GB2167613A

GB2167613A - Electrically interconnecting relatively movable conductors

Info

Publication number: GB2167613A
Application number: GB08528240A
Authority: GB
Inventors: John Leyton Davenport; Henry Spillman Wood
Original assignee: Associated Electrical Industries Ltd
Current assignee: Associated Electrical Industries Ltd
Priority date: 1984-11-21
Filing date: 1985-11-15
Publication date: 1986-05-29
Also published as: GB8528240D0; GB2167613B; AU584653B2; IN164970B; MX160664A; GB8429432D0; NZ214146A; AU5021485A

Abstract

A connector for a circuit breaker in which an electric current is required to be passed between two relatively movable conductors comprises conductor bulbous portions (33, 37) which fit into opposite ends of a conducting cylinder (34), the walls of which are slotted (at 35) so as to cause them to apply spring pressure against the bulbous portions, whilst allowing relative movement of the members. <IMAGE>

Description

SPECIFICATION Electrical apparatus This invention relates to electrical apparatus of the kind incorporating two relatively moving, electrically conducting, members between which an electric current is required to be passed, and relates especially, though not exclusively, to circuit breakers and like equipment in which current is required to be transferred between a movable contact and a fixed conductor.

According to the invention, in electrical apparatus of the kind referred to, a first conducting member movable to a limited extent along a linear path carries a transverse projection terminating in a bulbous end, which fits into one end of a conducting cylinder, and a second conducting member carries a second bulbous portion which projects into the opposite end of the cylinder, the walls of the cylinder being slotted and of such diameter that they apply spring pressure against both bulbous portions whilst allowing tilting movement of the cylinder to take place on movement of the first conducting member.

Preferably the wall of the cylinder is formed with longitudinal slots extending partly along it from opposite ends. The slots conveniently extend the greater part of the length of the cylinder alternately from opposite ends.

Preferably one of the bulbous portions is held in position within the cylinder by an annular locating groove formed at an appropriate position in the inner surface of the cylinder. An encircling band is conveniently disposed around the cylinder fo!!owing the insertion of the bulbous portion into the groove from the respective end of the cylinder, so as to prevent withdrawal of the bulbous portion from the cylinder.

One circuit breaker embodying the invention will now be described by way of example, with reference to Figures 1 to 3 of the accompanying schematic drawing, in which Figures 1 and 2 represent an axial section and or transverse section respectively through the circuit breaker, and Figure 3 represents an enlarged section through a part of the circuit breaker.

The circuit breaker comprises a vacuum switch 1 containing fixed and movable contacts 2, 3 respectively mounted within an outer casing 4, which is of generally cylindrical shape, having an opening 5 at one end. A short tubular stub 6 projects from the side of the casing 4, as shown.

The outer end of the stem 2.2 of the fixed contact 2 is connected electrically, by means of a coupling 7, to a conducting rod 8 which projects through the opening 5. The rod 8 is surrounded by a tube 9 of insulating material such as an epoxy or polyurethane resin, the inner end 11 of tube being of enlarged external diameter. Adjacent this enlarged portion, the tube 9 carries a support member 12 of generally tubular form having an outwardly projecting flange 14 at one end, the flange abutting the enlarged part 11 of the tube. The flange 14 is fixed to the end of the casing, as by studs (not shown) so that the tube 9 and conducting rod 8 are supported coaxially with respect to the casing 4. An O-ring 18 forms a gasi and liquid-tight seal between the surface of the casing 4 around the opening and the adjacent face of the flange 14.

A current transformer 15 surrounds the tubular part 16 of the support member 12, and is protected by a cylindrical cover 17 the rim 19 of which fits over the outside edge of the flange 14, and a gasl and liquid-tight seal is formed between them by a further O-ring 20. The cover 17 is secured in position by a weathershield 21 fitted on to the outer end of the tube 9. The weathershield 21 comprises a plurality of separate collars, the innermost collar 22 comprising a stress cone and having a flange 23 which seals against the outer surface of the current transformer cover 17. The stress cone and the remainder 24 of the collars are formed of insulating material such as EPDM rubber and consist of a series of identical axially-overlapping dishes giving a corrugated outer surface to the weathershield so as to increase the creepage and flashover lengths.

The weathershield is terminated by a insulating cap 25 of the same material which is secured to the tube 9 and holds the assembly of collars in place. The overlapping portions of the dished collars 24 and stress cone collar 22 are sealed with a silicone grease. The cap 25 and collars 22, 24 are removable from the tube 9, and this permits the current transformer to be readily removed and replaced if this proves to be necessary.

The outer end of the stem 3.3 of the other contact 3 of the vacuum switch 1 is connected, via an electrically insulating coupling 30 and a lever 26, to a shaft 27 which is pivotally supported from the casing 4 by a bush 28 and is connected at its opposite end to a suitable switch-actuating mechanism (not shown). The coupling 30 incorporates a telescopic section held in the extended position by compression springs 29 which allow a degree of overmovement of the shaft 27 following closure of the contacts 2, 3 and permits a known pressure to be applied to the contacts in the closed position.

A metal collar 31 is fixed to the stem 3.3 of the movable contact 3, and carries a radial projection 32 terminating in a bulbous end portion 33. This fits into one end of a metal spring cylinder 34 having longitudinal slots 35 extending in an alternate fashion along it from opposite ends.

The inner surface of the cylinder is formed with an annular groove 40 into which the bulbous end portion 33 seats, and following the insertion of the end portion into the cylinder 34 a metal ring 36 is fitted around the cylinder over the groove to prevent withdrawal of the bulbous end portion therefrom whilst allowing a limited tilting movement of the cylinder 34 relative to the projection 32.

The bulbous end 37 of a further conducting rod 38 fits into the opposite end of the cylinder, which rod extends transversely outwards through the stub 6, and is held in position by a bushing 39 of similar construction to that supporting the rod 8, the cylinder also being capable of a degree of tilt ing movement relative to the rod.

The form of coupling between the collar 31, which is attached to the stem 3.3 of the movable contact 3, and the fixed conducting rod 38, permits opening and closing movement of the contact 3 to take place whilst, at the same time ensuring an adequate current transfer between the contact and the rod 38.

In use the casing is preferably filled with an insulating fluid, either in gaseous or liquid form.

A window 49 is provided above the lever 26 through which the latter can be viewed. The lever 26 and a part of the coupling 25 are provided with holes (not shown) which initially are arranged to align with each other when the contacts are closed, the alignment or misalignment of the holes being observable through the window. As the contacts wear, the holes, viewed when the contacts are closed, will be gradually displaced with respect to each other, thus giving an indicative of the amount of contact wear produced.

Claims

1. Electrical apparatus of the kind referred to wherein a first conducting member movable to a limited extent along a linear path carries a transverse projection terminating in a bulbous end, which fits into one end of a conducting cylinder, and a second conducting member carries a second bulbous portion which projects into the opposite end of the cylinder, the walls of the cylinder being slotted and of such diameter that they apply spring pressure against both bulbous portions whilst allowing tilting movement of the cylinder to take place on movement of the first conducting member.

2. Electrical apparatus according to Claim 1 wherein the wall of the cylinder is formed with longitudinal slots extending partly along it from opposite ends.

3. Electrical apparatus according to Claim 2 wherein the slots extend the greater part of the length of the cylinder alternately from opposite ends.

4. Electrical apparatus according to any preceding Claim wherein one of the bulbous portions is held in position within the cylinder by an annular locating groove formed at an appropriate position in the inner surface of the cylinder.

5. Electrical apparatus according to Claim 4 wherein an encircling band is disposed around the cylinder so as to secure said bulbous portion against withdrawal therefrom.

6. Electrical apparatus according to any preceding Claim incorporating an electrical switch wherein the cylinder provides an electrical connection between a movable contact of the switch and a fixed conductor.

7. Electrical apparatus according to Claim 6 wherein the electrical switch is a vacuum switch.

8. Electrical apparatus according to Claim 7 wherein the vacuum switch is accommodated within an outer casing containing an insulating gas or liquid.

9. Electrical apparatus incorporating means for transferring electric current between two relatively movable electrically conducting members substantially as shown in and as hereinbefore described with reference to Figures 1 to 3 of the accompanying drawings.