WO1994016450A1

WO1994016450A1 - Compact busbar assembly

Info

Publication number: WO1994016450A1
Application number: PCT/FI1994/000017
Authority: WO
Inventors: Jyrki Mannio
Original assignee: Pielisen Oma-Keskus Oy
Priority date: 1993-01-15
Filing date: 1994-01-14
Publication date: 1994-07-21
Also published as: FI930155A0; SE9403007L; DE4490058B4; SE513982C2; SE9403007D0; DE4490058T1; FI92268B; FI92268C

Abstract

The present invention relates to a busbar assembly for low-voltage distribution centers, said assembly having such a small-width construction that it can be vertically mounted between, e.g., two adjacent sections of the switchgear. Such a busbar assembly requirs no special busbar gutter, reduces the routing length of cables to switchgear outgoing terminals by 50 % and causes no blockage to the exiting cables. The basic principle of the busbar assembly is implemented in the superimposed stacking of the busbars. Owing to the slanted contact surfaces (6), all connections are readily accessible and the low-cost lug terminations (9) can be placed to the same level, whereby a high density of connections is attained. To the end of improving the protection of the busbars against accidental contact, it can be coated on all sides except the electrical contact areas with an insulating material whose proper choice can also improve the current-carrying capacity of the busbar by approx. 25 %.

Description

Compact busbar assembly

The present invention relates to a busbar assembly which is suited for use in electrical distribution centers and has such a small-width construction that permits its ver¬ tical mounting between the sections of the distribution center.

Typical applications of the busbar assembly are found in distribution centers having a dead-front or splash-proof construction. The assembly is also most suitable for use as the vertical busbars of vault-mounted distribution centers.

Conventionally, the busbars of dead-front and splash- proof distribution centers are located horizontally to the upper or lower end of the center, opposite to the exit space of the branch circuit cables (see Fig. 1) . Since conductors cannot be bent past the busbars in a practical installation, the result is that only one end of the distribution center is available for the exit of the cables. This drawback causes extra cable costs in situations in which the direction of the exiting cable must actually be reverted.

In general, a busbar assembly located at one end of the distribution center necessitates longer routing of the cables to reach equipment situated at the opposite end of the center.

The busbar assembly according to the invention achieves savings better than 50 % in the routing lengths of the main branch circuit cables.

The benefits and construction principle of the busbar assembly according to the invention will be evident from Figs. 1-7 in which Fig. 1 shows a conventional distribution center widely used today in which the busbars 1 are oriented horizon¬ tally at the lower end of the distribution center, whereby the exit for the branch circuit cables becomes blocked, thus requiring long routing of cables from the busbars to the equipment 2 at the upper end equipment of the distribution center,

Fig. 2 shows a distribution center having the busbar assembly 3 according to the invention oriented vertically between the sections of the distribution center, whereby savings better than 50 % in the routing lengths of the main branch circuit cables are gained over the cabling of the conventional distribution center shown in Fig. 1,

Figs . 3 and 4 show busbar cross sections 4 and 5 conven¬ tionally used today that in an adjacent alignment require a busbar gutter width of 250-300 mm, which typically must be protected by separate covers,

Figs. 5 and 6 show busbar cross sections according to the invention in a single-sided (Fig. 5) and two-sided (Fig. 6) version, both having the basic principle of the busbar cross section implemented in the form of a slanted contact surface 6 incorporating a slot 7 suited to accommodate the head of a connection bolt 9, whereby the cost of the lug connection illustrated in Fig. 5 amounts to approx. 10 % only of the cost of the clamping method shown in Fig. 3, and

Fig. 7 shows the pairwise superimposed stacking of the busbars according to the invention, whereby two-sided busbars are correspondingly installed singly stacked in a manner having a supporting insulator 11 and a busbar pair alternately placed onto long support screws 10, after which the entire busbar assembly is finally covered with an insulator sheet 12 and the assembly is tightened with nuts 13.

As is evident from Fig. 7, the connections are obliquely stepped so that each connection is accessible even when two connections are located at the same level. This facility is attained by orienting the connection bolts to both sides of the busbar assembly.

Further evident from Fig. 7 is the method of covering all current-carrying capacity ranges from 250 A to 1250 A using only three different busbar cross sections. The higher current-carrying capacities are achieved by paralleling adjacent busbars 15 with a conducting strap 14.

In a multisection distribution center the busbar assembly is located to every second conductor gutter between the sections of the center and then connecting the corre- sponding busbars of the assemblies to each other with conducting straps or conductors. In a vault-mounted dis¬ tribution center the busbar assemblies are placed in a similar manner to every second conductor gutter, while in a vault-mounted distribution center of conventional con- struction the busbars are located in each conductor gutter. Thus, the busbar assembly can be installed in all cases to either side of a section.

For improved protection against arcing, the busbar except its slanted contact areas can be coated with an insulating material such as, e.g., a dual epoxy resin coating 8. The coating of the busbars can be advanta¬ geously applied in a manner that improves the cooling of the busbars, thus permitting loading the busbars by up to approx. 25 % above that of smooth metallic busbars. To secure the electrical contact, the slanted contact surface can be grooved.

The busbar assembly according to the invention achieves the following benefits:

- The size of the distribution center and simultaneously the price of its frame structure is decreased by approx. 20 %. - Shorter routing of conductors from the busbar assembly to the equipment reduces the routing lengths of the main branch circuit cables by approx. 50 %.

- Both ends of the distribution center are accessible for exiting cables. - A busbar assembly situated at a standard location promotes the standardization of distribution centers and use of standard length conductors.

- The lower cost of connecting lugs reduces connector costs by approx. 50 %. - Sided cross section of the busbar is stiffer and has improved cooling characteristics over, e.g., a round busbar.

- Connections to the busbar require less space as they can be located to the same level. Yet, each connection is readily accessible, because the connections are arranged slanted in a stepwise manner.

- Owing to the paralleling facility, the selection of required busbar sizes can be reduced. E.g., using three different busbar sizes only, current-carrying capacities from 250 A to 1250 A can be covered without any need for overdimensioning.

- Only a single size of busbar insulator is required to serve all current-carrying capacities.

- The width of the busbar assembly is constant for all current-carrying capacities. This helps the standardization of other distribution center elements.

Claims

Claims :

1. A compact busbar assembly formed by one or multiple one-sided (Fig. 5) or two-sided (Fig. 6) busbars assembled onto supporting insulators (11) into a parallel busbar assembly, c h a r a c t e r i z e d in that the cross section of the one-sided busbar (Fig. 5) has one, and correspondingly, the cross section of the two-sided busbar has two contact surfaces (6) essentially slanted toward the bottom of the distribution center, each incorporating a mounting slot (7) for the head of a connection bolt (9) or equivalent connector member.

2. A busbar assembly as defined in claim 1, c h a r - a c t e r i z e d in that, to the end of achieving improved arcing protection and current-carrying capacity, the outer surfaces of the busbar element excepts its slanted contact surfaces are coated with an insulating material.

3. A busbar assembly as defined in claim 1, c h a r ¬ a c t e r i z e d in that to the end of achieving improved electrical contact the slanted contact surface (6) of the busbar element is grooved.

4. A busbar assembly as defined in claim 1, c h a r ¬ a c t e r i z e d in that the adjacent busbars of the assembly can be connected in parallel by a connecting strap (14) to the end of achieving improved current- carrying capacity.

5. A busbar assembly as defined in claim 1, c h a r ¬ a c t e r i z e d in that to the external width dimen¬ sions of the one-sided (15) , and correspondingly, the two-sided busbar elements (Fig. 6) are identical for all current-carrying capacities, while the other dimensions and shapes of the of the busbar elements are varied to the end of achieving improved current-carrying capacity.

6. A busbar assembly as defined in claim 1, c h a r ¬ a c t e r i z e d in that each one-sided, and corre¬ spondingly, two-sided busbar element has a separate supporting insulator, whereby a required number of busbars can be installed as desired.