NEMA SG 11-2013 Guide for Handling and Maintenance of Alternating Current Outdoor High-Voltage Circuit Breakers.pdf

1、NEMA Standards PublicationNational Electrical Manufacturers AssociationNEMA SG 11-2013Guide for Handling and Maintenance of Alternating Current Outdoor High-Voltage Circuit BreakersNEMA SG 11-2013 Guide for Handling and Maintenance of Alternating Current Outdoor High-Voltage Circuit Breakers Publish

2、ed by: National Electrical Manufacturers Association 1300 North 17th Street, Suite 900 Rosslyn, Virginia 22209 www.nema.org Copyright 2013 by the National Electrical Manufacturers Association. All rights including translation into other languages, reserved under the Universal Copyright Convention, t

3、he Berne Convention for the Protection of Literacy and Artistic Works, and the International Pan American Copyright Conventions. 2013 National Electrical Manufacturers Association NOTICE AND DISCLAIMER The information in this publication was considered technically sound by the consensus of persons e

4、ngaged in the development and approval of the document at the time it was developed. Consensus does not necessarily mean that there is unanimous agreement among every person participating in the development of this document. NEMA standards and guideline publications, of which the document contained

5、herein is one, are developed through a voluntary consensus standards development process. This process brings together volunteers and/or seeks out the views of persons who have an interest in the topic covered by this publication. While NEMA administers the process and establishes rules to promote f

6、airness in the development of consensus, it does not write the document and it does not independently test, evaluate, or verify the accuracy or completeness of any information or the soundness of any judgments contained in its standards and guideline publications. NEMA disclaims liability for any pe

7、rsonal injury, property, or other damages of any nature whatsoever, whether special, indirect, consequential, or compensatory, directly or indirectly resulting from the publication, use of, application, or reliance on this document. NEMA disclaims and makes no guaranty or warranty, express or implie

8、d, as to the accuracy or completeness of any information published herein, and disclaims and makes no warranty that the information in this document will fulfill any of your particular purposes or needs. NEMA does not undertake to guarantee the performance of any individual manufacturer or sellers p

9、roducts or services by virtue of this standard or guide. In publishing and making this document available, NEMA is not undertaking to render professional or other services for or on behalf of any person or entity, nor is NEMA undertaking to perform any duty owed by any person or entity to someone el

10、se. Anyone using this document should rely on his or her own independent judgment or, as appropriate, seek the advice of a competent professional in determining the exercise of reasonable care in any given circumstances. Information and other standards on the topic covered by this publication may be

11、 available from other sources, which the user may wish to consult for additional views or information not covered by this publication. NEMA has no power, nor does it undertake to police or enforce compliance with the contents of this document. NEMA does not certify, test, or inspect products, design

12、s, or installations for safety or health purposes. Any certification or other statement of compliance with any health or safetyrelated information in this document shall not be attributable to NEMA and is solely the responsibility of the certifier or maker of the statement. SG 11-2013 Page i 2013 Na

13、tional Electrical Manufacturers Association CONTENTS Page Foreword . ii Section 1 SCOPE . 1 Section 2 SHIPMENT . 2 Section 3 STORAGE . 3 Section 4 UNPACKING . 4 Section 5 HANDLING 5 Section 6 SELECTION OF LOCATION FOR INSTALLATION 6 Section 7 MOUNTINGS . 7 7.1 Mounting in Cells 7 7.2 Mounting on Str

14、ucture 7 7.3 Floor Mounted 7 7.4 Bushings. 7 7.5 Operating Mechanism 8 7.6 Contacts . 8 7.7 Power Operating Circuit Breakers . Error! Bookmark not defined. Section 8 INSULATING FLUID 9 8.1 Oil Testing 9 8.2 Oil Drying 9 8.3 Filling Tanks with Oil 9 8.4 Filling and Handling De-energized SF6 Circuit B

15、reakers . 10 Section 9 CONNECTIONS . 12 9.1 High Voltage Connections 12 9.2 Secondary and Control Wiring Connections 12 9.3 Ground Connections 12 Section 10 AUXILIARIES 14 10.1 Tank Lifters . 14 10.2 Other Lifters 14 10.3 Undervoltage Trip Device . 14 10.4 Auxiliary Switches 14 Section 11 FINAL INST

16、ALLATION INSPECTION 15 Section 12 POWER OPERATED CIRCUIT BREAKERS . 16 Section 13 MAINTENANCE. 17 Section 14 SPARE PARTS 19 Annex A REFERENCES 20 SG 11-2013 Page ii 2013 National Electrical Manufacturers Association Foreword This guide was written to provide basic principles and guidance on maintain

17、ing alternating current outdoor high-voltage circuit breakers. Proposed or recommended revisions should be submitted to: Vice President, Technical Services National Electrical Manufacturers Association 1300 North 17th Street, Suite 1752 Rosslyn, Virginia 22209 This guide was developed by the Switchg

18、ear Section of the Power Equipment Division. Section approval of the guide does not necessarily imply that all section members voted for its approval or participated in its development. At the time it was approved, the Section was composed of the following members: (To be updated by NEMA prior to pu

19、blication) ABB Inc. AREVA T 68F 20C International Standard) be at the proper oil level as indicated by the gauge or marking on the tank. See paragraph 3.2.1 of ANSI/IEEE Std 3-1982 A14. SG 11-2013 Page 10 2013 National Electrical Manufacturers Association 8.4 Filling and Handling De-energized SF6 Ci

20、rcuit Breakers Before the breaker is operated or placed into service, it must be filled with sulfur hexafluoride gas according to the manufacturers instructions. Before performing any work on a circuit breaker that uses SF6 gas, the user must know and understand the procedures involved with handling

21、 of the gas, must have the proper equipment for handling and processing of the gas, and must be trained in the proper use of the equipment. A comprehensive report on the proper handling and use of SF6 gas has been prepared by a working group within IEC. This report is designated as IEC 62271-303 Ed

22、1.0 A11. Additional information is available in references A8, A9, A10, and A15: SF6 gas shall not be vented into the atmosphere (see 8.4.1). SF6 circuit breakers are generally shipped with a positive pressure of approximately 5 psig (35 kPa) of SF6; therefore, evacuation is not required before fill

23、ing. Before filling with SF6, check the pressure gauge to confirm that the pressure has not been lost because of damage or leakage. If pressure is reduced to 0 psig, the user must assume that there is a leak. It will be necessary to find and repair the cause of the leakage, and then pull a vacuum to

24、 approximately 0.5 mm of mercury and hold for 4 hours before filling with SF6. Maintaining the vacuum for a period of time is required where there has been exposure of the interior pole unit assemblies to the atmosphere, in which case the procedures in the maintenance section 13 and section 8.4.2 sh

25、all be followed. 8.4.1 Management of SF6 Gas in High-Voltage Circuit Breakers SF6 is a powerful greenhouse gas, so it should never be deliberately released to the atmosphere. Maintain control of SF6 by an inventory program that tracks the amounts of: a) SF6 purchased b) SF6 received inside of and wi

26、th electrical equipment c) SF6 in service in electrical equipment d) SF6 in storage e) SF6 in gas handling equipment f) SF6 returned to SF6 supplier or equipment manufacturer g) SF6 recycled 8.4.2 Handling of SF6 Gas in High-Voltage Circuit Breakers Use gas checking and handling equipment to approac

27、h target levels noted below. Check with equipment manufacturer to ensure that the equipment can accommodate the process: a) Evacuate air from equipment, hoses, and fittings that are to be filled with SF6. Target pressure level for vacuum: 0.7 mbar (66.7 Pa or 0.5 mm Hg) or lower. This keeps air cont

28、amination of SF6 to acceptable levels of less than 0.02% per filling to a typical pressure of 5 bar (500 kPa or 60 psig). This is important because air cannot be removed by ordinary filters. Separation is difficult and does not recover all the SF6. b) Remove SF6 from the equipment being tested, prod

29、uced, or maintained. Target pressure level for vacuum: 0.7 mbar (66.7 Pa or 0.5 mm Hg) or lower. This will keep handling losses for electrical equipment (typically filled at 5 bar or more (500 kPa or 60 psig) to below 0.02% per handling cycle. It will also, through subsequent dilution of any toxic S

30、F6 decomposition products in the equipment with the backfilled air, ensure that personnel are not exposed above tolerable limits. SG 11-2013 Page 11 2013 National Electrical Manufacturers Association c) Filter SF6 being handled to remove moisture, decomposition products, and other possible filterabl

31、e contaminants, using a molecular sieve, activated alumina, and 1 micron or smaller particle filters. This will keep the SF6 in good condition and also help ensure that personnel are never exposed to toxic decomposition products in SF6. d) Check quality of SF6 intended for re-use in electrical equip

32、ment using: percentage of SF6 instrument (2% maximum air limit) hygrometer or dew point instrument for moisture (120 ppmv maximum limit) chemical reagent tube for decomposition products (50 ppmv total and 12 ppmv SO2 maximum limits) e) Leak check all equipment containing SF6 with special attention t

33、o gas fittings, moving seals, gas handling equipment, and storage facilities. Eliminate leaks to keep overall SF6 emissions below a target leakage rate of 0.5% per year (equipment constructed to older standards may have a higher leakage rate). For more information, refer to references A8, A9, A10, a

34、nd A15. SG 11-2013 Page 12 2013 National Electrical Manufacturers Association Section 9 CONNECTIONS Before making any electrical connections, all leads to be connected to the circuit breaker shall be deenergized with proper safety grounds applied. All terminals shall be fastened to the leads and tig

35、htly clamped to the connection studs. To prevent weakening of the insulation, sharp turns, corners, and edges shall be avoided for insulated wiring. Care shall be observed in installing cables so that bends are not used with a radius smaller than that recommended by the cable manufacturer. 9.1 High

36、Voltage Connections Connections to the circuit breaker are made by terminals or connection bars fastened to the end of the bushing. When tightening the terminal or clamp bolts, care shall be taken not to turn the stud in the bushing (insulator). All nuts on the current-carrying stud shall be set up

37、firmly against the terminal lugs to obtain good contact. The nut shall turn freely on the stud. If the nut does not turn freely, it shall not be forced down with a wrench but shall be tapped lightly on its outer surfaces with a hammer and, at the same time, turned by hand. A nut that cannot be worke

38、d down in this manner will ruin the thread if any attempt is made to force it. If the joints are not made correctly, excessive heating of the circuit breaker may result. Cables and bars shall be properly supported so that the circuit breaker is not subjected to excessive strains. The studs shall not

39、 be subjected to cable or bus-bar strains. Any strains that at first have no apparent effect on the stud alignment will, in time, misalign the studs and adversely affect the closing of the circuit breaker, and poor contact may result. To avoid undue heating, the connecting leads shall have a current

40、-carrying capacity at least equal to that of the current-carrying parts of the circuit breaker. All connection joints shall be clean, bright, free from dents or burns, and preferably silver-plated or the equivalent. Cables, bars, or other conductors shall be properly designed, supported, and braced

41、so as not to exert strains on the bushing or other circuit breaker parts. The use of bends, loops, or flexible connections is recommended. 9.2 Secondary and Control Wiring Connections All external wires shall be run in conduit. Wires shall be separate and remote from high-voltage leads and shall not

42、 be in the same duct or even parallel to the high-voltage leads unless the distance separating the two sets of wiring is sufficient to provide isolation between them as a result of short circuits. The wiring shall be so installed that trouble on one circuit breaker cannot be communicated to the wiri

43、ng of another circuit breaker. Wiring of adequate size shall be used for electrically operated circuit breakers so that, with the full operating current flowing to the operating mechanism, the voltage across the terminals of the operating mechanism will be within rated nominal but not less than the

44、minimum voltage of the range given in ANSI/IEEE C37.06 A3. 9.3 Ground Connections The frame of each unit of a circuit breaker shall be permanently grounded. The usual practice is to connect a heavy cable or solid copper bar to the frame ground pads and to the ground at two diametrically opposite SG

45、11-2013 Page 13 2013 National Electrical Manufacturers Association sides of the circuit breaker. The ground connections shall be adequate to carry maximum line-to-ground fault current for the duration of the fault. Ground connections shall be in accordance with ANSI/IEEE C37.04 A2. For additional de

46、tail on ground connections, refer to IEEE 80 A12. A good permanent low-resistance ground is very important for adequate protection. WARNING AN INADEQUATE GROUND CAN GIVE A FALSE SENSE OF SECURITY TO THOSE WORKING AROUND EQUIPMENT AND MAY ALSO RESULT IN LOSS OF LIFE OR DAMAGE TO THE APPARATUS. SG 11-

47、2013 Page 14 2013 National Electrical Manufacturers Association Section 10 AUXILIARIES 10.1 Tank Lifters Tank lifters for raising or lowering the oil tank are generally used when the weight of the tank is too great to allow handling by hand. One tank lifter in a station is usually sufficient for all

48、 oil circuit breakers of the same type and capacity. It may be operated to lower or raise a tank of one circuit breaker (or unit) and then be moved to another circuit breaker (or unit). When it is necessary to remove the oil tank, care shall be taken that the bushings or contacts are not forced or j

49、arred out of alignment. The tank shall contain sufficient oil before it is replaced, except in the case of tanks that have oil filling connections. It is necessary to have the oil at the correct level to keep the contacts covered properly and also to have the proper air chamber above the oil for best operation of the circuit breaker. 10.2 Other Lifters In the case of oilless circuit breakers, care shall be used in removing heavy parts necessary for maintenance and inspection to prevent damage to the contacts or other parts. Where the parts are so heavy