GB2105921A

GB2105921A - Electric distribution systems

Info

Publication number: GB2105921A
Application number: GB08225720A
Authority: GB
Inventors: Nicholas Paul Allen; Alan Lister Kidd
Original assignee: Dorman Smith Switchgear Ltd
Current assignee: Dorman Smith Switchgear Ltd
Priority date: 1981-09-11
Filing date: 1982-09-09
Publication date: 1983-03-30
Also published as: GB2105921B

Abstract

In an electric distribution system of the kind comprising a plurality of substantially rigid electric busbars (1) arranged in substantially parallel relationship and transversely spaced apart, a busbar support arrangement comprises a pair of substantially rigid elongate members (4) of electrically insulating material extending transversely across and on opposite sides of the transversely spaced busbars, the insulating members having, alongside each busbar, apertures (5) that are in substantially axial alignment. The insulating members are clamped to the busbars by at least one pin (6) which extends through each pair of aligned apertures in the insulating members, the pin having at at least one of its ends a head (7) of such a shape having regard to the shape of the aperture in the adjacent insulating member that the head bears against the adjacent insulating member and the pin is thereby prevented from movement in one direction substantially parallel to the pin axis and being so shaped between its ends as to provide at least one shoulder extending transversely of the pin. At least one bolt (9) extends transversely through a hole or through aligned holes in and is clamped to the busbar, which bolt so engages the shoulder or shoulders of the pin or pins that movement of the or each pin in the other direction substantially parallel to the pin axis is prevented. <IMAGE>

Description

SPECIFICATION Electric distribution systems This invention relates to electric distribution systems of the kind comprising a plurality of substantially rigid electric busbars or other elongate electric conductors arranged in substantially parallel relationship and transversely spaced apart, all such substantially rigid elongate electric conductors employed in an electric distribution system of this kind hereinafter, for convenience, being including in the generic term "busbar". The invention is especially, but not exclusively, concerned with an electric distribution system comprising four busbars, one for each phase and one constituting a neutral busbar.

Each busbar may be a single substantially rigid elongate electric conductor or one or more than one of the busbars may be two or more transversely spaced, substantially rigid elongate electric conductors, electrically connected in parallel.

It is an object of the present invention to provide a simple and inexpensive arrangement for supporting the busbars of an electric distribution system of the aforesaid kind against the effects of forces to which the busbars are likely to be subjected under short circuit conditions.

According to the invention the busbar support arrangement comprises a pair of substantially rigid elongate members of electrically insulating material extending transversely across and on opposite sides of the transversely spaced busbars of the distribution system, the transversely extending insulating members having, alongside each busbar, apertures that are in substantially axial alignment; and, clamping the insulating members to the busbars, at least one pin extending through each pair of aligned apertures in the transversely extending insulating members, the pin having at at least one of its ends a head of such a shape having regard to the shape of the aperture in the adjacent insulating member that the head bears against the adjacent insulating member and the pin is thereby prevented from movement in one direction substantially parallel to the pin axis and being so shaped between its ends as to provide at least one shoulder extending transversely of the pin and, extending transversely through a hole or through aligned holes in and clamped to the busbar, at least one bolt which so engages the shoulder or shoulders of the pin or pins that movement of the or each pin in the other direction substantially parallel to the pin axis is prevented.

Preferably, two pins extend through each pair of aligned apertures in the transversely extending insulating members, the pins being introduced into the apertures from opposite sides of the insulating members and having, at the trailing end of the pin, a head of such a shape having regard to the shape of the aperture in the adjacent insulating member that the head bears against the insulating member and the pin is thereby prevented from further movement in the direction of insertion of the pin.In this case, preferably also, two bolts extend through holes or aligned holes in and are clamped to the busbar, the holes or aligned holes being spaced in the axial direction of the pin or pins, with one bolt engaging the shoulder of one pin to prevent movement of the pin in the other direction substantially parallel to the pin axis and the other bolt engaging the shoulder of the other pin to prevent movement of the pin in the other direction substantially parallel to the pin axis.

Where two pins are employed, preferably they are substantially identical to one another and, in a preferred embodiment, each comprises a cadmium plated steel strip which is transversely folded at at least one position between its ends to form a shoulder and which, at one of its ends, has an integral head which extends transversely beyond the side edges of the strip.

In an alternative arrangement, a single clamping pin may be employed in association with at least one of the busbars and, in this case, the pin has, at one end, a head which will prevent axial movement of the pin in one direction and, at its other end, a head which will prevent axial movement of the pin in the other direction, the aligned apertures in the transversely extending insulating members being of such a shape that they will permit passage of the heads of the pin when the heads are appropriately aligned with respect to the apertures and which, when the pin is partially rotated about its axis, will not permit passage of the heads, the pins therefor being prevented from moving in both axial directions by the transversely extending insulating members; a single bolt only is then required to clamp the pin to the busbars.

Where a busbar comprises two substantially~rigid elongate electric conductors, preferably the aligned apertures in the transversely extending insulating members are so positioned that the pin or pins passes or pass between the conductors. Where a busbar comprises three or more substantially rigid electric conductors, preferably aligned apertures in the transversely extending insulating members are so positioned that a pin or pins extends or extend between each adjacent pair of electric conductors, the pins being clamped to the conductors of the busbar by the same bolt or bolts.

The arrangement of the present invention has the important advantages that it makes effective use of the material of the transversely extending insulating members by ensuring that, under short cirucit conditions, each member is stressed principally in the tension-compression modes. Another advantage lies in the fact that the amount of live parts extending beyond the limits of the busbars themselves is insignificant.

Although the arrangement of the present invention is especially suitable for use with busbars in which the or each conductor is of substantially rectangular transverse cross-section, it is to be understood that the invention is not restricted to use with busbars of this shape and the arrangement can be employed in distribution systems in which the busbars are of non-rectangular transverse crosssectional shape.Furthermore, although it is preferred that the faces of the busbars against which the transversely extending insulating members abut lie in a substantially common plane, it is to be clearly understood that the invention is not restricted to use with a distribution system in which the busbars are so arranged and distribution systems in which these suqaces of busbars do not lie in th-- same planes can be accommodated by suitable chei;;ri6 or local thickening of the transversely extending insulating members, or by the use of separate packing members of electrically insulating material.

The invention is further illustrated by a Gescription, by way of example, of a preferred distribution system with reference to the accompanying drawings, in which: Figure 1 is a fragmenta! front view of the preferred distribution system; Figure 2 is a fragmental side view of the system shown in Figure 1, with the bolts and nuts removed for clarity; and Figures 3,4 and 5, respectively, are plan, side and end views of a pin employed in the arrangement shown in Figures 1 and 2.

Referring to Figures 1 and 2, the electric distribution system comprises four busbars 1, one for each phase and one constituting a neutral busbar. Each phase busbar comprises two transversely spaced, substantially rigid electric conductors 2, electrically connected in parallel. The neutral busbar comprises a single rigid conductor 3. Each conductor 2, 3 is of substantially rectangular cross-section and the conductors are arranged with two opposite faces lying in common planes. The busbar support arrangement comprises a pair of rigid elongate members 4 of insulating material extending transversely across, and on opposite sides of, the busbars 1. The insulating members 4 have aligned apertures 5 positioned between the conductors 2 of the phase busbars and alongside the conductor 3 of the neutral busbar.

Each busbar 1 is clamped to the insulating members 4 by two pins 6 (shown in more detail in Figures 3, 4 and 5) which extend through the aligned apertures 5 from opposite sides of the insulating members. Each pin 6 has a head 7 which bears against one of the insulating members 4 to prevent movement of the pin in one direction parallel to the pin axis, and shoulders 8 extending transversely of the pin. Two bolts 9 pass through holes 10 in the busbars 1, each bolt engaging one shoulder 8 of each pin 6, to prevent movement of the pin in the other direction substantially parallel to the pin axis, thereby supporting the busbars on the insulating members 4.

Claims

1. In an electric distribution system of the kind comprising a plurality of substantially rigid electric busbars, as hereinbefore defined, arranged in substantially parallel relationship and transversely spaced apart, a busbar support arrangement comprises a pair of substantially rigid elongate members of electrically insulating material extending transversely across and on opposite sides of the transversely spaced busbars, the insulating members having, alongside each busbar, apertures that are in substantially axial alignment; and, clamping the insulating members to the busbars, at least one pin extending through each pair of aligned apertures in the insulating members, the pin having at at least one of its ends a head of such a shape having regard to the shape of the aperture in the adjacent insulating member that the head bears against the adjacent insulating member and the pin is thereby prevented from movement in one direction substantially parallel to the pin axis and being so shaped between its ends as to provide at least one shoulder extending transversely of the pin and, extending transversely through a hole or through aligned holes in and clamped to the busbar, at least one bolt which so engages the shoulder or shoulders of the pin or pins that movement of the or each pin in the other direction substantially parallel to the pin axis is prevented.

2. A busbar support arrangement as claimed in Claim 1, wherein two pins extend through each pair of aligned apertures in the transversely extending insulating members, the pins being introduced into the apertures from opposite sides of the insulating members and having, at the trailing end of the pin, a head of such a shape having regard to the shape of the aperture in the adjacent insulating member that the head bears against the insulating member and the pin and is thereby prevented from futher move ment in the direction of insertion of the pin.

3. In an electric distribution system of the kind comprising a plurality of substantially rigid electric busbars, as hereinbefore defined, arranged in substantially parallel relationship and transversely spaced apart, a busbar support arrangement comprises a pair of substantially rigid elongate members of electrically insulating material extending transversely across and on opposite sides of the transversely spaced busbars, the insulating members having, alongside each busbar, apertures that are in substantially axial alignment; and, clamping the insulating members to the busbars, two pins which extend through each pair of aligned apertures in the insulating members, the pins being introduced into the apertures from opposite sides of the insulating members and having at the trailing end of the pin a head of such a shape having regard to the shape of the aperture in the adjacent insulating member that the head bears against the adjacent insulating member and the pin is thereby prevented from further movement in the direction of insertion substantially parallel to the pin axis, each pin being so shaped between its ends as to provide at least one shoulder extending transversely of the pin, and, two bolts which extend transversely through holes or through aligned holes in and are clamped to the busbar, the holes or aligned holes being spaced in the axial direction of the pins, with one bolt engaging the shoulder of one pin to prevent movement of the pin in the other direction substantially parallel to the pin axis, and the other bolt engaging the shoulder of the other pin to prevent movement of the pin in the other direction substantially parallel to the pin axis.

4. A busbar support arrangement as claimed in Claim 2 or Claim 3, wherein the two pins are substantially identical to one another and, each comprises a cadmium plated steel strip which is transversely folded at at least one position between its ends to form a shoulder and which, at one of its ends, has an integral head which extends transversely beyond the side edges of the strip.

5. A busbar support arrangement as claimed in Claim 1, wherein a single pin is associated with at least one ofthe busbars and, the pin has, at one end, a head which will prevent axial movement of the pin in one direction and, at its other end, a head which will prevent axial movement of the pin in the other direction, the aligned apertures in the insulating members being of such a shape that they will permit passage of the heads of the pin when the heads are appropriately aligned with respect to the apertures and which, when the pin is partially rotated about its axis, will not permit passage of the heads, the pins therefore being prevented from moving in both axial directions by the insulating members,

6. A busbar support arrangement as claimed in any one of the preceding Claims, wherein at least one busbar comprises two substantially rigid elongate electric conductors, and wherein the aligned apertures in the insulating members are so positioned that the pin or pins passes or pass between the conductors.

7. A busbar support arrangement as claimed in any one ofthe preceding Claims, wherein at least one busbar comprises three or more substantially rigid electric conductors, and wherein the aligned apertures in the insulating members are so positioned that a pin or pins extends or extend between each adjacent pair of electric conductors, the pins being clamped to the conductors of the busbar by the same bolt or bolts.

8. A busbar support arrangement substantially as hereinbefore described, with reference to, and as shown in, the accompanying drawings.