1、BRITISH STANDARD BS787-3:1971 Specification for Mining type flameproof gate-end boxes Part 3: Gate-end boxes with lighting transformersBS787-3:1971 This BritishStandard, having been approved by the Mining andQuarrying Requisites Industry Standards Committee,was published undertheauthority oftheExecu
2、tive Boardon 26March1971 BSI01-2000 The following BSI references relate to the work on this standard: Committee referenceMQE/16 Draft for comment70/4838 ISBN 0 580 06079 9 Co-operating organizations The Mining and Quarrying Requisites Industry Standards Committee, underwhose supervision this British
3、Standard was prepared, consists of representatives from the following Government department and scientific and industrial organizations: Association of Mining Electrical and Mechanical Engineers* British Electrical and Allied Manufacturers Association* British Steel Industry Department of Trade and
4、Industry* Engineering Equipment Users Association Federation of Associations of Mining Equipment Manufacturers Federation of Manufacturers of Construction Equipment and Cranes Institute of Quarrying Institution of Mechanical Engineers Institution of Mining Engineers Mechanical Handling Engineers Ass
5、ociation National Coal Board* The Government department and industrial organizations marked with anasterisk in the above list, together with the following, were directly represented on the committee entrusted with the preparation of this BritishStandard: Council of Underground Machinery Manufacturer
6、s Amendments issued since publication Amd. No. Date CommentsBS787-3:1971 BSI 01-2000 i Contents Page Co-operating organizations Inside front cover Foreword ii 1 Scope 1 2 Definitions 1 3 Service conditions 2 4 Ratings 2 5 Marking 2 6 Design and construction 3 7 Tests 5 8 Information to be supplied t
7、o the manufacturer with the enquiry 6 Appendix A Metric values 7 Figure 1 Arrangement of busbar chamber end flange, terminalsandinterconnections 8 Figure 2 Busbar interconnecting trunk 9 Figure 3 Skid coupling arrangement 10 Figure 4 Busbar end cover 11BS787-3:1971 ii BSI 01-2000 Foreword This stand
8、ard makes reference to the following BritishStandards: BS88, Cartridge fuses of voltage ratings up to660volts. BS159, Busbars and busbar connections. BS171, Power transformers. BS229, Flameproof enclosure of electrical apparatus. BS542, Cable glands and sealing boxes for association with apparatus f
9、or use at mines. BS775, Contactors. BS861, Air-break switches and isolators. BS1259, Intrinsically safe electrical apparatus and circuits for use in explosive atmospheres. BS3454, 3.3kV300A interchangeable bolted flameproof cable couplers and adaptors (including660V300A adaptors) primarily for use i
10、n mines. BS3871, Miniature and moulded case circuit-breakers. This BritishStandard has been prepared, under the authority of the Mining and Quarrying Requisites Industry Standards Committee, to standardize the main features of gate-end boxes used primarily in coal mining in the United Kingdom. It is
11、 recognized that the term “gate-end box” is quite general and may be applied to boxes containing different essential components, such as contactors, circuit-breakers, lighting transformers,etc., depending upon the purpose for which they are to be used. BS787 was issued in1938, and has been revised a
12、nd re-issued as BS787-1 andBS787-2 to cover gate-end boxes in which the essential apparatus is, respectively, an air-break electrically operated contactor and an air-break circuit-breaker. This additional specification, designated as BS787-3, extends the scope of the original BS787 by covering gate-
13、end boxes in which the essential apparatus is a lighting transformer. It is envisaged that an additional part of this BritishStandard will be issued to cover gate-end boxes for drill units. NOTEWhere metric equivalents have been given (seeAppendix A), the figures in imperial units are to be regarded
14、 as the standard. The metric conversions are approximate. More accurate conversions should be based on the relevant tables in BS350, “Conversion factors and tables”. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible
15、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, pagesi andii, pages1 to12, an inside back cover and a back cover. This standard has been updated
16、 (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS787-3:1971 BSI 01-2000 1 1 Scope This BritishStandard covers flameproof gate-end boxes designed primarily for use, in the mining industry, on a3-phase a.c. system
17、 having a line voltage of up to650V, to provide electrical supply for single-phase lighting circuits. 2 Definitions For the purposes of this BritishStandard, the following definitions apply: 2.1 gate-end box a flameproof enclosure containing electrical apparatus such as switchgear and/or protective
18、gear designed primarily for use underground NOTEFor the purposes of this standard the apparatus is essentially an air-cooled transformer with associated equipment to provide electrical supply for lighting circuits. 2.2 isolating switch a switch which isolates a circuit and is capable of making and b
19、reaking not less than its rated current at rated voltage 2.3 transformer a piece of apparatus without moving parts which, by electro-magnetic induction, transforms alternating voltage in one winding into alternating voltage in one or more other windings, usually at different values 2.4 cable couplin
20、g unit (flit plug) a unit consisting of a cable sealing box and cable gland together with means for connecting the cable conductors to insulated contact tubes within the sealing box. The unit is designed to receive the cable; to provide room to spread and connect the cores; to protect the cores; to
21、allow for the attachment of the cable gland; to provide for sealing the insulating materials of the cable, and to facilitate ready connection to or disconnection from a similar unit or other apparatus 2.5 cable coupler adaptor a device used to connect a cable coupling unit to apparatus. It may eithe
22、r be separate from or integral with the flameproof enclosure of the apparatus to which the cable coupling unit is to be connected for the purposes of this standard, the term “adaptor” also includes the unit to connect other types of cable terminations to apparatus 2.6 cable sealing and dividing box
23、a box designed to receive and protect the end of the cable, with provision for sealing the conductors and the insulating material of the cable with a suitable compound, and having a cable gland for attaching the cable to the box, together with any terminals provided for connection to the conductors
24、of the cable within the box. The box may form part of, or be detachable from, the apparatus with which it is associated 2.7 detachable cable sealing box a cable sealing box so designed that it can be detached from associated apparatus without cutting the cable and without disturbing the sealing 2.8
25、flameproof enclosure a flameproof enclosure for electrical apparatus is one that will withstand, without injury, any explosion of the prescribed flammable gas that may occur within it under practical conditions of operation within the rating of the apparatus (and recognized overloads, if any, associ
26、ated there-with) and will prevent the transmission of flame such as will ignite the prescribed flammable gas which may be present in the surrounding atmosphere 2.9 bolted plug and socket a plug and socket, the two portions of which, when fully engaged, are designed to be held together by one or more
27、 bolts or screws, or studs and nuts, in such a way that they cannot be disengaged without the use of tools 2.10 rating the value assigned by the manufacturer to some limits of performance under certain specified conditions known as the “rated conditions” 2.11 intrinsically safe circuit a circuit in
28、which any electrical sparking that may occur in normal working, under the conditions specified by the certifying authority, and with the prescribed components, is incapable of causing an ignition of the prescribed flammable gas or vapourBS787-3:1971 2 BSI 01-2000 3 Service conditions Gate-end boxes
29、in accordance with this specification are suitable, within the limits of their ratings, for installations where the service conditions are not more severe than the following. 3.1 Ambient temperature. A peak value not exceeding40 C with an average value not exceeding35 C over24-hour periods. 3.2 Alti
30、tude. An altitude not exceeding3300ft(1000m) above sea-level. NOTEWhen a gate-end box intended for service at high altitude is tested near sea-level, the limits of temperature rise, asindicated in6.12, should be reduced by1% for each1000feet(300m) above sea-level at which the gate-end box is intende
31、d to work in service. The correction does not apply for altitudes below3300feet(1000m). 4 Ratings 4.1 Supply voltage. The maximum supply line voltage shall be650V. Standard gate-end boxes shall be suitable for a voltage variation at least10% below and at least6% above the declared voltage of the sup
32、ply for which they are designed, subject again to the maximum of650V. 4.2 Supply frequency. The standard frequency shall be50Hz. Gate-end boxes designed for other that the standard frequency, within the range of4260Hz, provided they satisfy all other requirements specified herein, shall be deemed to
33、 comply with this standard. 4.3 Output voltage. The following are the preferred output voltages: Other voltages may be agreed between supplier and purchaser. 4.4 Output. The following are the preferred outputkVA ratings: Other ratings may be agreed between supplier and purchaser. 4.5 Current rating
34、of busbars. The standard current rating of busbars, where fitted, shall be300A. Busbars of other ratings agreed between manufacturer and purchaser shall also be deemed to comply with this specification. 5 Marking 5.1 Nameplates. All gate-end boxes shall be permanently marked with the following parti
35、culars: 1) The registered trade name or trademark of the manufacturer or his agent. 2) Manufacturers type or reference. 3) Manufacturers serial number. 4) Maximum rated output inkVA. 5) Supply voltage or voltage range. 6) Output voltage or voltage range. 7) Frequency. 8) The number of the flameproof
36、 certificate and the number or numbers indicating the group of gases and vapours covered by the certificate. 9) A reproduction of the registered flameproof mark (if the manufacturer holds a licence to apply this mark), or any other mark required by the Department of Trade and Industry. 10) Where app
37、licable the intrinsic safety certificate details as required by the Department of Trade and Industry. 11) Additional marking as may be required by any other certifying authority. 5.2 Terminal marking. Terminal markings, if required, for incoming and outgoing connections shall be agreed between manuf
38、acturer and purchaser. 5.3 Busbar interconnecting trunks. All busbar interconnecting trunks (see6.3) shall be permanently marked with the following particulars: 1) Manufacturers registered trade name or trademark. 2) Manufacturers type or reference. 5.4 Busbar end covers. All busbar end covers (see6
39、.4) shall be marked with the following particulars: 1) Manufacturers registered trade name or trademark. 2) Manufacturers type or reference. 5.5 Diagrams. Diagrams of connections, which shall be durable and legible, shall be securely attached in an accessible position within the main chamber. 115V a
40、nd125V or 115V and230V or 125V and250V. 1.0kVA or 2.5kVA or 4.5kVA.BS787-3:1971 BSI 01-2000 3 6 Design and construction A gate-end box in accordance with this specification shall comply with the requirements of BS229 1)and shall have been certified, by the Department of Trade and Industry, as flamep
41、roof for GroupI gases (methane/firedamp). The gate-end box may also be certified for any group of gases by any appropriate certifying authority, as may be required. NOTEWhen applying for flameproof certification, it will be necessary, for compliance with BS229, “Flameproof enclosure of electrical ap
42、paratus”, for the manufacturer to specify the types of fittings for which he has made provision in accordance with6.2 to6.6 inclusive. Unless otherwise agreed between manufacturer and purchaser no external component shall be made of aluminium, magnesium or titanium, neither shall any alloy containin
43、g aluminium and/or magnesium and/or titanium be used unless the total content of these three constituents does not exceed15% by weight, and in which the content of magnesium and titanium together does not exceed10% by weight. No external part shall be painted or coated with preparations containing,
44、in metallic form, aluminium, magnesium or titanium. NOTEThese limitations have been imposed to avoid the hazards of incendive sparking due to friction between rusted steel or iron and the metals described. The following subclauses relate to the basic unit: The following subclauses relate to optional
45、 items: The following subclauses relate to both the basic and optional items: 6.1 Enclosing case. The enclosing case shall comprise a main chamber and isolator/busbar chamber, each with suitable access cover, and shall incorporate, or be adapted for mounting on, skids to facilitate transport. The de
46、sign shall include such provision as will permit, without structural alteration, the attachment of adaptors, cable fittings, interconnecting trunks,etc., as specified in6.2 to6.5, in any combination that may be required for normal installation and operation of the gate-end box. To facilitate this, a
47、 preferred design of busbar-coupling flange is shown in Figure 1 but other designs shall be deemed to comply with this standard provided they satisfy all other requirements specified herein. 6.2 Incoming and throughgoing cable. For the attachment of incoming or throughgoing cables the busbar chamber
48、 shall be fitted at either end, or both ends, as required, with: 1) an adaptor suitable for the reception of a cable coupling unit (flit plug), e.g.as specified in BS3454 2) , 2) a detachable cable sealing and dividing box, e.g.as specified in BS542 3) , or 3) any other fitting which is approved by
49、the certifying authority. 6.3 Coupling of units. When two or more gate-end boxes are required to be coupled together, this shall be achieved either by: 1) the bolting together of appropriate flanges, or 2) the fitting of interconnecting busbar trunking. Where the preferred design of busbar flange indicated in6.1 is adopted the interconnecting busbar trunk shall conform to the dimensions and tolerances shown in Figure 2. The preferred minimum width of flange shall be1in. The coupling arrangements shall be such as to prevent, in normal use, undue strain being pla
