers, ANSI/IEEE C57.12.01-1979 (now inpreparation).This document includes Appendixes A and B, outlining procedures recommended for
13、qualifying insulation systems;related material is covered in American National Standard Test for Thermal Evaluation of Insulation Systems forVentilated Dry-Type Power and Distribution Transformers, ANSI/IEEE C57.12.56-1984. This standard is not intended to cover application, installation, or operati
14、on of dry-type transformers.Transformers certified under this standard may contain accessories necessary for installation. For the conformancerequirements for such accessories, reference should be made to the American National Standard for each specificaccessory involved. Typical accessories of a pa
15、d-mounted installation are fuses, lightning arresters, circuit breakers,motor starter controls, and the like.Suggestions for improvement of this standard will be welcome. They should be sent to the National ElectricalManufacturers Association, 2101 L Street, NW, Suite 300, Washington, DC 20037.This
16、standard was processed and approved for submittal to ANSI by the Accredited Standards Committee onTransformers, Regulators, and Reactors, C57. Committee approval of the standard does not necessarily imply that allcommittee members voted for its approval. At the time it approved this standard, the C5
17、7 Committee had the followingmembers:I. H. Koponen, Chair C. R. Willmore, Secretary Organization Represented.Name of RepresentativeElectric Light and Power (EL 5.2.3 Yes Yes Not ApplicableExposed live parts permissible 5.1.9 No No YesOperating handles 5.1.16 Locked Cover No RequirementsNo Requiremen
18、tsOperating handles - height 5.1.16 78 inches Maximum78 inches Maximum78 inches MaximumVent openings - “line of sight” restriction5.1.10; 5.1.11 Not Applicable Yes NoDoors (if supplied) 5.1.4 Yes Yes YesDoors - handles lockable 5.1.4 Yes Yes*Either lockable handles or captive fasteners, but not both
19、, are required.NoDoors - captive fasteners 5.1.4 Not Applicable Yes* NoHinge pins - no removable door 5.1.4 Yes No NoLifting provisions 5.1.2 Yes Yes YesGages, valves, etc - locked cover 5.1.18 Yes No NoGuards for exposed fan blades 5.1.19 Not Applicable Yes Not ApplicableCaution and warning signs 8
20、 Yes Yes YesOutdoor EnclosuresMaterial 6.1 Yes Yes YesHinges 6.1 Yes Yes YesGaskets 6.1 Yes Yes YesDoorstop 6.1 Yes Yes YesTypes and design tests 6.2 Yes Yes YesTestsSpray test 7.1 All Types All Types All TypesDust test 7.2 Types 103, 103S, 104Types 103, 103S, 104Types 103, 103S, 104External-icing (
21、sleet) test 7.3 All Types All Types AllTypesHosedown 7.4 Type 104 Type 104 Type 104Corrosion resistance 7.5 Types 103, 103S,104Types 103, 103S,104Types 103, 103S,1044 Copyright 1987 IEEE All Rights ReservedAMERICAN NATIONAL STANDARD C57.12.55-1987 5. Enclosures Basic Requirements5.1 Construction5.1.
22、1 GeneralIf of metal, enclosures shall be suitably supported, constructed, and assembled so that they will have the strength andrigidity necessary to resist the abuses to which they are likely to be subjected, without total or partial collapse that mayresult in an increased fire hazard due to reduct
23、ion of spacings, loosening or displacement of parts, or other seriousdefects. Nonmetallic materials may be used as all or part of an enclosure if found suitable for the application and shallotherwise comply with 5.1.1. Among the factors to be taken into consideration when a nonmetallic material is b
24、eingjudged for acceptability are the following: (1) physical strength, (2) resistance to impact, (3) moisture-absorptiveproperties, (4) combustibility, (5) ground plane between high voltage and enclosure, and (6) resistance to distortion attemperatures to which it may be subjected under conditions o
25、f normal and abnormal use. These factors are consideredwith respect to thermal aging. The enclosure shall be capable of withstanding the tests specified in this standard thatare applicable to the location and environmental conditions to which it will be exposed.5.1.2 Lifting ProvisionsLifting provis
26、ions shall provide a distributed balanced lift in a vertical direction for the assembled transformer andshall be designed to provide a safety factor of five or more. The safety factor of five is the ratio of the ultimate stressof material used to the working stress.1 The working stress is the maximu
27、m combined stress developed in the liftingprovisions by the static lead of the completely assembled transformer.2A spreader bar may be required to lift the complete unit.If lifted from the core and coil by removing the top cover, the maximum angle of lift (measured from vertical) shall be30 degrees.
28、5.1.3 Protection of Inside and Outside SurfacesUnless the enclosure is of a material that will resist corrosion, both inside and outside surfaces shall be suitablyprotected by painting, galvanizing, plating, or other equivalent means.5.1.4 Covers and DoorsIf an enclosure cover is not of the drawout
29、construction type but gives access to fuses or any other overload-protectivedevices the normal functioning of which requiresrenewal, or if it is necessary to open the cover in connection with thenormal operation of the device, the cover shall be hinged.Exception: Fuses for instrument transformers, i
30、nternal fans, and the like may be behind bolted covers.A part of the enclosure such as a door, cover, or panel giving access to the inside of the enclosure shall be providedwith fasteners for firmly securing it in place. Such fasteners shall be so located or used in multiple so as to hold thedoor or
31、 cover closed over its entire length. A hinged cover more than 48 inches (1219 millimeters) long on the hingedside shall have at least a two-point latch operated by a single knob or handle or shall have at least two captive fasteners.1Taken from American National Standard Safety Standard for Constru
32、ction and Guide for Selection, Installation, and Use of Electric Motors andGenerators, ANSI/NEMA MG2-1977, paragraph MC 2-2-03, Lifting Means.2Taken from Specification MIL-STD-209C, Swinging Eyes and Attachments for Lifting and Tying Down Military Equipment, August I, 1968. MILpublications are avail
33、able from the Navy Publications and Forms Center, 5801 Tabor Avenue, Philadelphia, PA 19120.Copyright 1987 IEEE All Rights Reserved 5AMERICAN NATIONAL STANDARD C57.12.55-1987The opening handles for doors in Category A and B enclosures shall be lockable. However, captive fasteners arepermitted on Cat
34、egory B enclosures. Exposed hinge pins shall be nonremovable on doors of Category A enclosures or,as an alternative, the door shall be nonremovable in the closed position.A door or cover shall shut closely against a 1/4-inch (6.4-millimeter) rabbet (as shown in Figure 1) or the equivalent,or shall h
35、ave a minimum overlap of 1/2 inch, or shall have flanges for the full length of the four edges. Flanges on adoor or cover shall fit closely with the outside walls of the enclosure proper and shall not be less than 7/16 inch(11.1millimeters) in depth. A suitable combination of flange and rabbet is ac
36、ceptable. Figure 2 illustrates typicalconstructions that are considered to comply with this requirement. Other constructions may be suitable.Cover plates intended to be removed for inspection and maintenance of energized parts and wiring shall not exceed12square feet (1.11 square meters) in area or
37、60 pounds (27.2 kilograms) in weight unless they are equipped withlifting means or hinges.Figure 1 RabbetFigure 2 Typical Constructions5.1.5 Cast-Metal EnclosuresAn enclosure of cast metal shall be at least 1/8 inch (3.2 millimeters) thick at every point, greater than 1/8 inch(3.2millimeters) thick
38、at reinforcing ribs and door edges, and not less than 1/4 inch (6.4 millimeters) thick at tappedholes for conduit.Exception: At other than plain or threaded conduit holes, die-cast metal shall be:6 Copyright 1987 IEEE All Rights ReservedAMERICAN NATIONAL STANDARD C57.12.55-1987 1) Not less than 3/32
39、 inch (2.4 millimeters) thick for an area greater than 24 square inches (0.015 square meters)or having any dimensions greater than 6 inches (152 millimeters).2) Not less than 1/16 inch (1.6 millimeters) thick for an area of 24 square inches (0.015 square meters) or lessand having no dimensions great
40、er than 6 inches (152 millimeters). The area limitation may be obtained by theprovision of suitable reinforcing ribs subdividing a larger area.5.1.6 Sheet-Metal EnclosuresThe thickness of a sheet-metal enclosure shall not be less than that indicated in Tables 2 and 3 except (1) that uncoatedsteel sh
41、all not be less than 0.032 inch (0.81 millimeter) thick, zinc-coated steel shall not be less than 0.034 inch(0.86millimeter) thick, and nonferrous metal shall not be less than 0.045 inch (1.14 millimeter) thick at points atwhich a wiring system is to be connected, and (2) as indicated in 5.2.1 and 5
42、.2.3.Tables 2 and 3 are based on a uniform deflection of the enclosure surface for any given load concentrated at the centerof the surface regardless of metal thickness.Table 2 Minimum Thickness of Sheet Metal for Enclosures of Carbon Steel or Stainless SteelWithout Supporting Frame*See 5.1.7 for su
43、pporting frame.With Supporting Frame or or equivalent Reinforcing*Minimum Thickness in Inches (millimeters)Maximum Width in Inches (millimeters)The width is the smaller dimension of a rectangular sheet metal piece that is part of an enclosure. Adjacent surfaces of an enclosure may havesupports in co
44、mmon and be made from a single sheet.Maximum Length in Inches (millimeters)For panels that are not supported along one side (for example, side panel of boxes) the length of the unsupported side shall be limited to thedimensions specified.Maximum Width in Inches (millimeters)Maximum Length in Inches
45、(millimeters) Uncoated Zinc-Coated4.0 (101) Not limited*”Not limited” applies only if the edge of the surface is flanged at least 1/2 inch (12.7 mm) or fastened to adjacent surfaces not normally removedin use.6.25 (159) Not limited* 0.020 (0.51)Sheet steel for an enclosure for outdoor use (rainproof
46、 or raintight)is required to be not less than 0.034 inch (0.86 mm) in thickness if zine-coatedand not less than 0.032 inch (0.81 mm) in thickness if uncoated.0.023 (0.058)4.75 (121) 5.75 (146) 6.75 (171) 8.25 (210)6.0 (152) Not limited 9.5 (241) Not limited 0.026 (0.66) 0.029 (0.74)7.0 (178) 8.75 (2
47、22) 10.0 (254) 12.5 (318)8.0 (203) Not limited 12.0 (305) Not limited 0.032 (0.81) 0.034 (0.86)9.0 (229) 11.5 (292) 13.0 (330) 16.0 (406)12.5 (318) Not limited 19.5 (495) Not limited 0.042 (1.07) 0.045 (1.14)14.0 (356) 18.0 (457) 21.0 (533) 25.0 (635)18.0 (457) Not limited 27.0 (686) Not limited 0.0
48、53 (1.35) 0.056 (1.42)20.0 (508) 25.0 (635) 29.0 (737) 36.0 (914)22.0 (559) Not limited 33.0 (838) Not limited 0.060 (1.52) 0.063 (1.60)25.0 (635) 31.0 (787) 35.0 (889) 43.0 (1092)25.0 (635) Not limited 39.0 (991) Not limited 0.067 (1.70) 0.070 (1.78)29.0 (737) 36.0 (914) 41.0 (1041) 51.0 (1295)33.0
49、 (838) Not limited 51.0 (1295) Not limited 0.080 (2.03) 0.084 (2.13)38.0 (965) 47.0 (1194) 54.0 (1372) 66.0 (1676)42.0 (1067) Not limited 64.0 (1626) Not limited 0.093 (2.36) 0.097 (2.46)47.0 (1194) 59.0 (1499) 68.0 (1727) 84.0 (2134)52.0 (1321) Not limited 80.0 (2032) Not limited 0.108 (2.74) 0.111 (2.82)60.0 (1524) 74.0 (1880) 84.0 (2134) 103.0 (2616)63.0 (1600) Not limited 97.0 (2464) Not limited 0.123 (3.12) 0.126 (3.20)73.0 (1854) 90.0 (2286) 103.0 (2616) 127.0 (3226)Copyright 1987 IEEE All Rights Reserved 7AMERICAN NATIONAL STANDARD C57.12
