GB2207821A

GB2207821A - Fuse assemblies

Info

Publication number: GB2207821A
Application number: GB08818625A
Authority: GB
Inventors: Alfred G Pratt
Original assignee: WINSTON ENG CO Ltd
Current assignee: WINSTON ENG CO Ltd
Priority date: 1987-08-07
Filing date: 1988-08-05
Publication date: 1989-02-08
Anticipated expiration: 2008-08-05
Also published as: EP0302753A2; GB2207821B; GB8718804D0; EP0302753A3; GB8818625D0

Description

2 20 Fuse Assemblies for Electrical Systems This invention relates to

electrical systems and, in particular, fuse assemblies therefor.

Where an electrical system is installed within a classified area, eg potentially explosive and/or inflammable atmospheres, there is a requirement for fuse assemblies used in the system to be fully protected to an explosion-proof/flame-proof British Standard (BS 5501 Part 5). Thus, it is necessary for the fuse assemblies to be tested and certified by an appropriate authority as complying with BS 5501.

In order to comply with safety regulations, it is the present practice to install the individual fuse assembl.ies together within an explosionproof/flame-proof enclosure. This practice has the disadvantage that a suitable enclosure is large, heavy and expensive to produce.

An object of the present invention is to provide an alternative fuse assembly for use in hazardous atmospheres which does not suffer from the disadvantage discussed above.

According to the present invention a fuse assembly for use in harzardous atmospheres comprises an elongate enclosure which is explosion-proof/flame-proof and dimensioned to accept a specified size of fuselink, the enclosure having an opening through which the fuselink is fitted closable by a tightly fitting cover, electrical connectors extending through end walls of the 1 enclosure and supported in spaced relationship within the enclosure and fixing means whereby the terminals of the fuselink can be directly and fixedly connected to respective connectors.

Preferably, the cover is hinged at one end to the enclosure and has fixing means at the other end.

Conveniently, the enclosure and cover would be moulded from a suitable plastics material and would be of a thickness sufficient to ensure the integrity of the 10 enclosure should an internal spark or explosion occur.

In order that the invention may be readily understood, one embodiment will now be described, with reference to the accompanying drawing, in which:

Figure 1 is a plan view of the enclosure, with 15 its cover removed.

Figure 2 is b. side view of the enclosure and cover, partly in section.

Figure 3 is a view similar to Figure 1 with the form of an elongate rectangular case 1 dimensioned to 20 accommodate a cartridge fuselink manufactured to BS 88, Part 2. The assembly comprises the elongate case 1 and cover 2, which are moulded from a suitable plastics material, and of a suitable thickness, to ensure flameproof and explosion proof integrity. The case 1 has an elongate opening 3 which is shaped and dimensioned to v It 3 enable the fuselink 6 to be passed through into the case. A pair of connectors 4 are provided, which are manufactured to BS 5501, Part 6, and have threaded holes in their heads 5 located within the case 1 at opposite ends thereof, the threaded holes in the heads being spaced a distance corresponding to the spacing of the apertures (fixing centres) normally provided in the terminals 6a of the cartridge fuse link 6. The connectors 4 include limbs 7 which pass through suitable apertures in the respective end walls of the case. Preferably, the connectors are fitted during moulding of the case. The outer, external ends of the limbs 7 are provided with cable clamping facilities in the form of screwed cable connectors 8.

The cover 2 is dimensioned and shaped to correspond to the wall of the case defining the opening 3 and is hinged at one end via integral bosses 9 and 10 in the cover and case respectively and a pin 11 therethrough. To prevent removal of the pin 11 it is inserted fully within a blind hole, through the parts 9 and 10 and the insert end is then sealed with expoxy resin. The other end of the cover is provided with a captive screw 12 which can be screwed into a threaded aperture provided in a thickening 13 of the respective end wall, and thereby tightened down onto the case. 25 The fuselink 6 is fixedly connected via its terminals 6 directly to the heads 5 of the connectors 4 via fixing screws 14. As shown, the side walls of the enclosure 1 have - 4 spacer lugs 15 f ormed therein so that a number of fuse assemblies can be mounted side-by-side on a fuseboard, or in a further enclosure with a miniumum space defined between them. Conveniently, they may be.fitted squarely together on the fuseboard by providing a DIN rail on which the assemblies are mounted via a shaped slot 16 in the bottom wall of each enclosure. To retain each enclosure in position on the DIN rail, a plastics clip 17 is provided which is slidably mounted in a bore 18 opening 10 into the groove 16.

is i

Claims

1 1. A fuse assembly for use in hazardous atmospheres comprising an enclosure which is explosion proof/ flameproof, characterised in that the enclosure (1) is dimensioned to accept a single specified size of elongate fuselink (6), in that the enclosure has an opening (3) through which the fuse link is fitted which is closable by a tightly fitting cover (2), in'that electrical connectors (4) extend through end walls of the enclosure and are supported in spaced relationship within the enclosure, and in that fixing means (14) are provided whereby the terminals of the fuselink can be directly and fixedly connected to respective connectors.

2. A fuse assembly according to claim 1, characterised in that the cover (2) is hinged (via parts 9 to 11) at one end to the enclosure (1) and has fixing, means (12) at the other end.

A fuse assembly according to claim 1, or 2 characterised in that the enclosure (1) and cover (2) are moulded from a suitable plastics material and are of a thickness sufficient to ensure the integrity of the enclosure should an internal spark or explosion occur.

4. A fuse assembly according to any one of claims 1 to 3, characterised in that each enclosure is formed with a transverse shaped slot (16) whereby a number of said assemblies can be mounted side-by-side on a DIN rail.

6 - 5. A fuse assembly according to claim 4, characterised in that each enclosure is provided with spacers (15) on its side walls to define a minimum clearance between the mounted assemblies.

6. A fuse assembly constructed and arranged for use substantially as hereinbefore described, with reference to and as shown in, the accompanying drawing.

1 Published 1988 at The Patent Office. State House. 6671 High Holborn, London WC1R 4TP. Further copies maybe obtained from The Patent OTfice, Sales Branch. St Mary Cray, Orpington, Kent BR5 3RD. Printed by Multiplex techniques ltd, St Mary Cray. Kent. Con. 1,87.