IEEE Std C57.148-2011, IEEE Standard for Control Cabinets for Power Transformers
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IEEE Standard for Control Cabinets for Power Transformers IEEE Power & Energy Society Sponsored by the Transformers Committee IEEE 3 Park Avenue New York, NY 10016-5997 USA IEEE Std C57.148™-2011 3 January 2012 Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148™-2011 IEEE Standard for Control Cabinets for Power Transformers Sponsor Transformers Committee of the IEEE Power & Energy Society Approved 10 September 2011 IEEE-SA Standards Board Approved 15 January 2013 American National Standards Institute Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. Abstract: Requirements for the design and construction of control cabinets on power transformers. Keywords: cabinet, circuit, component, construction, control cabinet, controls, current transformer, design, IEEE C57.148, layout, manufacture • The Institute of Electrical and Electronics Engineers, Inc. 3 Park Avenue, New York, NY 10016-5997, USA Copyright © 2012 by the Institute of Electrical and Electronics Engineers, Inc. All rights reserved. Published 3 January 2012. Printed in the United States of America. National Electrical Code, NEC, and NFPA 70 are registered trademarks in the U.S. Patent & Trademark Office, owned by the National Fire Protection Association. IEEE is a registered trademark in the U.S. Patent & Trademark Office, owned by the Institute of Electrical and Electronics Engineers, Incorporated. PDF: Print: ISBN 978-0-7381-6805-0 ISBN 978-0-7381-6806-7 STD97164 STDPD97164 IEEE prohibits discrimination, harassment, and bullying. For more information, visit http://www.ieee.org/web/aboutus/whatis/policies/p9-26.html. 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Comments and recommendations on standards should be addressed to: Secretary, IEEE-SA Standards Board 445 Hoes Lane Piscataway, NJ 08854-4141 USA Authorization to photocopy portions of any individual standard for internal or personal use is granted by The Institute of Electrical and Electronics Engineers, Inc., provided that the appropriate fee is paid to Copyright Clearance Center. To arrange for payment of licensing fee, please contact Copyright Clearance Center, Customer Service, 222 Rosewood Drive, Danvers, MA 01923 USA; +1 978 750 8400. Permission to photocopy portions of any individual standard for educational classroom use can also be obtained through the Copyright Clearance Center. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. Introduction This introduction is not part of IEEE Std C57.148-2011, IEEE Standard for Control Cabinets for Power Transformers. This standard is intended to provide requirements for the design and manufacture of control cabinets for Class I and Class II power transformers. The standard also contains options to cover the various types of components that could be provided, the various types of cooling classes that may be employed, and the various site-specific or user-specified requirements that may exist for the transformer. Notice to users Laws and regulations Users of these documents should consult all applicable laws and regulations. Compliance with the provisions of this standard does not imply compliance to any applicable regulatory requirements. Implementers of the standard are responsible for observing or referring to the applicable regulatory requirements. IEEE does not, by the publication of its standards, intend to urge action that is not in compliance with applicable laws, and these documents may not be construed as doing so. Copyrights This document is copyrighted by the IEEE. 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Further information may be obtained from the IEEE Standards Association. v Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. Participants At the time this IEEE standard was completed, with guidance from the Power Transformers Subcommittee, the Control Cabinets of Power Transformers Working Group had the following membership: Joe Watson, Chair Steven Schappell, Vice Chair David Aho Jerry Allen Gregory Anderson Stephen Antosz Javier Arteaga Donald Ayers Peter Balma Ron Barker Thomas Bassett Barry Beaster Stephen Beckman Oscar Bello Enrique Betancourt Carlos Bittner Gene Blackburn Dennis Blake Daniel Blaydon William Boettger Joseph Cheung Donald Chu Craig Colopy Dan de la Cruz William Darovny Ronald Daubert Dieter Dohnal James Bruce Fairris Jeffrey Fleeman Jean-Philippe Gagnon Eduardo Garcia Andreas Garnitschnig Saurabh Ghosh Harry Gianakouros Eduardo Gomez-Hennig James Graham Jorge Guerra Everett Hager, Jr. Wayne Hansen Thomas Harbaugh Robert Hartgrove Gary Hartman Gary Hoffman Timothy Huff Catherine Hurley Murray Joyner David Keithly Stanley Kostyal Krzysztof Kulasek Michael Lau Thomas Lundquist Michael Martin John Matthews Joseph Melanson Jerry Murphy Ryan Musgrove Steve Northrup Bipin Patel Sanjay Patel Paulette Powell John Progar Martin Rave Randolph Rensi Marnie Roussell Subhas Sarkar Dinesh Sankarakurup Steven Schroeder Ewald Schweiger Dilipkumar Shah Devki Sharma Hemchandra Shertukde Manuel Silvestre H. Jin Sim Joao Sousa Andrew Steineman Craig Stiegemeier Raman Subramanian Craig Swinderman Mark Teetsel Malcolm Thaden Roger Verdolin Jane Ann Verner David Wallach Ronald Wiefling Frank Wolfe Jennifer Yu Kipp Yule Peter Zhao The following members of the individual balloting committee voted on this standard. Balloters may have voted for approval, disapproval, or abstention. Satish Aggarwal Steven Alexanderson Stephen Antosz Stan Arnot Donald Ayers Peter Balma David Bassett Barry Beaster W. J. Bill Bergman Wallace Binder Thomas Blackburn Daniel Blaydon William Boettger Steven Brockschink Chris Brooks Suresh Channarasappa Jerry Corkran John Crouse William Darovny Gary Donner Michael Dood Randall Dotson Fred Elliott Gary Engmann James Fairris Rabiz Foda Bruce Forsyth Marcel Fortin Saurabh Ghosh Jalal Gohari Edwin Goodwin James Graham William Griesacker Charles Grose Randall Groves Bal Gupta Ajit Gwal J. Harlow David Harris Robert Hartgrove Steven Hensley Lee Herron Gary Heuston Gary Hoffman Philip Hopkinson David Horvath Laszlo Kadar John Kay vi Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. Ryan Musgrove K. R. M. Nair Anthony Napikoski Bradley Nelson Michael S. Newman Joe Nims Gary Nissen Mohamed Omran Bansi Patel Paul Pillitteri Alvaro Portillo Bertrand Poulin Lewis Powell Iulian Profir Jean-Christophe Riboud John Rossetti Marnie Roussell M. Sachdev Dinesh Sankarakurup Bartien Sayogo Hamidreza Sharifnia Gael Kennedy Sheldon Kennedy Yuri Khersonsky Morteza Khodaie J. Koepfinger Neil Kranich Jim Kulchisky Saumen Kundu John Lackey Chung-Yiu Lam Hua Liu Albert Livshitz Thomas Lundquist Greg Luri J. Dennis Marlow John W. Matthews Joseph Melanson Daleep Mohla Georges Montillet Kimberly Mosley Jerry Murphy Devki Sharma Stephen Shull Gil Shultz James Smith Jerry Smith Zareh Soghomonian Gary Stoedter John Tengdin David Tepen Malcolm Thaden John Toth Joe Uchiyama John Vergis Jane Verner Keith Wallace David Wallach Barry Ward Joe Watson Kenneth White Kipp Yule Matthew Zeedyk When the IEEE-SA Standards Board approved this standard on 10 September 2011, it had the following membership: Richard H. Hulett, Chair John Kulick, Vice Chair Robert M. Grow, Past Chair Judith Gorman, Secretary Masayuki Ariyoshi William Bartley Ted Burse Clint Chaplin Wael Diab Jean-Philippe Faure Alexander Gelman Paul Houzé Jim Hughes Joseph L. Koepfinger* David J. Law Thomas Lee Hung Ling Oleg Logvinov Ted Olsen Gary Robinson Jon Walter Rosdahl Sam Sciacca Mike Seavey Curtis Siller Phil Winston Howard L. Wolfman Don Wright *Member Emeritus Also included are the following nonvoting IEEE-SA Standards Board liaisons: Satish Aggarwal, NRC Representative Richard DeBlasio, DOE Representative Michael Janezic, NIST Representative Francesca Drago IEEE Standards Program Manager, Document Development Erin Spiewak IEEE Standards Program Manager, Technical Program Development vii Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. Contents 1. Overview .................................................................................................................................................... 1 1.1 Scope ................................................................................................................................................... 1 1.2 Purpose ................................................................................................................................................ 1 2. Normative references.................................................................................................................................. 1 3. Definitions, acronyms, and abbreviations .................................................................................................. 2 3.1 Definitions ........................................................................................................................................... 2 3.2 Acronyms and abbreviations ............................................................................................................... 3 4. Cabinet-ordering specifications.................................................................................................................. 4 5. Standard cabinet construction..................................................................................................................... 4 5.1 General ................................................................................................................................................ 4 5.2 Cabinet-housing criteria....................................................................................................................... 4 5.3 Cabinet dimensions.............................................................................................................................. 4 5.4 Cabinet construction materials............................................................................................................. 5 5.5 Compartment styles and welding......................................................................................................... 5 5.6 Rain sheds............................................................................................................................................ 6 5.7 Fixed back and side panels .................................................................................................................. 6 5.8 Swing panels........................................................................................................................................ 6 5.9 Doors, hardware, and gaskets .............................................................................................................. 6 5.10 Ventilation and drains........................................................................................................................ 7 5.11 Location of conduit entry points........................................................................................................ 7 5.12 Bottom plate for cable entrance ......................................................................................................... 7 5.13 Grounding of panels and doors.......................................................................................................... 7 5.14 Finish coatings................................................................................................................................... 8 5.15 External cabinet grounding and grounding terminals ........................................................................ 8 5.16 General cabinet layout ....................................................................................................................... 8 5.17 Internal ground connections and ground bus ..................................................................................... 9 5.18 Lights and ac power outlet................................................................................................................. 9 5.19 Wiring................................................................................................................................................ 9 5.20 Circuit protection............................................................................................................................. 10 5.21 Contactors........................................................................................................................................ 11 5.22 Heaters............................................................................................................................................. 11 5.23 AC power and cooling control circuits ............................................................................................ 11 6. Numbering and labeling system ............................................................................................................... 12 6.1 Device numbers ................................................................................................................................. 12 6.2 Current transformer numbering ......................................................................................................... 12 6.3 Terminal block, device, and terminal labels ...................................................................................... 13 6.4 Current transformer circuit terminal block, terminal, test switch, and secondary wiring numbers ... 13 6.5 Control, alarm, and trip-circuit terminal blocks and terminal numbers ............................................. 14 6.6 Wire markers ..................................................................................................................................... 15 6.7 Wiring diagrams ................................................................................................................................ 16 7. Cabinet construction options .................................................................................................................... 16 7.1 General .............................................................................................................................................. 16 7.2 Option B: Sheet metal thickness........................................................................................................ 16 7.3 Option C: AC power and dc relay voltages ....................................................................................... 16 7.4 Option D: Terminals, terminal blocks, wire raceways, and wire bundling........................................ 17 viii Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. 7.5 Option E: Cooling control switches................................................................................................... 19 7.6 Option F: Annunciator....................................................................................................................... 20 7.7 Option G: Automatic transfer switch................................................................................................. 20 7.8 Option H: Dead-front cabinet design................................................................................................. 21 7.9 Option I: Visible air gap .................................................................................................................... 21 Annex A (normative) Figures....................................................................................................................... 23 Annex B (informative) Forms ...................................................................................................................... 34 B.1 Sample ordering form ....................................................................................................................... 34 B.2 Annunciator table and checklist ........................................................................................................ 36 ix Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Standard for Control Cabinets for Power Transformers IMPORTANT NOTICE: This standard is not intended to ensure safety, security, health, or environmental protection. Implementers of the standard are responsible for determining appropriate safety, security, environmental, and health practices or regulatory requirements. This IEEE document is made available for use subject to important notices and legal disclaimers. These notices and disclaimers appear in all publications containing this document and may be found under the heading “Important Notice” or “Important Notices and Disclaimers Concerning IEEE Documents.” They can also be obtained on request from IEEE or viewed at http://standards.ieee.org/IPR/disclaimers.html. 1. Overview 1.1 Scope This standard will provide minimum and optional function, layout, and construction requirements for standard control cabinet designs. It will also include a coding system for specifying standard control cabinets with the required options. This standard will apply to Class 1 and Class 2 power transformers and will not apply to distribution or padmount design transformers. 1.2 Purpose This document will provide users and manufacturers with a set of standard designs that can be easily specified. The document should greatly reduce the engineering time required by manufacturers to create and by users to review control cabinet designs. 2. Normative references The following referenced documents are indispensable for the application of this document (i.e., they must be understood and used, so each referenced document is cited in text and its relationship to this document is explained). For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments or corrigenda) applies. 1 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers ANSI/ASME B1.1, Unified Inch Screw Threads (UN and UNR Thread Form).1 ANSI Z55.1, Gray Finishes for Industrial Apparatus and Equipment (R1973).2 DIN EN 50022, Specification for low voltage switchgear and control-gear for industrial use. Mounting rails. Top hat rails 35 mm wide for snap-on mounting of equipment. IEC Publication 60529, Classification of Degrees of Protection Provided by Enclosures.3 IEEE Std C37.2™, IEEE Standard for Electrical Power System Device Function Numbers, Acronyms, and Contact Designations.4, 5 IEEE Std C57.12.00™, IEEE Standard for General Requirements for Liquid-Immersed Distribution, Power, and Regulating Transformers. IEEE Std C57.12.10™, IEEE Standard Requirements for Liquid-Immersed Power Transformers. ISO 262, ISO General purpose metric screw threads ― Selected sizes for screws, bolts, and nuts.6 NEMA 250, Enclosures for Electrical Equipment (1000 Volts Maximum).7 NFPA 70, National Electrical Code® (NEC®).8 3. Definitions, acronyms, and abbreviations 3.1 Definitions For the purposes of this document, the following terms and definitions apply. The IEEE Standards Dictionary: Glossary of Terms & Definitions should be consulted for terms not defined in this clause.9 control cabinet: The primary cabinet(s) on a Class I or Class II transformer that contains the control panels for relay, metering, alarms, cooling controls, auxiliary power, and related circuits for user connection to the related systems in the substation. control cabinet designer: The engineer or designer responsible for designing the layout and circuitry in the control cabinet. DIN rail: A standard 35-mm-wide metal rail used to mount terminals, circuit breakers, and other types of devices (as specified in DIN EN 50022). 1 ASME publications are available from the American Society of Mechanical Engineers, http://www.asme.org/. ANSI Z55.1 (R1973) has been withdrawn; however, copies can be obtained from the Sales Department, American National Standards Institute, http://www.ansi.org/. 3 This IEC publication is available from http://standards.ieee.org/store. 4 The IEEE standards or products referred to in this clause are trademarks of the Institute of Electrical and Electronics Engineers, Inc. 5 IEEE publications are available at http://standards.ieee.org/. 6 ISO/IEC publications are available at http://www.iso.org/ or http://www.ansi.org/. 7 This NEMA publication is available at http://shop.ieee.org/. 8 National Electrical Safety Code and NESC are both registered trademarks and service marks of the Institute of Electrical and Electronics Engineers, Inc. 9 The IEEE Standards Dictionary: Glossary of Terms & Definitions is available at http://shop.ieee.org/. 2 2 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers fluorinated ethylene propylene (FEP): A compound used for wire and cable insulation and jackets. ground fault interrupter (GFI): A device commonly used for protection of personnel or some circuits by fast tripping for differential current in the neutral and phase wires of a circuit. machine tool wire: A flexible, stranded wire with a polyvinylchloride (PVC) insulation and jacket compound. manufacturer: The organization that constructs or supplies the device or equipment. piano hinge: A long hinge with one continuous pin, attached along the full available lengths of a door and frame. Also referred to as a continuous hinge. positive temperature coefficient (PTC) heater: A type of heater that provides self-regulating temperature control resulting from the thermal-resistive properties of the ceramic materials used for the heating elements. supplier: Refers to the transformer manufacturer when the control cabinet has been ordered by the transformer manufacturer, or refers to the control cabinet manufacturer when the control cabinet has been ordered directly from the control cabinet manufacturer by the user. switchboard wire: A flexible, stranded, tin-coated wire, with a cross-linked polyethylene insulation and jacket compound. user: The organization, or representative of the organization, who specifies and orders the purchase of the transformer and/or control cabinet and will own and operate the transformer and/or control cabinet when it is received and placed in service. As used in the introductory sections before the Contents, the term refers to the user of this standard. wire raceway: A channel, with or without a cover, designed to contain and route wires and cables adjacent to terminal blocks and other devices. 3.2 Acronyms and abbreviations AWG American Wire Gauge CT current transformer DIN Deutsches Institut für Normung e.V. (German Institute for Standardization) ETFE ethylene-tetrofluoroethylene FEP fluorinated ethylene propylene GFI ground fault interrupter MTW machine tool wire OEM original equipment manufacturer ODAF oil directed air forced OFAF oil forced air forced ONAF oil natural air forced ONAN oil natural air natural SIS switchboard wire XLP cross-linked polyethylene 3 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers 4. Cabinet-ordering specifications This standard includes requirements that are intended to provide a basic, standard design. This standard also provides options on many aspects of the design and construction. Additionally, the user may specify and require other options. A sample ordering form is included in Annex B to provide a convenient and complete method of communicating the purchaser’s selection of standard design, standard options or users’ options for all aspects of the control cabinet. 5. Standard cabinet construction 5.1 General The following standard cabinet construction requirements shall apply to all control cabinets covered under this standard. Note that references herein to the National Electric Code® (NEC®) (NFPA 70®) are not intended to include the complete NEC as a normative reference. All references to the NEC in this standard are specific to the topic covered in the clauses containing the references only, and any other NEC requirements not referenced in this document do not apply to control cabinets covered under this standard. 5.2 Cabinet-housing criteria Unless specified otherwise, the complete cabinet shall be constructed for outdoor use to meet or exceed the NEMA 3R designation as detailed in NEMA 250. For special application environments such as corrosive or chemical atmospheres, marine or explosion proof requirements, the appropriate NEMA or IEC designations shall be specified by the user. The NEMA Type performance requirements are defined in NEMA 250 “Enclosures for Electrical Equipment (1000 Volts Maximum)”. The IEC designations are defined in IEC 60529 “Degrees of Protection Provided by Enclosures (IP)”. Cabinets with gross weight greater than 20 kg (44.1 lb) shall have provisions for lifting and a sufficient number of external tabs for the purpose of bolting to the transformer. Additional external brackets for mounting gauges shall be specified by the transformer manufacturer or user. Cabinet mounting provisions must meet the specified requirements of the user or supplier, respectively, depending on who orders the cabinet from the manufacturer. One such requirement is the ability to accommodate vibration suppressors or similar mounting hardware. Unless specified otherwise by the user or supplier, the control cabinet designer should design the cabinet to be mounted on the transformer with not less than a 200 mm (7.9 in) air space between the back of the cabinet and the transformer tank wall. 5.3 Cabinet dimensions Cabinet height and depth shall be such that all switches, circuit breakers, fuses, device display panels, and all similar components that require operation, adjustment, or inspection during normal operation can be comfortably reached by a person of average height (approximately 1.7 m, or 5 ft 7 in) when standing at the plane of the door. The mounted location of the control cabinet should be determined by the supplier based on user specifications, transformer foundation design, shipping limitations, and other considerations. Unless otherwise specified by the user, the bottom of the control cabinet shall not be less than 0.5 m (19.7 in) above 4 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers the location where a worker, standing in front of the control cabinet on the ground or on a work platform when the transformer is set on its foundation, and shall not be below the base of the transformer. Unless specified otherwise by the user, the control cabinet designer shall assume that the elevation of the location where a technician would stand in front of the control cabinet in order to work in the cabinet shall be the same elevation as the base of the transformer. 5.4 Cabinet construction materials Cabinets, doors, and hardware shall be of sturdy construction, and capable of operation under usual service conditions for transformers as specified in IEEE Std C57.12.00 for the expected life of the transformer, without bending or warping. Unless specified otherwise by the user, all cabinets shall be constructed of cold-rolled carbon steel with the minimum sheet metal thickness, based on the overall outside cabinet dimensions with doors closed, as shown in Table 1. Table 1 —Sheet metal thickness requirements Length Height Minimum sheet metal thickness Not greater than 762 mm (30 in), and Not greater than 762 mm (30 in) 1.51 mm (0.0598 in or 16 gauge) Greater than 762 mm (30 in) but not greater than 1524 mm (60 in), or Greater than 762 mm (30 in) but not greater than 1219 mm (48 in) 1.90 mm (0.0747 in or 14 gauge) Greater than 1524 mm (60 in), or Greater than 1219 mm (48 in) 2.67 mm (0.105 in or 12 gauge) Note that the minimum sheet metal thickness shall apply if either the length or the height, or both length and height, fall within the dimensional range for that sheet metal thickness. For example, a cabinet with a length of 700 mm and a height of 700 mm would require a minimum 1.51 mm sheet metal thickness. A cabinet with a length of 700 mm and a height of 800 mm would require a minimum 1.9 mm sheet metal thickness (see Table 1). For special environmental applications where carbon steel cabinets are not suitable, either the environmental conditions or other materials, such as stainless steel, aluminum, polymeric, or special coatings, must be specified by the user. 5.5 Compartment styles and welding Unless specified otherwise by the user or chosen by the control cabinet designer, cabinets shall have a single compartment with one or two doors. If user specifications require isolated cabinet sections, or if the control cabinet designer chooses to provide isolated sections, cabinets may be constructed with internal compartments separated by steel barriers, with doors for each compartment. All external metal joints and seams shall be fully welded to prevent trapped water and corrosion. Intermittent welds on internal metal joints are acceptable, provided the metal surface preparation and finish coatings protect exposed metal from corrosion. 5 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers 5.6 Rain sheds The cabinet shall be constructed to minimize the ingress of water from the cabinet top when the doors are opened. Acceptable solutions include a sloped cabinet top or shield above the cabinet top to shed rainwater away from the doors toward the back of the cabinet, or a water guard or barrier fitted to the front edge of the cover or doorways. 5.7 Fixed back and side panels To minimize the number of penetrations through the cabinet shell, controls components shall not be mounted directly to the inner surfaces of the cabinet. Components shall be mounted on rigid steel panels with a thickness not less than the cabinet material thickness that are attached to and spaced a minimum of 12 mm (0.5 in) from the inner side or back walls of the cabinet. Openings and holes in the fixed panels shall be suitable for the secure mounting of components such as relays, components, terminals, and DIN rail. 5.8 Swing panels If additional panel surface is needed for mounting controls components, or if components need to be mounted on a panel inside the cabinet, swing panels may be used. Swing panels are flat steel panels vertically hinged and attached to the inside walls of the cabinet. With the external door of the cabinet open, the swing panel, complete with its mounted components, shall be capable of being opened through the main door opening to allow access to the fixed panels inside the cabinet. Swing panels shall have latching mechanisms to secure the panel in the closed position. Swing panels shall be capable of being opened a minimum of 90 degrees and be equipped with a mechanism to secure the panel in the open position. All exposed energized terminals rated for a potential Vac > 150 V or Vdc > 48 V on the back side of swing panel shall be fully protected with a removable, fire-retardant, transparent shield, or other means, to minimize the risk of accidental contact. 5.9 Doors, hardware, and gaskets Cabinets shall be equipped with vertically hinged doors consisting of two or more hinges, or a piano hinge, and be capable of opening a minimum of 90 degrees. If the hinges are mild steel, all exposed edges shall be completely welded to the door and cabinet to provide a full-weather seal. The doors shall be equipped with corrosion-resistant handled latching mechanisms that secure the door to the cabinet at two or more points. A combination of a handle and door clamps may be used for small control cabinets. The handles or doors shall be suitable to be locked with a padlock fitting the dimensions listed in Figure 1. Unless specified otherwise, door handles shall not be equipped with integral key locks. Dimension A B C D E mm 11 50 29 51 51 in 0.4 1.9 1.2 2.0 2.0 Figure 1 —Minimum padlock dimensions 6 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers Each door shall be equipped with a mechanism to secure the door at a minimum 90 degree open position. The inner surface of one door shall be equipped with one or more sufficiently sized and constructed pockets to hold the transformer manuals and other documents. Unless approved by the user, pockets for the manuals and other documents shall be constructed with the same material as the cabinet, but the material thickness of the pocket may be thinner, provided it is sufficient to support the manual and documents. Doors shall have a gasket system that meets NEMA 250 requirements. The gasket material shall be durable, suitable for the in-service environment, and replaceable. Viewing windows, if provided in doors, shall meet the requirements of the cabinet’s NEMA designation. All external bolting hardware shall be stainless steel or nonferrous metal. 5.10 Ventilation and drains Each cabinet compartment shall be equipped with at least one ventilator. The ventilator shall be located near the top of the cabinet wall or on the cabinet door. Additional ventilators may be required to maintain the temperature range in 5.22. The bottom of the cabinet shall have a 12 mm (0.5 in) minimum diameter drain hole located at the lowest level of the cabinet bottom in the event that water enters the cabinet. Ventilators and drains shall be screened to prevent intrusion by insects. 5.11 Location of conduit entry points Conduits for leads from the transformer components shall only enter through the sides of the control cabinet. The cabinet design shall have sufficient space at the lead entry points and not interfere with the side panels. Conduit fittings shall be rated NEMA Type 4. 5.12 Bottom plate for cable entrance Each compartment of the cabinet that will have external cables connected to substation circuits shall have an opening in the compartment bottom. The opening size shall be suitable to accommodate incoming control cable conduits, or as per dimensions specified by the user. This opening shall be covered with a plate that is gasketed and bolted to the underside of the cabinet. The plate may be constructed with the same material as the cabinet or with aluminum. If aluminum plate is used, it should be approximately 3 mm (0.12 in) thick. The plate facilitates the cutting of openings for the substation conduits during site installation. The cabinet design shall allow sufficient space above the bottom plate to facilitate the routing of the external cables to the terminal blocks. 5.13 Grounding of panels and doors Fixed panels, swing panels, and doors shall be intentionally grounded to the cabinet body with a flexible ground strap. 7 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers 5.14 Finish coatings Painting is not required for specialty cabinets made from stainless steel, aluminum, or polymer unless specified by the user. Cabinets made from carbon steel require painting. The metal surfaces shall be suitably prepared for painting by shot blasting or chemical etching processes. The paint process shall be epoxy paint, silicone-alkyd paint, or powder coat. The same paint and process as used for the transformer may also be selected. The combined primer and finish coat dry-film thickness shall be minimum 0.127 mm (0.005 in or 5 mils). Unless specified otherwise, the exterior color shall be ANSI 70 gray, as specified in ANSI Z55.1, and the interior color shall be white or gray. 5.15 External cabinet grounding and grounding terminals Each cabinet or cabinet section that is connected to another section by bolts or screws shall be equipped with one or more external NEMA-standard two-hole ground pads welded to the bottom or lower side of the cabinet or, alternately, with a 12 mm or ½-in threaded stainless-steel stud welded to the cabinet wall with stainlesssteel fastener hardware. This requirement is to ensure a continuous low-impedance electrical path from each device ground point or terminal to the external ground pad for any ground current. The cabinet grounding pad(s) shall consist of a copper-faced steel pad or a stainless-steel pad without copper facing, 50.8 mm × 88.9 mm (2 in × 3½ in), with two holes horizontally spaced on 44.5-mm (1¾ in) centers and drilled and tapped for ½ in -13 Unified National Coarse (UNC) thread, as defined in ANSI B1.1. Minimum thickness of the copper facing shall be 0.4 mm (0.016 in). Minimum threaded depth of the holes shall be 12.7 mm (½ in). Thread protection for the ground pad shall be provided. 5.16 General cabinet layout In general, one-door and two-door cabinets shall be organized in an orderly and logical manner to minimize the risk of wiring errors. All secondary wiring for any current transformer shall be connected to the same terminal block and not divided among multiple terminal blocks. Stacks of DIN rail terminals shall be equipped with dividers or installed with spaces between terminals for each current transformer and connected in the same manner. To the extent practical within the available cabinet dimensions, current transformer terminal blocks should be arranged with all current transformers for each phase in a common row or column. Current transformer terminal blocks shall also be grouped by location and function and arranged within each group by stacking order. Cooling control, alarm, and trip-circuit terminal blocks that provide the user’s connections shall be arranged in a vertical or rectangular configuration similar to the general layout examples shown in Figure A.3. Terminal block and test-switch locations shall provide adequate room between groups of columns of terminal blocks for orderly wire routing, troubleshooting, and any user’s cable routing and connections. The user or supplier may provide a standard layout design that meets these requirements, or the cabinet layout may be organized with the locations and minimum dimensions as shown on Figure A.1, Figure A.2, and Figure A.3. Cabinet areas in the figures are approximate and can be expanded or contracted to accommodate the terminals and devices in any particular cabinet. Terminals and devices may be added or deleted as required. 8 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers 5.17 Internal ground connections and ground bus 5.17.1 General The cabinet section shall be equipped with one or more internal NEMA-standard two-hole ground pads, with the same specifications as the external grounding pad described in 5.15, or stainless-steel studs welded to the cabinet wall with stainless-steel fastener hardware in each cabinet section equipped with a ground bus, to provide positive electrical connection to the ground bus bar. If a ground pad is used, it shall be copper-faced steel or stainless steel without copper facing. Thread protection shall be provided for the ground pad. If a stainless-steel stud is used, it shall be free of paint or any other coating that changes the electrical properties of the stainless steel. 5.17.2 Design The ground bus shall be a tin-plated copper bar at least 25 mm high and 6 mm thick with adequate length to accommodate the required terminals. Each separate section of the cabinet containing circuits or electrical equipment shall be equipped with one, or more if required, ground bus bar. The bus shall be solidly connected to a ground pad or stud inside the cabinet, either directly or with uninsulated copper cable or copper cable insulated with transparent dielectric material. If a ground cable is required, it shall be at least 21.1 mm2 (AWG 4) or a conductor with equivalent cross-sectional area. The ground bus shall be drilled and tapped with a #1032 female thread for connection of circuit grounds, including accessories external to the cabinet. 5.17.3 Mounting The ground bus shall be mounted within 150 mm (5.9 in) of the bottom of the cabinet on, or adjacent to, the back panel. 5.18 Lights and ac power outlet Each cabinet shall be equipped with an internal incandescent or compact fluorescent light fixture with a minimum rating of 60 W for incandescent lights or 800 lumens for all other types. The light fixture shall accommodate a standard 26 mm, E26 base lightbulb. The light shall be controlled by a switch on the door for that section of the cabinet that automatically turns the light on when the door is opened and off when the door is closed. The cabinet may be ordered with an optional dual GFI 110–120 V single-phase power outlet. The ground connection for the GFI outlet shall be completely isolated from the ground bus in the cabinet and shall be connected only to a separate ground location to protect from inadvertent relay operations. The outlet shall be located in an accessible location inside the cabinet or outside using a weather-proof enclosure. 5.19 Wiring Wires that terminate on screw or stud connectors shall be terminated with crimped, ring-type lugs with not more than two wires connected to any terminal screw or stud. Lug collars may be bare or insulated. Terminals on components that do not accommodate any type of lug may require bare wire connections. Wires shall be continuous between lugs without splices. The standard wiring between terminals or devices inside the control cabinet, other than heaters, shall be stranded, single conductor, copper, 600 V wire with strand count not less than Class C. The wire shall be SIS 9 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers type or ETFE/FEP or MTW type if a higher operating temperature range or oil resistance is desired. All insulated ground wires shall be stranded, single conductor copper with green-colored insulation except the connections between the internal ground busses and cabinet ground terminals, as described in 5.17.2. All wire sizes shall be selected in accordance with the NEC and with the following minimum wire sizes: ⎯ All ground wires from terminals or devices connecting to the ground bus inside the cabinet shall be 3.31 mm2 (AWG 12) minimum. ⎯ All current transformer circuit wiring shall be 3.31 mm2 (AWG 12) minimum. ⎯ All other circuit wiring, with the exception of low-voltage signal conductors, shall be 2.08 mm2 (AWG 14) minimum. These requirements do not apply to internal component wiring for devices inside the cabinet such as meters, annunciators, or other similar equipment, but the cabinet designer must ensure that such devices are adequately rated for expected service conditions. 5.20 Circuit protection 5.20.1 General Circuit breakers shall be used to protect all ac power circuits. Fuses may be used to protect dc circuits when the maximum current is limited to 5 A or less, or if fuses are recommended by the original equipment manufacturer (OEM) to protect their devices. All other dc circuits shall be protected by dc circuit breakers. All fuses and fuse holders shall have a voltage rating equal to or greater than the dc source voltage. Alternating current power circuit breakers shall be single-phase or three-phase, as required. Direct current breakers shall be single-pole type. All circuit breakers shall have a voltage rating equal to or greater than the supply voltage. Plug-in circuit breakers may not be used. Unless specified otherwise, breakers shall be magnetic or thermal/magnetic type. Thermal/magnetic-type breakers shall properly perform their intended short-circuit overcurrent and overload protection functions under the ambient temperature range of the cabinet when the transformer is in-service. If ambient temperatures in the control cabinet exceed the rated temperature range for a thermal/magnetic breaker, the breaker must be derated in accordance with the breaker manufacturer’s instructions. If, after derating, the breaker cannot provide overcurrent and overload protection coordination to the circuit over the entire ambient temperature range of the control cabinet, a magnetic-type breaker with separate overload protection may be required. Branch circuits shall be designed in accordance with the NEC so that a fault in any branch circuit will result in the de-energization of only the faulted branch circuit. All branch circuits shall be protected by a main circuit breaker. 5.20.2 Mounting and orientation Circuit breakers mounted directly to a panel shall be oriented vertically with the input on the top and the output on the bottom. DIN rail–type circuit breakers shall also be mounted vertically, with input on top and output on the bottom, with the DIN rails oriented horizontally. Fuses shall be installed in fuse holders and the fuse holders shall be mounted on a panel in a location with free and clear access when all doors are open. 10 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers 5.21 Contactors 5.21.1 General Contactors shall be single-phase or three-phase 600 V closed-face type to match the standard or specified supply voltage. 5.21.2 Mounting Contactors shall be mounted on the back panel or on a swing panel. 5.21.3 Orientation Contactors mounted directly to a panel shall be oriented vertically with the input on the top and the output on the bottom. DIN-rail−type contactors shall also be mounted vertically, with input on top and output on the bottom, with the DIN rails oriented horizontally. 5.22 Heaters 5.22.1 General Unless specified otherwise, the control cabinet shall be provided with one or more ac-powered heaters per cabinet section to prevent condensation. If resistive-type heaters are used, they shall be controlled with a thermostat. If PTC-type heaters are provided, the thermostat may not be required. Unless specified otherwise, the heaters shall be sized to maintain a 0 °C minimum, 40 °C maximum cabinet temperature over the specified operating conditions ambient temperature range. All components in the cabinet shall be sufficiently rated to operate within the same rated temperature range as the cabinet. Heaters shall be wired with high temperature wire suitable to withstand up to 150 °C. 5.22.2 Mounting The heaters should be mounted on the bottom of the cabinet or lowest part of the back panel or side walls, placed away from the doors and cable entrance plate and wiring, and covered with protective guards to minimize the risk of damage or injury to components, cables, or personnel from accidental touch. 5.22.3 Orientation Heaters shall be oriented so the wiring is not located above the heating surface. 5.23 AC power and cooling control circuits Unless alternate circuit designs are specified, the ac power, auxiliary power, and cooling control circuits shall be configured as shown in the appropriate cooling control schematic drawings in Annex A. 11 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers The cooling control drawings in Annex A are intended to show how various options shall be connected within the circuits. All of the options that are shown in the drawings are shown for ONAN/ONAF/ONAF or ONAN/OFAF/OFAF cooling, but shall also be connected as shown when specified for OFAF/OFAF or ODAF/ODAF cooling designs. Other optional devices within the cooling control circuit that are specified but not listed in this Standard shall be connected as specified by the user, or if not specified, as designed by the control cabinet designer. Lights and heaters are shown on the cooling control drawings connected to one common circuit breaker. If desired by the control cabinet designer or specified by the user separate circuit breakers may be provided for the heaters and lights. 6. Numbering and labeling system 6.1 Device numbers Devices shall be numbered on drawings and wire markers in accordance with IEEE Std C37.2. 6.2 Current transformer numbering Current transformers (CTs) shall be numbered in accordance with the conventions specified below. In general, the current transformer numbering system shall provide a clear identification of the type, general location, winding, phase, and position of each current transformer whose secondary wiring is terminated in the control cabinet. The current transformer numbering system shall be consistent with the numbering used to identify current transformers on the transformer nameplate and/or current transformer nameplate. The following numbering system is recommended if an alternate numbering system that meets these requirements is not specified by the user or in standard use by the supplier. General designation = (General location)(Type)-(Winding)(Phase)-(Position) where (General location) = Blank or no designation for internal bushing current transformers I, for internal CTs that are not bushing mounted XX, for all external CTs (Type) = CT, for relay and metering functions WCT, for winding temperature gauge functions XCT, for LTC control or other load sensing functions (Winding) = H, to indicate the HV windings X, to indicate the XV windings Y, to indicate the YV windings 12 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers (Phase) = 1, to indicate phase #1 2, to indicate phase #2 3, to indicate phase #3 0, to indicate the neutral position Note that an autotransformer neutral position is designated H0X0. (CT position) = 1, 2, 3, 4, etc., with 1 being the innermost CT of each designation, and the highest number being the outermost CT. The innermost CT is defined as the CT in a group of CTs that is located closest to the transformer winding. The outermost CT is defined as the CT that is located farthest from the winding. If only one CT is located on a bushing or in an internal interwinding location, it shall be numbered as 1. Internal, not bushing-mounted CTs shall also include the letter P before the position number to indicate that the CT is located on the polarity end of a winding or the letter N before the position number to indicate that the CT is located on the nonpolarity end of a winding. For example, P1, P2 or N1, N2, N3, etc. See Figure A.11 for several examples of this numbering system. 6.3 Terminal block, device, and terminal labels Terminal blocks shall all be labeled with the appropriate designations, using a plate or tag permanently attached to the back or side panels above or adjacent to each vertically mounted terminal block or to the left of each horizontally mounted terminal block. Devices located inside the control cabinet shall be labeled with the appropriate designation, listed in 6.4, 6.5, and 6.6, using a plate or tag permanently attached above, below, or adjacent to, the device where the view of the plate or tag will not be obstructed by wiring or components. 6.4 Current transformer circuit terminal block, terminal, test switch, and secondary wiring numbers The following numbering systems for terminal blocks, terminals, component, and wires shall be used on all drawings, nameplates, terminal block labels, and wire markers unless an alternate numbering system is specified by the user. In general, each current transformer terminal block or set of DIN rail-mounted current transformer terminals, terminals, and test switch shall be numbered with the same current transformer designations, as described in 6.2 for the current transformer connected to that terminal block or set of DIN rail-mounted terminals, terminal, or test switch. The following numbering system is recommended if an alternate numbering system that meets these requirements is not specified by the user or in standard use by the supplier. Current transformer terminal block terminals shall be numbered with the terminal block number plus the terminal number, or: CT-(Winding)(Phase)-(CT position)-(Terminal Number) Or, if the CT is used for winding temperature, it shall be numbered as follows: WTCT-(Winding)(Phase)-(CT position)-(Terminal Number) 13 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers where (Winding), (Phase), and (CT position) are defined above (Terminal Number) = 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 with terminal number 1 located at the top of vertical terminal blocks or the left of horizontal terminal blocks For example, the terminal block for the innermost CT on the X2 bushing would be numbered CT-X2-1. The top terminal on this terminal block would be numbered CT-X2-1-1. Current transformer wiring terminal blocks shall be located and connected as shown in Figure A.9. The CT circuits with sliding link terminals shall be connected as shown in Figure A.10. Current transformer test switches and test-switch terminals, when supplied, shall be numbered as follows: TS-(X)-(Terminal Number) where (X) = 1, 2, 3, etc. (Terminal Number) = 1, 2, 3, etc., or in agreement with the terminal numbers identified by the testswitch manufacturer and marked on the test switch Unless specified otherwise by the user, all current transformers connected to vertically mounted terminal blocks or test switches shall be connected with the polarity wires connected above the nonpolarity wires. Unless specified otherwise, if horizontally mounted terminal blocks or test switches are provided, the polarity wires shall be connected to the left of the nonpolarity wires. Current transformer secondary wiring shall be numbered X1, X2, X3, for example, in accordance with IEEE Std C57.13™.10 The complete CT secondary wire number shall be the current transformer number plus the secondary wiring number, or: (Winding)(Phase)-(CT position)-(secondary wire number) 6.5 Control, alarm, and trip-circuit terminal blocks and terminal numbers Circuits shall be provided in the control cabinet for all standard accessories with electrical circuitry as listed in IEEE Std C57.12.10 and all additional electrical accessories provided with the transformer. The following numbering system is recommended if an alternate numbering system that meets these requirements is not specified by the user or in standard use by the supplier. Control, alarm, and trip-circuit wiring terminal blocks shall be labeled TB-(X),where X represents either X = A, B, C, D, etc. or X = 1, 2, 3, 4, etc. If the A, B, C system is used and more than 26 terminal blocks are required, the next three blocks after TB-(Z) should be labeled TB-(AA), TB-(AB), and TB-(AC), and subsequent terminal blocks should follow the same pattern. Terminals should be designated in order from left to right then down to the next rows of terminal blocks as illustrated on Figure A.3. Additional control, trip, and alarm circuit terminals that are required by the control cabinet design shall be grouped with those shown on the drawing and numbered in a consistent order following those terminals TB-A through TB-F as shown on Figure A.3. 10 IEEE Std C57.13, IEEE Standard Requirements for Instrument Transformers. 14 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers Device terminals shall be numbered in accordance with the following system: (Device Number)-(Device Terminal Number) where (Device Number) = the device number in accordance with IEEE Std C37.2 (Device Terminal Number) = agreement with the terminal numbers identified by the device manufacturer and as marked on the device. If a device contains terminal strips or blocks, the device’s terminal strip or block designation shall be included with the device terminal number Ground and ground bus terminals shall all commonly be designated as GND. 6.6 Wire markers Unless specified otherwise by the user, each wire terminating from a device on the transformer or in the control cabinet, or from another terminal in the control cabinet, or from another cabinet on the transformer shall be numbered and labeled in accordance with the following system: (Remote End Terminal Number) (< or >) (Local End Terminal Number) where (Remote End Terminal Number) = the terminal block or device number and terminal or device terminal number at the opposite end of the terminated wire (< or >) = the direction toward the opposite end of the terminated wire or toward the remote end terminal. On vertically mounted terminal block terminals, for example, this will be < on all wires terminated on the left side of the terminal and > on all wires terminated on the right side of the terminal. This will also be > on all wires connected to device terminals at the device end of the wire. (Local End Terminal Number) = the terminal block or device number and terminal or device terminal number at the location where the wire is terminated adjacent to the wire marker. Device 26 A3 26-A3 > TB-B-3 A2 26-A2 > TB-B-2 A1 26-A1 > TB-B-1 TB-A 1 2 TB-B 1 2 TB-B-1 > 26-A1 TB-B-2 > 26-A2 3 3 TB-B-3 > 26-A3 4 4 TB-A-1 > TB-B-1 TB-A-1 < TB-B-1 TB-A-2 > TB-B-2 TB-A-2 < TB-B-2 Figure 2 —Wire markers 15 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers 6.7 Wiring diagrams The user must specify which type of wiring diagram is required from the cabinet manufacturer if the user requires any type other than the manufacturer’s standard diagrams. The choice of wiring terminal destination tables, schematic drawings, point-to-point wiring drawings, or other systems may be provided. 7. Cabinet construction options 7.1 General The following optional cabinet construction requirements shall be specified using the Sample Ordering Form in Annex B or an equivalent form. 7.1.1 Option A: NEMA or IEC performance requirements If not specified, cabinets shall meet or exceed the performance requirements of NEMA 3R for outdoor use with natural ventilation. Other NEMA or IEC designations may be specified for indoor locations or service in corrosive or combustible dust environments. Note that standard layouts and spacings in this document may not be practical with some NEMA-Type cabinets for special environments and, in these cases, the supplier shall discuss the issues with the user and the user and supplier may agree on other acceptable designs. NEMA-Type performance requirements are defined in NEMA 250. 7.2 Option B: Sheet metal thickness If not specified, the control cabinet shall be constructed of sheet metal in accordance with the thickness requirements listed in 5.4 and 5.2. Other metal thicknesses, including 3.0 mm (0.118 in) (or 11 gauge), may be specified by dimension or gauge number. 7.3 Option C: AC power and dc relay voltages If not specified, the control cabinet shall be designed for a 120 V single-phase supply voltage for cooling, lights, heaters, and similar loads. Other single-phase, three-phase, or other ac supply voltages may be specified. If not specified, the control cabinet shall be designed for a 125 V relay and alarm dc voltage. Other dc voltages for alarm, trip, and component power may be specified. 16 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers 7.4 Option D: Terminals, terminal blocks, wire raceways, and wire bundling 7.4.1 General Unless specified otherwise, control cabinets shall be supplied with standard wiring terminal blocks, standard current transformer terminal blocks when the transformer is equipped with one or more current transformers and with power terminal blocks when forced air and/or forced oil cooling are provided. Control cabinets may be specified with optional sliding link terminal blocks for wiring and/or current transformer circuits. Control cabinets may be specified with optional test switches for current transformer circuits. 7.4.2 Standard terminal blocks Standard terminal blocks shall be surface mount or DIN rail mount–type and constructed in one piece with self extinguishing material in groups of 6, 10, or 12, as required, with fixed terminals. The terminals shall be continuously rated for not less than 600 V ac, with a sufficient continuous amperage rating for all attached circuits under maximum current conditions, such as locked rotor current. Terminals shall be furnished with washerless binding screws or studs designed for attaching ring lug crimped wires with wire sizes as small as 1.3 mm2 (AWG 16) to as large as 5.3 mm2 (AWG 10). Screw or stud size shall be not less than 5 mm, M5 as listed in ISO 262 (the equivalent ANSI nonmetric screw or stud size is #10). The #10-size terminals shall be #10-32. 7.4.3 Standard current transformer terminal blocks Standard current transformer terminal blocks shall be of the same general construction as standard terminal blocks and equipped with a shorting bar that permits each terminal to be shorted (or connected) to the others when a set screw is inserted. 7.4.4 Power terminal blocks Power terminal blocks shall be in groups of three for single-phase supply voltage and in groups of four for three-phase power supplies. They shall be rated at 600 V and 100 A or 2.0 times the auxiliary power voltage and 2.0 times the maximum total auxiliary power load current. Power terminal blocks shall be located on the lower back wall approximately 300 mm (11.8 in) above the cable entrance plate on the cabinet bottom so that power cables can enter the cabinet and connect to the terminals without requiring sharp bending. Power terminal blocks shall be equipped with protective covers to minimize the risk of accidental user contact with the energized terminals. If the control cabinet is supplied with an automatic transfer switch, or provisions for an automatic transfer switch, two sets of power terminal blocks are required. The power terminal blocks shall be separated by not less than 150 mm (5.9 in) to accommodate the routing of the normal and emergency power cables in two separate conduits into the bottom cable entrance plate of the control cabinet. 7.4.5 Optional sliding link terminal blocks Sliding link terminal blocks, when ordered, shall be of the same general construction as standard terminal blocks, with the exception that each terminal can be opened or closed by means of a securing screw that can be loosened and slid into the open or closed position then tightened to remain securely in place. 17 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers 7.4.6 Optional current transformer test-switch blocks Current transformer test-switch blocks, if ordered, shall be equipped with a knife switch for each test terminal which, when opened, permits a test plug to be inserted between the circuit terminals without opening the CT circuit. The test-switch terminal block can be supplied to provide one or two test terminal switches for each CT. If only one test switch is provided, it shall be on the wire connecting to the polarity terminal of the CT. If test switches are located on a swing panel, with the test terminals located on the outside of the swing panel, the CT circuits can be grouped at the discretion of the control cabinet designer, provided all terminals are designated with engraved or printed plates as described in 7.4.7 and each twowire pair for each CT is terminated adjacent to each other and on one test-switch terminal block. 7.4.6.1 Mounting All terminal blocks, other than power terminal blocks, can be either mounted directly to the back panel of the cabinet, onto the inside of a swing panel, or mounted on DIN rails. 7.4.6.2 Orientation Standard terminal blocks and standard current transformer terminal blocks shall be oriented with the terminals stacked in a vertical group, with the two sides of each terminal located on the left and right. Power terminal blocks shall be oriented with the terminals stacked in a horizontal group with the two sides of each terminal located on the top and bottom. 7.4.7 Terminal block designations Unless specified otherwise by the purchaser, terminal blocks shall be designated with the alphanumeric identifiers listed in Clause 6. Terminal designations shall be labeled using engraved or printed 25 mm × 25 mm (1 in × 1 in) (minimum) plates. Plates may be plastic or phenolic or, if specified by the user, stainless steel. Plates constructed of plastic or phenolic material shall be white with black letters or black with white letters. Stainless-steel plates shall be bare metal or painted white with black letters. 7.4.7.1 Terminal designations on terminal blocks Unless specified otherwise by the purchaser, terminals on terminal blocks shall be designated as 1, 2, 3, etc. on the terminal block and with the terminal block designation followed by a dash ( - ) and numbered from top to bottom or left to right on drawings or wire markers. For example, the top terminal on a vertically oriented terminal block, Terminal Block TB-B, shall be designated as TB-B-1 on drawings and wire markers. 7.4.8 Wire bundling and optional wire raceways Optional wire raceways shall be provided when specified or if preferred by the cabinet manufacturer. If raceways are not provided, all wiring shall be secured into orderly groups of bundles with cable ties or similar materials that will not damage the wiring and will facilitate component replacement or disconnection, if needed. If wires are grouped into bundles for routing within the cabinet, all such bundles shall be subjected to the following requirements. Wire bundles may not contain more than one type of the following circuits in any bundle and all bundles shall be sufficiently isolated so that undesired voltages or currents are not induced in other bundles: 18 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers ⎯ Current transformer secondary current circuits ⎯ AC power circuits ⎯ DC relay and low-voltage signal circuits ⎯ Bushing potential device secondary circuits Wire bundles that route wiring to a door or swing panel shall have sufficient slack and protective covering to prevent damage to any of the wires from rubbing against the cabinet or panel when the door or swing panel is opened or closed. 7.5 Option E: Cooling control switches 7.5.1 General When the transformer is equipped with any type of forced cooling, the cooling circuit shall be equipped with cooling control switches to facilitate maintenance and testing. Switches shall be sufficiently rated for the required control voltage and maximum continuous and short time current required for all components on the circuit being switched. 7.5.2 Auto/Off/Manual switch The Auto/Off/Manual switch allows the operator to switch the cooling control from either automatic operation or manual operation, or to switch all cooling off. In automatic operation, cooling operation is switched on or off by oil and/or winding temperature gauges. In manual operation, cooling is switched on or off by the Auto/Off/Manual switch. This switch may be eliminated if the transformer is equipped with an electronic temperature gauge/cooling controller that can perform the same functions. 7.5.3 Lead stage selector switch The lead stage selector switch allows the operator to switch the order of temperature controlled cooling group operation. This switch can be eliminated when the transformer is equipped with an electronic temperature gauge/cooling controller that can be programmed to perform the same functions as the switch. 7.5.4 Optional manual stage selector switch The manual stage selector switch is optional and permits the operator to switch on cooling stage 1, cooling stage 2, or cooling stages 1 and 2 combined. This switch may be eliminated if the transformer is equipped with an electronic temperature gauge/cooling controller that can perform the same functions. 7.5.4.1 Mounting and orientation All switches shall be located side-by-side, with the faceplates and control handles facing outward. 19 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers 7.6 Option F: Annunciator 7.6.1 General Annunciators are not required unless specified. If an annunciator is specified, all annunciator alarm points shall be capable of being connected to either seal in the alarms or to close the alarm contacts when the alarm signal is present. The annunciator shall also be equipped with a light or other visual method for each alarm and a test switch to test the indication and alarm contacts and one form-C dry contact outputs. All lights or displays shall be sufficiently bright to be visible in full sun when lit. The annunciator make and model may be specified by the buyer or, otherwise, the control cabinet manufacturer may supply an annunciator supplied by an OEM or design and construct the annunciator circuit as an integral part of the control cabinet. 7.6.2 Ordering with the annunciator table and checklist The following data shall be specified by the buyer on the annunciator table and checklist (see B.2), or another equivalent form: ⎯ Position of each alarm light or annunciator indication on the annunciator display ⎯ Name of each alarm point ⎯ Seal-in function of each alarm ⎯ Color of each alarm light if individual indicator lights are used ⎯ If a window is required in the control cabinet door 7.7 Option G: Automatic transfer switch 7.7.1 General If the manufacturer, make, or model number of the automatic transfer switch is not specified, the control cabinet designer may design or supply an automatic transfer switch with voltage and current ratings suitable for the control cabinet circuit. If an automatic transfer switch is specified, the control cabinet shall be designed to be supplied with dual ac power supply terminals to provide auxiliary power to the transformer from two sources, a normal and an alternate supply. 7.7.2 Ratings The automatic transfer switch shall be rated for the specified operating voltage and with a continuous current rating greater than the maximum current with all devices on and all motors running, and shall also be sufficiently rated for an inrush current greater than the maximum inrush current with all devices on and all motors starting, as permitted by the control circuit. If an automatic transfer switch is specified, voltage and current ratings must also be specified by the user, but the current ratings shall be verified by the control cabinet designer, and if the specified current ratings are insufficient, the buyer shall be advised and a suitable alternative selected. If the automatic transfer switch is specified by manufacturer and model number, the control cabinet designer must also verify that the ratings are sufficient and advise the user if the ratings are not adequate. If the automatic transfer switch is not specified by 20 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers manufacturer or model number, the control cabinet designer may supply an automatic transfer switch supplied by an OEM or design and construct the automatic transfer switch circuit as an integral part of the control cabinet. 7.7.3 Operation The automatic transfer switch shall switch to the alternate supply after a short time delay upon loss of the normal supply and shall revert to the normal supply whenever it is available and after a short time delay. The automatic transfer switch shall be equipped with alarm contacts for loss of power for both the normal and the alternate power supplies. 7.7.4 Voltage surge arresters Unless specified otherwise, the automatic transfer switch is not required to be furnished with voltage surge arresters. 7.7.5 Mounting The automatic transfer switch shall be mounted on the back or side panel and separated from the other components. 7.7.6 Orientation The orientation of the automatic transfer switch shall be in accordance with the automatic transfer switch component or manufacturer’s requirements. 7.8 Option H: Dead-front cabinet design If specified to provide an optional dead-front design, control cabinets will be constructed with all energized terminals enclosed inside the cabinet behind one or more secondary panel doors inside the exterior cabinet door(s). The secondary panel doors may be equipped with switch handles, pushbuttons, indicating lights, or other types of indicating targets or semaphores, meters, or displays, provided all such devices have no energized terminals or parts exposed on the outside of the secondary panel door(s). Dead-front design secondary panel doors shall extend from top to bottom and side to side inside the cabinet and effectively block access to all parts and components behind the panels. All such panels shall be equipped with provisions for padlocking the doors closed, using a padlock as large as that described in 5.9. 7.9 Option I: Visible air gap 7.9.1 General If not specified, a switch or device to provide a visible air gap in the ac or dc circuits shall not be required. If the requirement for one or more visible air gaps in the ac or dc circuits are specified, a knife switch, or similar device shall be provided to perform this function. The switch or device shall be located in an area where it can be easily accessed while standing on the ground at the front of the cabinet and shall be shielded by a protective cover to minimize the risk of accidental contact. The cover shall be designed to fit over the switch 21 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers to cover and secure it in both the open and closed positions. The switch handle shall be on the de-energized half of the open switch. If the requirement is specified, the user shall specify the number of switches or devices and the locations where a switch or device shall be located. If only one switch or device is specified, the circuit shall be equipped with one knife switch or device located in the circuit to energize or de-energize all devices and circuits in the control cabinet fed by the power source, except those terminals where the external cable is terminated and the wiring between those terminals and the switch or device. If multiple switches or devices are specified, the user must specify which circuits are to be equipped with a switch or device. The switch or device shall be rated for 600 V and not less than 125% of the maximum continuous or momentary current, and shall be two-pole for dc or single-phase ac circuits, and three-pole for three-phase ac circuits unless specified otherwise by the user. 22 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers Annex A (normative) Figures Figure A.1—CT terminal arrangement and user’s wiring locations 23 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers Figure A.2—CT terminal arrangement and user’s wiring locations with optional test switches 24 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers Figure A.3—Cooling control, alarm, and trip-circuit terminals general layout 25 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers Figure A.4—Standard cooling control schematic ONAN/ONAF/ONAF or ONAN/OFAF/OFAF cooling 26 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers Figure A.5—Standard cooling control schematic OFAF/OFAF or ODAF/ODAF cooling 27 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers AC Power Supply JUMPER – REMOVE FOR USER’S LOCKOUT 52 52 CPT 52 USER’S LOCKOUT 27 43 MAN 52 43 MAN 43 AUTO 43 AUTO 49-1 26-1 49-2 26-2 43C 1 43C 2 43C 2 43C 1 LIGHTS AND HEATERS 52 52 27 4-1 27 5 1 4-2 49T-1 Pumps and/or fans Stage 1 5 1-2 27CP 5 2 5 1-2 49T-2 Pumps and/or fans Stage 2 4-2 4-1 Notes: AC power supply circuit and components can be single-phase or three-phase, as required. Dotted line indicates a third phase. The control power circuit should be single-phase. Control Power Transformer (CPT) and circuit breaker on power supply side of CPT may not be required if the AC supply voltage can supply the required control voltage. User’s lockout contact and wiring should be provided by the user, if required, to shut down all cooling in the event of a transformer trip. The control circuitry should be delivered with the jumper installed and the jumper must be removed by the user if the lockout is used. The Supplier should set device 26 so contact 26-2 closes at a higher temperature than 26-1 and set device 49 so contact 49-2 closes at a higher temperature than 49-1. The contact actuation temperatures should be determined by the Supplier or User. DEVICE DESCRIPTION 4 5 26 27 27CP 43 43C 49 49T 52 CPT MAGNETIC CONTACTOR MANUAL STAGE SELECTOR SWITCH OIL TEMPERATURE RELAY UNDERVOLTAGE RELAY – TIME DELAY DROP OUT (TDDO) UNDERVOLTAGE RELAY – CONTROL POWER - TDDO AUTO/OFF/MANUAL SWITCH LEAD STAGE SELECTOR SWITCH WINDING TEMPERATURE RELAY THERMAL CUT-OUT CIRCUIT BREAKER CONTROL POWER TRANSFORMER COOLING CONTROL SCHEMATIC WITH OPTIONAL MANUAL STAGE SELECTOR SWITCH ONAN/ONAF/ONAF OR ONAN/OFAF/OFAF COOLING Figure A.6—Cooling control schematic with optional manual stage selector switch ONAN/ONAF/ONAF or ONAN/OFAF/OFAF cooling 28 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers AC Power Supply JUMPER – REMOVE FOR USER’S LOCKOUT 52 52 CPT 52 USER’S LOCKOUT 27 43 MAN 52 43 AUTO 43 MAN LIGHTS AND HEATERS 52 27CP 52 27 4-1 49/26E 27 5 1 4-2 49T-1 Pumps and/or fans Stage 1 5 1-2 5 2 5 1-2 49T-2 Pumps and/or fans Stage 2 4-2 4-1 Notes: AC power supply circuit and components can be single-phase or three-phase, as required. Dotted line indicates a third phase. The control power circuit shall be single-phase. Control Power Transformer (CPT) and circuit breaker on power supply side of CPT may not be required if the AC supply voltage can supply the required control voltage. User’s lockout contact and wiring should be provided by the user, if required, to shut down all cooling in the event of a transformer trip. The control circuitry should be delivered with the jumper installed and the jumper must be removed by the user if the lockout is used. The electronic oil and winding temperature controller 49/26E should provide not less than two output contacts, for switching cooling on and off at two different temperature levels, plus the required alarm contacts. The controller may combine the oil and winding temperatures together on 2 common contacts, as shown on this drawing, or provide 4 separate contacts, 2 for oil temperature and 2 for winding temperature. The controller should be capable of alternating the lower temperature and higher temperature output contacts on a programmed interval to provide the same function as the 43C switch. If this function is not available, the 43C switch shall be added to the circuit. The 49/26E contacts are shown as normally closed to indicate failsafe operation. When the electronic temperature controller is energized and operating normally, the contacts should be open for temperatures below the set points and closed for temperatures above the set points. When the device is de-energized, however, the contacts close . DEVICE 4 5 27 27CP 43 49/26E 49T 52 CPT DESCRIPTION MAGNETIC CONTACTOR MANUAL STAGE SELECTOR SWITCH UNDERVOLTAGE RELAY – TIME DELAY DROP OUT (TDDO) UNDERVOLTAGE RELAY – CONTROL POWER - TDDO AUTO/OFF/MANUAL SWITCH ELECTRONIC OIL & WINDING TEMPERATURE RELAY THERMAL CUT-OUT CIRCUIT BREAKER CONTROL POWER TRANSFORMER COOLING CONTROL SCHEMATIC WITH ELECTRONIC OIL & WINDING TEMPERATURE RELAY AND OPTIONAL MANUAL STAGE SELECTOR SWITCH ONAN/ONAF/ONAF OR ONAN/OFAF/OFAF COOLING Figure A.7—Cooling control schematic with electronic oil and winding temperature relay and optional manual stage selector switch ONAN/ONAF/ONAF or ONAN/OFAF/OFAF cooling 29 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers AC Power Supply Dashed line shown for 3-phase power supply 86 USER’S LOCKOUT USER CONNECTION 52 CPT 52ST SHUNT TRIP 52 27 43 MAN 52 43 AUTO 43 AUTO 49-1 26-1 49-2 26-2 43C 1 43C 2 43C 2 43C 1 43 MAN LIGHTS AND HEATERS 52 27CP 52 27 27 4-27-1 4-1 4-27-2 4-27-2 4-2 49T-1 Pumps and/or fans Stage 1 49T-2 4-27-1 Pumps and/or fans Stage 2 4-1 4-2 Notes: A fail-safe cooling control circuit should be considered when the user cannot respond to a loss of control power alarm within an acceptable time, or for transformers with oil pumps and without a natural oil flow (ON..) rating. AC power supply circuit and components can be single-phase or three-phase, as specified by the user. Dotted line indicates a third phase. The control power circuit shall be single-phase. Control Power Transformer (CPT) and circuit breaker on power supply side of CPT may not be required if the AC supply voltage can supply the required control voltage. The Supplier should set device 26 so contact 26-2 closes at a higher temperature than 26-1 and set device 49 so contact 49-2 closes at a higher temperature than 49-1. The contact actuation temperatures should be determined by the Supplier or User. The 52ST circuit breaker is supplied with a shunt trip coil for remote tripping. User’s lockout contact and wiring should be provided by the user, if required, to trip 52ST and shut down all cooling in the event of a transformer trip. The user should also provide the voltage to the lockout contact for activating the circuit breaker’s shunt trip. 4-27-1 and 4-27-2 contactors have normally closed contacts that close when control power voltage is off and the contactor coils are de-energized. This fail-safe circuit can be provided with an electronic oil and winding temperature controller as shown on the COOLING CONTROL SCHEMATIC WITH ELECTRONIC OIL & WINDING TEMPERATURE RELAY AND OPTIONAL MANUAL STAGE SELECTOR SWITCH drawing. The 49 and 26 contacts must be normally closed to provide fail-safe operation. DEVICE DESCRIPTION 4 4-27 26 27 27CP 43 43C 49 49T 52 52ST CPT MAGNETIC CONTACTOR CONTACTOR (WITH N.C. CONTACTS) OIL TEMPERATURE RELAY UNDERVOLTAGE RELAY – TIME DELAY DROP OUT (TDDO) UNDERVOLTAGE RELAY – CONTROL POWER - TDDO AUTO/OFF/MANUAL SWITCH LEAD STAGE SELECTOR SWITCH WINDING TEMPERATURE RELAY THERMAL CUT-OUT CIRCUIT BREAKER CIRCUIT BREAKER WITH SHUNT TRIP CONTROL POWER TRANSFORMER COOLING CONTROL SCHEMATIC WITH OPTIONAL FAIL-SAFE COOLING CONTROL ONAN/ONAF/ONAF OR ONAN/OFAF/OFAF COOLING Figure A.8—Cooling control schematic with optional fail-safe cooling control ONAN/ONAF/ONAF or ONAN/OFAF/OFAF cooling 30 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers CT-H1-4-X1 CT-H1-4-X2 CT-H1-4-X3 CT-H1-4-X4 CT-H1-4-X5 CT-H1-4-X1 1 2 3 4 5 6 CT-H1-4-X2 User’s Connection CT-H1-4-X3 CT-H1-4-X4 NOTE: In general, fixed terminal CT terminal blocks must have the bottom terminal connected to the ground bus and an unused terminal between any two CT’s when multiple CT’s are connected to a terminal block. The examples in this drawing assume similar CT’s connected on each terminal block but 5-terminal and 3-terminal or 2-terminal CT’s may all be connected to a common terminal block provided these conditions are met. CT-H1-4-X5 CT-H2-4-X1 CT-H2-4-X2 CT-H2-4-X3 CT-H2-4-X4 CT-H2-4-X5 1 2 3 4 5 6 7 8 9 10 11 12 5 terminal CT configuration on 6 or 12 terminal terminal block CT-H1-4-X1 CT-H1-4-X2 CT-H1-4-X3 1 2 3 4 5 6 CT-H1-4-X1 1 2 CT-H1-4-X2 CT-H1-4-X3 3 4 5 CT-H2-4-X1 CT-H2-4-X2 6 7 CT-H2-4-X3 8 9 10 NOTE: This drawing shows all wiring from the current transformers connected on the left side of the terminal block and User’s connections on the right side, but CT and customer- side wiring shall be connected as shown in the CT Terminal Arrangement and User’s Wiring Locations drawing. CT-H1-4-X1 CT-H1-4-X2 CT-H1-4-X3 CT-H2-4-X1 CT-H2-4-X2 CT-H2-4-X3 CT-H3-4-X1 CT-H3-4-X2 CT-H3-4-X3 1 2 3 4 5 6 7 8 9 10 11 12 3 terminal CT configuration on 6, 10 or 12 terminal terminal block CT-H1-4-X1 CT-H1-4-X2 CT-H2-4-X1 CT-H2-4-X2 CT-H3-4-X1 CT-H3-4-X2 CT-H0-4-X1 CT-H0-4-X2 1 2 3 4 5 6 7 8 9 CT-H1-4-X1 1 2 3 4 CT-H1-4-X2 CT-H2-4-X1 CT-H2-4-X2 5 6 7 8 CT-H3-4-X1 CT-H3-4-X2 9 10 10 11 12 CT-H1-4-X1 CT-H1-4-X2 CT-H2-4-X1 CT-H2-4-X2 1 2 3 4 5 6 2 terminal CT configuration on 12, 10 or 6 terminal terminal block CT CIRCUITS TERMINAL LAYOUT AND WIRING STANDARD TERMINALS Figure A.9—CT circuits terminal layout and wiring standard terminals 31 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers Figure A.10—CT circuits terminal layout and wiring sliding link terminals option 32 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers Figure A.11—CT numbering examples 33 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers Annex B (informative) Forms B.1 Sample ordering form B.1.1 General user-specified options Options Are optional mounting brackets required for gauges or other devices? (Refer to 5.2.) Are limiting dimensions specified for the control cabinet? (Refer to 5.3.) Are nonstandard materials required for the cabinet construction? (Refer to 5.4.) Are nonstandard door handles required? (Refer to 5.9.) Are bottom plate dimensions specified? (Refer to 5.12.) Is a nonstandard painting or paint color specified? (Refer to 5.14.) Are GFI outlets specified? (Refer to 5.18.) Are nonstandard circuit breakers specified? (Refer to 5.20.) Are nonstandard cabinet vents specified? (Refer to 5.22.) Are nonstandard heater temperature ranges or ambient temperature ranges specified? (Refer to 5.22.1.) Are nonstandard user-specified circuit designs required? (Refer to 5.18, 5.20, 5.21, and 5.22.) Are nonstandard optional control circuit components required? (Refer to 5.23.) Are nonstandard CT wiring circuit or terminal block configurations required? (Refer to 6.4.) Are separate circuit breakers for heaters and lights required? (Refer to 5.23.) Is a user-specified type of wiring diagram required? (Refer to 6.4.) Are user-defined terminal block designations required? (Refer to 7.4.7.) Are user-defined terminal designations required? (Refer to 7.4.7.1.) Are wire raceways required? (Refer to 7.4.8.) Are there other nonstandard requirements? (Specify.) Y/N Specify or Comments B.1.2 Option A: Cabinet construction Options Select Specify or Comments Standard: NEMA 3R Other (Specify.) 34 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers B.1.3 Option B: Sheet-metal thickness Options Standard: per 5.4 Other: 3.0 mm (0.118 in or 11 gauge) Other (Specify.) Select Specify or Comments Select Specify or Comments Y/N Specify or Comments Y/N Specify or Comments B.1.4 Option C: AC power supply and dc relay voltages Options AC Standard: 120 V ac, single phase AC Other (Specify.) DC Standard: 125 V dc DC Other (Specify.) B.1.5 Option D: Terminal blocks Options User-specified optional wiring terminals required? (Specify.) Are user-specified optional CT wiring terminals required? (Specify.) Are user-specified or approved alternate CT wiring terminal spacing required? (Specify.) Are user-specified optional test switches required? (Specify.) B.1.6 Option E: Cooling control switches Options Do not include the standard Auto/Off/Manual switch. Do not include the standard manual stage selector switch. Supply optional lead stage selector switch? B.1.7 Option F: Annunciator Options Y/N Supply optional annunciator? Specify or Comments (Attach the annunciator table and checklist, B.2, if equipped.) B.1.8 Option G: Automatic transfer switch Options Supply optional automatic transfer switch? Are user-specified voltage and current ratings provided? Are user-specified manufacturer and model required? Supply optional lightning arresters? Are user-specified arrester ratings required? Y/N/n/a Specify or Comments 35 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply. IEEE Std C57.148-2011 IEEE Standard for Control Cabinets for Power Transformers B.1.9 Option H: Dead-front design Options Supply optional dead-front design? Y/N Specify or Comments Y/N Specify or Comments B.1.10 Option I: Visible air gap Options Supply optional single switch on ac power supply circuit? Supply optional single switch on dc circuit? Supply optional multiple switches? (Specify locations.) B.2 Annunciator table and checklist Annunciator manufacturer Model number Number of alarm points Supply voltage Window required in cabinet door (Y/N)? If Yes, specify size and location. Position Alarm Name Seal-in (Y/N) Light Color (if required) 36 Copyright © 2012 IEEE. All rights reserved. Authorized licensed use limited to: ABB Power Grids. Downloaded on March 02,2021 at 12:21:42 UTC from IEEE Xplore. Restrictions apply.