GB2175449A - Flameproof/modular switchgear - Google Patents

Abstract

A flameproof switchgear is formed by a plurality of modular units 1, D1 assembled together to form a complete switchgear structure, one of the units 1 containing a circuit breaker, and another at least one manually operable disconnector 16, with connections between components of adjacent units. By this means a manufacturer can assemble various units to suit different applications. Electrical connections between units are made via moulded insulators bolted to machined faces of respective units. <IMAGE>

Description

SPECIFICATION Switchgear This invention relates to switchgear designed for use in atmospheres containing or susceptible to contamination by a combustible gas, such as methane. Such switchgear is required to be accommodated in enclosures which conform to certain flameproof standards. In particular it is necessary to divide the whole of a flameproof switchgear structure into separate compartments, each of which is sealed from adjacent compartments, and each containing a particular part of the overall equipment. By this means the various parts of the equipment are segregated from each other such that if a flame is initiated in one compartment the probability of such a flame travelling to another compartment and igniting the gas or damaging the parts of the equipment contained therein is very much reduced.

According to the present invention a flameproof switchgear structure comprises a plurality of modular units each in the form of a separate enclosure accommodating a respective part of the switchgear, the units being capable of being assembled together to form a complete flameproof structure in which one of the units contains a circuit breaker, and another of the units contains at least one manually operable disconnector, with connections formed between electrical components of adjacent units.

By this means different disconnector units may be selectively fitted to a common form of circuit breaker unit, thereby enabling the manufacturer or user to construct or modify completed switchgear equipment for a variety of applications. Moreover additional enclosures containing other elements, such as cable connection terminals, may be fitted to a particular circuit breaker/disconnector assembly depending upon the function the switchgear structure is required to perform.

The circuit breaker unit will normally be provided with an access opening, cioseable by a cover, to provide access to a circuit breaker module accommodated within it, or to enable the module to be removed for replacement or servicing. In such a case the circuit breaker unit preferebly carries either as an integral part or as a further unit attached thereto an interlock mechanism which interconnects with the disconnector switch of a disconnector unit fitted to the circuit breaker unit and is operable to prevent opening of the access cover if the disconnector is in the "On" or "Earth" position, as described in co-pending U.K. Patent Application No. 8510203.

It will be understood that mating faces of assembled modular units should be appropriately machined so as to form flameproof joints between the units.

The invention will be further explained by describing, by way of example, with reference to Figs. 1 to 6 of the accompanying drawings, a number of different flameproof switchgear structures formed of two or more separate modular units in accordance with the invention.

Figs. 1A and 1B show different views, in diagrammatic form, of an essential unit S of the structure, comprising a flameproof enclosure 1 containing a three-phase vacuum circuit breaker module M designed to be operated by a suitable actuating mechanism, which may be as described in co-pending U.K. Patent Application No. 8510205.

The enclosure 1 is provided, at the front, with an access opening 2 closeable by a cover 3, the circuit breaker module M is mounted on a chassis so that it is readily removable from the enclosure. This enables another module to be substituted for the original, thus allowing the switchgear to be returned to service while the original module is receiving inspection or maintenance.

The circuit breaker module M is arranged to make electrical contact, via spring loaded butt contacts C, with disconnector switches or cabling facilities, and may be lowered by a lever system (not shown) from the service position to enable it to be withdrawn from the enclosure through the access opening 2. The cover 3 is arranged to be opened by a sliding hinged motion by means of a handle 4, the movement of which is controlled by an interlock mechanism I as described in co-pending U.K. Patent Application No. 8510203.

A solid state control and protection unit is housed in the cover as at 5, windows giving means for visual examination of instruments and settings of overload, short circuit and earth fault currents, with through shafts giving means for test and control functions.

Figs. 2A and 2B illustrate a modular disconnector unit D1 incorporating an enclosure 6 shown secured by bolts to the top of the enclosure 1 of the unit S, so as to constitute with it one form of switchgear structure in accordance with the invention, for connection to a high voltage flameproof transformer. The enclosure 6 of the unit D1 is itself divided into five compartments 8 to 12. The compartments 8 and 9 provide for cable connections to cable adaptors and bus cables 7 routed through a further compartment 10 in the form of ducting via sealing glands 13. The compartment 11 contains terminals 14 for cable connections to the transformer via a rear flange 15.The final compartment 12 of the disconnector unit D1 contains the three-phase manually operated disconnctor switch 16 connectable to an interlock mechanism I when the unit is mounted on the unit S as aforesaid.

An alternative structure is illustrated in Figs.

3A and 3B. In this case a modular disconnector unit D2 is bolted to the top of the enclo sure 1 of the unit S in place of the unit D1 of Fig. 2. This second unit comprises an enclosure 18 divided into three compartments 19, 20, 21 in which the compartment 19 accommodates incoming cable connection terminals 22, the compartment 20 incorporates a manually operable three-phase interlocked disconnector switch 24 as in the case of the previous embodiment, and the compartment 21 contains the outgoing cable connection terminals 25. The assembly of the units S and D2 provides a basic face isolation equipment.

A third embodiment as shown in Figs. 4A and 4B comprises a two-compartment modular disconnector unit D3 bolted to the top of the enclosure 1 of the unit S and a second single compartment modular unit 27 bolted to the top of the unit D3. The first compartment 28 of the unit D3 contains terminals 29 for outgoing cable connections, and the compartment 30 contains a manually operated threephase interlocked disconnector 31 as in the case of the embodiments of Figs. 2 and 3.

The single compartment 32 of the unit 27 contains three-phase bushbars 33 which may be directly connected to adjoining units to form a switchboard. The assembly of units shown in Figs. 4A and 4B comprises a basic outgoing feeder equipment.

The structure illustrated in Figs. 5A and 5B is similar to that of Figs. 4A and 48 in that it comprises two modular units D4, 32, mounted on top of the enclosure 1. Thus the unit D4, which has two compartments 36, 37, is bolted directly to the top of the enclosure 1, and the other single compartment unit 32, which is the same as that of Fig. 4, is bolted to the unit D4. Each of the compartments of the unit D4 contains a manually operated disconnector 38 ganged to operate simultaneously and interlocked as in the previous embodiments, and has a further unit 39 bolted to its right hand face (as in the Fig. 5A view) to provide for incoming cable connections. This assembly of units provides a basic incoming feeder equipment.

The structure of Figs. 6A and 6B again has two modular units D5, 42 mounted on top of the enclosure 1. The unit D5, which is bolted directly to the enclosure 1 has two compartments 43, 44 each containing a manually operated disconnector 45 ganged to operate simultaneously and interlocked as above described. The unit 42 is also divided into two compartments 46, 47 each containing busbars 48, and this arrangement provides a basic bus section equipment.

Bolted access covers A are situated as shown in each of the figures. Further bolt-on compartments 51, 52 or 53 as shown in Fig.

6 may be used as an alternative to the covers on the busbar chambers to give various cabling facilities. In all the embodiments described, electrical connections between compartments are made via moulded insulators bolted to machined faces of the respective enclosures to maintain the flameproof barrier between compartments.

It will be seen that the modular structure of the invention enables a manufacturer or user to utilise one form of circuit breaker unit with selected disconnector units possibly with one or more other units to obtain a particular form of flameproof switchgear structure, depending upon the use to which it is to be put, and a number of differently formed structures in accordance with the invention may be assembled together to form a complete switchboard assembly.

Claims (5)

1. A flameproof switchgear structure comprising a plurality of modular units each in the form of a separate enclosure accommodating a respective part of the switchgear, the units being capable of being assembled together to form a complete flameproof structure in which one of the units contains a circuit breaker, and another of the units contains at least one manually operable disconnector, with connections formed between electrical components of adjacent units.

2. A flameproof switchgear structure according to Claim 1 in which the circuit breaker unit is provided with an access opening, closeable by a cover, to provide access to a circuit breaker module accommodated within it, or to enable the module to be removed for replacement or servicing, and carries either as an integral part, or as a further unit attached thereto, an interlock mechanism which interconnects with the disconnector switch of a disconnector unit fitted to the circuit breaker unit and is operable to prevent opening of the access cover if the disconnector is in the "On" or "Earth" position.

3. A flameproof switchgear structure according to Claim 1 or 2 wherein electrical connections between compartments of adjacent units are made via moulded insulators bolted to machined faces of the respective enclosures.

4. A switchboard assembly incorporating a plurality of switchgear structures according to any preceding Claim.

5. A flameproof switchgear structure comprising a plurality of modular units assembled together substantially as shown in and as hereinbefore described with reference to Figs.

2A and 28 or 3A and 3B or 4A and 4B or 5A and 5B or 6A and 6B of the accompanying drawings.