1、BRITISH STANDARD BS 7632:1993 IEC 594:1977 (Incorporating Amendment 1:1980 and Amendment2: 1987) Internal fuses and internal overpressure disconnectors for capacitors for inductive heat generating plants UDC 621.319.4.022 621.316.545:531.787 + 621.316.923(-191).001.11.001.2.001.4BS7632:1993 This Bri
2、tish Standard, having been prepared under the directionof the Power Electrical Engineering Standards Policy Committee, was published underthe authority of the Standards Board and comes intoeffect on 15March1993 BSI 11-1999 The following BSI references relate to the work on this standard: Committee r
3、eference PEL/46 Special announcement in BSINews, December 1992 ISBN 0 580 21948 8 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Power Electrical Engineering Standards Policy Committee (PEL/-) to Technical Committee PEL/46, upon which t
4、he following bodies were represented: Association of Consulting Engineers British (AC) Capacitor Manufacturers Association (BEAMA Ltd.) ERA Technology Ltd. Electricity Association Rotating Electrical Machines Association (BEAMA Ltd.) Amendments issued since publication Amd. No. Date CommentsBS7632:1
5、993 BSI 11-1999 i Contents Page Committees responsible Inside front cover National foreword ii Section 1. General 1 Scope 1 2 Object 1 3 Definitions 1 Section 2. Performance requirements 4 General 1 5 Disconnecting requirements 1 6 Withstand requirements 2 Section 3. Tests 7 Routine tests 2 8 Type t
6、ests 2 9 Discharge test 2 10 Disconnecting test on fuses 3 11 Disconnecting test on disconnector 3 Appendix A Guide for co-ordination of fuse and disconnector protection 4 Appendix B Test procedures for the disconnecting test on internal fuses 6 Figure 1 Lay-out of a three-phase delta-connected capa
7、citor unit, withtwooverpressure disconnectors (D 1and D 2 ) 4 Figure 2 Principle of design for an overpressure disconnector for self-healing, medium-voltage power capacitors 5 List of references Inside back coverBS7632:1993 ii BSI 11-1999 National foreword This British Standard has been prepared und
8、er the direction of the Power Electrical Engineering Standards Policy Committee. It is identical with IEC594:1977 Internal fuses and internal overpressure disconnectors for capacitors for inductive heat generating plants, incorporating AmendmentNo.1:1980 and AmendmentNo.2:1987, published by the Inte
9、rnational Electrotechnical Commission (IEC). Cross-references The Technical Committee has reviewed the provisions of IEC 110, to which normative reference is made in the text, and has decided that they are acceptable for use in conjunction with this standard. A British Standard does not purport to i
10、nclude all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pa
11、gesi andii, pages1 to6, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS7632:1993 BSI 11-1999 1 Section 1. General 1 Scope 1.1 This standard
12、applies to internal fuses used to protect capacitors for inductive heat generating plants operating at frequencies between40Hz and60Hz, in accordance with IECPublication110, Recommendation for Capacitors for Inductive Heat Generating Plants Operating at Frequencies between40 and24000Hz. 1.2 This sta
13、ndard also applies to internal overpressure disconnectors used to protect self-healing metallized dielectric capacitors. 1.3 This standard does not apply to fuses and disconnectors for which the service conditions, in general, are incompatible with the requirements of the standard, unless otherwise
14、agreed between manufacturer and purchaser. 1.4 Fuses and disconnectors conforming to this standard are designed to isolate faulted capacitor elements or capacitor unit, to allow operation of the remaining parts of that capacitor unit and the bank in which the capacitor unit is connected. Such fuses
15、and disconnectors are not a substitute for a switching device such as a circuit-breaker, or the external protection of the capacitor bank, or part thereof. 2 Object The object of this standard is: to formulate uniform requirements regarding performance and testing; to provide a guide for co-ordinati
16、on of fuse and disconnector protection. 3 Definitions 3.1 Definitions of capacitor parts and accessories are in accordance with IECPublication110. NOTEThe word “element” in this standard is used in accordance with the definitions contained in IEC capacitor publications, and not in accordance with th
17、e IEC fuse publications. 3.2 internal fuse a fuse connected inside a capacitor unit in series with an element or group of elements 3.3 internal overpressure disconnector a disconnecting device inside a capacitor, designed to interrupt the current path in cases of excessive rising pressure NOTE 1This
18、 overpressure disconnector is not a current-limiting fuse. NOTE 2This type of disconnector can also be placed outside the capacitor unit, but is still considered an integral part of the capacitor unit, and shall fulfil the same requirements and pass the same tests as the internal overpressure discon
19、nector. NOTE 3This device is normally used in capacitors of the self-healing type. 3.4 bank protection a general term for all protective equipment for a capacitor bank, or part thereof 3.5 unbalance protection a device sensitive to capacitance difference between branches of the bank normally in bala
20、nce with each other. The capacitance difference may be due to a blown fuse(s), or operation of a disconnector or insulation failure within the bank NOTEOther protective devices, such as overcurrent and earth fault protection, are self-explanatory, since they are commonly used for other applications.
21、 Section 2. Performance requirements 4 General 4.1 The fuse is connected in series to the element(s) which the fuse is intended to isolate if the element(s) becomes faulty. The range of currents and voltages for the fuse is therefore dependent on the capacitor design, and in some cases also on the b
22、ank in which the fuse is connected. The operation of an internal fuse is in general determined by one or both of the two following factors: the discharge energy from elements or units connected in parallel with the faulty element or unit; the power-frequency fault current. 4.2 The disconnector is in
23、tended to interrupt the current to all elements of the capacitor. The proper operation of the disconnector is dependent on the leak-tightness of the container during the life of the capacitor. 5 Disconnecting requirements 5.1 The fuse shall enable the faulty element to be disconnected when electrica
24、l breakdown of elements occurs in a voltage range, in which u 1is the lowest, and u 2the highest (instantaneous) value of the voltage between the terminals of the unit at the instant of fault. The recommended values for u 1and u 2are the following:BS7632:1993 2 BSI 11-1999 NOTE 1The u 1and u 2values
25、 above are based on the voltage that may normally occur across the capacitor unit terminals at the instant of electrical breakdown of the element. The u 2values are of a transient nature. The purchaser shall specify if the u 1and u 2values differ from the stated ones. If so the values stated in Sub-
26、clauses10.1 and 10.4 shall be changed accordingly. NOTE 2The requirements are valid for capacitors switched by a restrike-free circuit-breaker. If the breakers are not restrike-free, other requirements shall be agreed between manufacturer and purchaser. 5.2 The disconnector shall enable the faulty c
27、apacitor unit to be disconnected for voltages up to and including u 3 . The recommended r.m.s. value is u 3 =1.2U N . NOTEThe purchaser shall specify if this voltage will be exceeded. 6 Withstand requirements 6.1 After operation, the fuse assembly and the disconnector must withstand full element vol
28、tage and full voltage between the terminals of the disconnected capacitor respectively, plus any unbalance voltage due to fuse or disconnector action, and any short-time transient overvoltages normally experienced during the life of the capacitor. 6.2 Throughout the life of the capacitor, the discon
29、nector shall be capable of carrying continuously a current equal to or greater than1.1times the maximum permissible unit current and the fuses capable of carrying continuously a current equal to or greater than the maximum permissible unit current divided by the number of parallel fused paths. NOTET
30、he requirements are valid if the capacitors are switched by a restrike-free circuit-breaker. If the breakers are not restrike-free, other requirements are to be agreed between manufacturer and purchaser. 6.3 The fuse and the disconnector shall be capable of withstanding the inrush-currents due to th
31、e switching operations expected during the life of the capacitor. 6.4 The fuse connected to the undamaged element(s) must be able to carry the discharge currents due to the breakdown of element(s). 6.5 The fuses and disconnectors must be able to carry the currents due to short-circuit faults externa
32、l to the unit(s) on the bank occurring within the voltage range in accordance with Sub-clause5.1. Section 3. Tests 7 Routine tests No routine tests are required. 8 Type tests 8.1 The type tests comprise: Discharge test (Clause 9). Disconnecting test on fuses (Clause 10). Disconnecting test on discon
33、nector (Clause11). In addition, the fuses and disconnectors shall be able to withstand all type tests of the capacitor units in accordance with IEC Publication110. 8.2 Type tests of fuses are performed either on one complete capacitor unit or, at the choice of the manufacturer, on two units, one uni
34、t being tested at the lower voltage limit, in accordance with Sub-clause 10.1 and one unit at the upper voltage limit. The unit(s) shall have passed all routine tests stated in IECPublication110. NOTEDue to testing, measuring and safety circumstances, it may be necessary to make modifications to the
35、 unit(s) under test; for example, those indicated in Appendix B. See also the different test methods given inAppendix B. 8.3 Type tests of disconnectors are performed on a capacitor unit that shall have passed all routine tests stated in IECPublication110. 8.4 Type tests are considered valid if they
36、 are performed on capacitors of a design identical with that of the capacitor offered, or on a capacitor of a design that does not differ from it in any way that might affect the properties to be checked by the type tests. 9 Discharge test 9.1 The fuses and disconnectors shall be subjected to five d
37、ischarges within10min from a d.c. voltage equal to2.5U Nthrough a gap situated as close as possible to the capacitor, without any additional impedance in the circuit. 9.2 To prove that the fuses or disconnector have not operated, a capacitance measurement shall be made before and after the test. A m
38、easuring method shall be used that is sufficiently sensitive to detect the capacitance change caused by one blown fuse.BS7632:1993 BSI 11-1999 3 10 Disconnecting test on fuses 10.1 Test procedure The disconnecting test on fuses is performed first at the lower a.c. test voltage of 0.8U Nand then, as
39、soon as possible after the blowing of one fuse, at the upper a.c. test voltage of 2.2U N , until the blowing of another fuse. Certain test methods are indicated in Appendix B. NOTEIf the test is carried out with d.c., the test voltage shall be times the corresponding a.c. test voltage. 10.2 Capacita
40、nce measurement After the test, capacitance shall be measured to prove that the fuse(s) has (have) blown. A measuring method shall be used that is sufficiently sensitive to detect the capacitance change caused by one blown fuse. 10.3 Inspection of the unit Before opening, no significant deformation
41、of the container shall be apparent. After opening the container, a check should be made to ensure that: a) no significant deformation of sound fuses is apparent; b) not more than one additional fuse (or one-tenth of fused elements directly in parallel) has been damaged (Appendix B, Note 1). If metho
42、d b) in Appendix B is used, the note must be observed. NOTE1A small amount of blackening of the impregnant will not affect the quality of the capacitor. NOTE 2Dangerous trapped charges may be present on elements disconnected either by operated fuses or by damage to their connections. All elements sh
43、ould be discharged with great care. 10.4 Voltage test after opening the container A voltage test shall be carried out by applying for10s a d.c. test voltage equal to3.5times the rated voltage of the elements across the broken down element and the gap in its blown fuse. During the test, the gap shall
44、 be in the impregnant. No breakdown over the fuse gap is allowed. NOTEFor units with all elements in parallel and for all units if test procedure b) or c) or d) or e) indicated in Appendix B is used, this test can be replaced by an a.c. test before the opening of the unit. The test voltage between t
45、he terminals is calculated using the capacitance ratio such that the voltage across the breakdown element and the gap in its blown fuse is the value given in Sub-clause 10.4 divided by. 11 Disconnecting test on disconnector 11.1 Test procedure The capacitor is preheated in a chamber before applying
46、the test voltage until all parts reach a temperature of60 C. An a.c. test voltage of1.6U Nshall be applied until the disconnector interrupts the current through the capacitor. If the disconnector does not operate within8h, the test voltage is raised to1.75U N . If, after a further8h, the disconnecto
47、r still has not operated, the test voltage should finally be raised to2U N , until the current is interrupted. If no interruption is achieved, the temperature may be further raised at the option of the manufacturer. NOTEPrecautions shall be taken when performing this test against the possible explos
48、ion of a capacitor unit. 11.2 Capacitance measurement After the test, capacitance shall be measured to prove that the disconnector has operated. 11.3 Inspection of the unit Only slight traces of impregnant on the outside of the capacitor are allowed. 11.4 Voltage tests A voltage test between termina
49、ls shall be carried out by applying, for10s, an a.c. voltage equal to2.15U N , or a d.c. voltage equal to4.3U N . In addition, a voltage test between terminals and container shall be made by applying, for10s, the test voltage given by IECPublication110. The test voltage shall be applied after the capacitor has cooled to room temperature. No internal breakdown is allowed. NOTEThe current shall be recorded during the test. 2 2BS7632:1993 4 BSI 11-1999 Appendix A Guide for co-ordination of fuse and disconnector protection General The fuse is connected in serie
