GB2187034A

GB2187034A - Electrical distribution board

Info

Publication number: GB2187034A
Application number: GB08604432A
Authority: GB
Inventors: Ivan Frank Smart
Original assignee: George Ellison Ltd
Current assignee: George Ellison Ltd
Priority date: 1986-02-22
Filing date: 1986-02-22
Publication date: 1987-08-26
Anticipated expiration: 2006-02-22
Also published as: GB8604432D0; GB2187034B

Abstract

A distribution board includes a bonded laminated bus structure for connecting individual circuit breakers to a polyphase supply. The laminate includes a separate conductive sheet (e.g. 14) for each phase. These sheets are separated by and sandwiched between insulating sheets 17, 18 which are of larger superficial dimensions than the conductive sheets. Strips (21) of insulating material are sandwiched between the insulating sheets to enclose the edges of the conductive sheets except at one end of the bus structure. Here, tabs (24, 26, 27) on the respective conductive sheets are exposed. These tabs are reinforced by their being bonded to tabs (like 31) on the insulating sheets and additional strips (29) sandwiched between the tabs (31). <IMAGE>

Description

SPECIFICATION Electrical distribution board This invention relates to an electrical distribution board ofthe kind including a polyphase bus structure where inputs to the board are connected to a plurality of circuit breakers or other switch devices (hereinafter referred to as "circuit breakers").

It has already been proposed to construct a polyphase bus structure using a laminated assembly of conductive and insulating sheets; see, for example, GB 1,220,074. With such a structure, however, the conductive sheets have connectors attached thereto (by welding, brazing or otherwise) and the connectorswhich enableinputsto be connected must be well spaced from the edges ofthe laminated assembly.

The object of the present invention is to provide a distribution board including a laminated bus structure in which connections can be made directly to the edges of the conductive sheets, without attached connectors.

In accordance with the invention the distribution board incorporates a bonded laminated bus structure comprising a plurality of conductive sheets separated by and enclosed between insulating sheets, the sheets being of elongated form with the insulating sheets wider than the conductive sheets, insulating strips disposed between the insulating sheets along the longitudinal edges ofthe conductive sheets, so as to enclose the conductive sheets at their longitudinal edges, further strips of insulating material disposed between the insulating sheets at one end ofthe structure so as to enclose the sheets at that end, openings in the laminated bus structure arranged to expose selected areas ofthe conductive sheets for the connection of the circuit breakers thereto, tabs on the conductive sheets projecting from the opposite end ofthe laminated bus structure, the tabs on the conductive sheets being disposed at different positions across the width of the structure, tabs on the insulating layers projecting between said tabs on the conductive sheets and each overlapping the tabs on the conductive sheets and strips of laminated material disposed between the tabs on the conductive sheets.

An example ofthe invention is shown in the accompanying drawings in which:- Figure lisa front elevation of a distribution board; Figure2 is an end elevation of the board shown in Figure 1; Figure 3 is a front elevation of a laminated bus structure forming a part of the board shown in Figure 1 onalargerscale; Figure 4 is a fragmentary sectional view of one end of the bus structure of Figure 3; Figure 5is an enlarged section onthe line 5-5 in Figure 3; and Figure 6is an enlarged section on the line6-6in Figure 1.

As shown in the drawings the distribution board includes a laminated bus assembly 10 mounted on a supporting framework 11 A plurality of circuit breakers, of which but two 12, 13 are shown, are provided, each ofthese being supported atone end by the assembly 10 and atthe other end bythe framework 11.

The laminated busassembly 10includesthree conductive layers 14,15,16 arranged in a spaced parallel arranged and having interposed between them two insulating layers 17,18. Two outer insulating layers 19, 20 are also provided.

Aswill beobservedfrom Figure 3,the bus assembly is ofelongate form, the insulating layer(17 to 20) being widerthan the conductive layers. Six flat strips 21 of insulating material lie alongside the longitudinal edges ofthe conductive layers between the insulating layers.Atoneendoftheassembly,the conductive layers 14,15, 16 are progressively shorter than one another and all are shorterthan the insulating layers. A narrow insulating strip 22 lies between the insulating layers adjacent the layer 16 and progressivelywiderstrips23and24aresimilarly associated with the conductive layers 15 and 14.

At the other end of the bus assembly, the three conductive layers 14,15, are provided with respectiveflattabs 25,26, 27 which projectto provide input terminals for the bus assembly. These tabs are mutually offset from one another across the width ofthe assembly. Specifically, the tab 25 is at the left hand side, tab 26 in the middle and tab 27 at the right hand side. Each tab has a width one-third the width ofthe conductive layers. Each ofthe insulating layersi7to 20 is shaped as shown in Figure3and hastwotabs likethetabs 19awhich overlapthetabs on the conductive sheets.

Figure 4 and 5 showthisterminal end construction in detail and it will be seen that, in the plane ofthe conductive sheet 14 there are strips of insulating material 28,29,30 which serve to enclose those parts ofthe edges of layer 14 which fall between the two adjacent insulating layers 19 and 17. Another piece 31 of insulating materials lies between the tabs 1 9a between which no conductive layer lies. Similar arrangements are provided in respect of the layers 15 and 16 and the shapes and positions ofthe added insulation material attheterminal end will be apparent without any detailed description.

For making connections between the conductive layers and the inputs of the circuit breakers, each of the conductive layers is formed with a pattern of holes. Where a connection is required to a particular layer thins layer has a relatively small hole 14a, 14b (see Figure 4). Where a connection is required to another of the conductive layers the particular layer has a larger hole and in this hole a flat insulating washer32 is inserted. In the exampleshownthe diameter of these larger holes is greaterthan their longitudinal spacing so that instead of a pairof circularholes,a singlefigure-8shaped hole is formed. The washers 32 are appropriately cut away to fit.

The assembly 10 is laid up in a suitable jig, one layer at a time, with adhesive fabric laid between the sheets. Thus, for example, insulating layer is placed in the jig first, covered by an adhesive sheet and this in turn is covered bytheconductive layer 15 and all the strips, washer, tabs etc. required to surround it, another adhesive sheet is laid overthis and then the next insulating sheet and so on. When thewhole assembly is laid up, the adhesive is cured in an oven whilst a clamping force is applied to urge the layers together.

The resulting laminate is very strong and its structure ensures that there are no short arc paths between the conductive layers.

Figure 6 shows the arrangement by means of which the circuit breakers are mounted. Three internally threaded conductive sleeves 40,41,42 are employed. These are bolted at one end to the conductive sheets (using the small holes) and are of different lengths such thattheirother ends are coplanar. The terminals of the circuit breaker are directly bolted to these sleeves. The washers 32 ensure good insulation of these sleeves and bolts etc.from the conductive layers otherthan the one to which each is intended to be connected.

The terminal end of the bus assembly provides three conductive tabs to which electrical connections can readily be made. The projecting tabs are strengthened by the surrounding insulation, which also serves to separate from one another connectors used for making electrical connections to the tabs.

Claims

1. Adistribution board incorporating a bonded laminated bus structure comprising a plurality of conductive sheets separated by and enclosed between insulating sheets, the sheets being of elongated form with the insulating sheets widerthan the conductive sheets, insulating strips disposed between the insulating sheets along the longitudinal edges of the conductive sheets, so as to enclose the conductive sheets at their longitudinal edges, further strips of insulating material disposed between the insulating sheets atone end ofthe structure so asto enclose the sheets at that end, openings in the laminated bus structure arranged to expose selected areas ofthe conductive sheets forthe connection of the circuit breakers thereto, tabs on the conductive sheets projecting from the opposite end ofthe laminated bus structure,the tabs on the conductive sheets being disposed at different positions across the width of the structure,tabs on the insulating layers projecting between said tabs on the conductive sheets and each overlapping the tabs on the conductive sheets and strips of laminated material disposed between the tabs on the conductive sheets.

2. Adistribution board substantially as hereinbefore described with reference to the accompanying drawings.