Busbar Systems

Busbar Systems

General data

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Siemens LV 10 · 2014

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Overview

The use of busbar systems with their versatile rail-adaptable

connection, switching and installation devices is an ideal and

cost-effective electrotechnical enhancement of modern distribu-

tion boards due to their small footprint, compact design and

quick assembly contacts. Mounting is implemented on longitu-

dinal stays. The busbar spacing is 60 mm.

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Benefits

Notable cost reduction compared to conventional installation in

switchgear and control cabinets due to the following reasons:

• Mechanical fixing and electrical contacting in a single step

• No access wiring and fewer busbar terminals used

• Double use of the busbar space

• Clear arrangement

• Straightforward replacement of individual devices or whole

combinations

• High operational safety through finger-safe cover of the adapt-

ers and device holders

All the above advantages are felt especially in cases where

many tap-off units of the same performance range are required.

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Application

8US busbar systems are used for the direct busbar-mounting of

current-limiting devices (protective devices) such as fuse switch

disconnectors and circuit breakers as well as complete load

feeders.

8US busbar systems are designed for horizontal mounting of the

busbars.

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Design

8US busbar systems with 60 mm busbar center-to-center spac-

ing as well as flat copper profiles have become firmly estab-

lished on the world market.

The permissible busbar temperature is decisive when dimen-

sioning the busbars. The busbar temperature is dependent on

the current and the current distribution, on the busbar cross-sec-

tion and the busbar surface, on the position of the busbars, con-

vection and the ambient temperature. The values stated in the

following table can only be considered as guide values because

the conditions vary with each location. The values are based on

continuous current over the whole busbar length.

The busbar runs prove most advantageous when the infeed is

centrally located and the load is distributed symmetrically on

both sides.

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Function

Short-circuit strength

The short-circuit strength of the busbar system is dependent on

the distance of the busbar supports and on the busbar cross-

section.

The short-circuit strength of the whole system is dependent on

the short-circuit strength of the busbars and of the adapters with

circuit breakers or switch disconnectors. If one of these values

is lower than the prospective short-circuit current at the installa-

tion site, a current-limiting protective device has to be mounted

upstream of the 8US busbar system. This may also be mounted

as a feeder circuit breaker on the busbar system itself.

Longitudinal stays

Busbar supports, three-phase

Cu busbars

Terminals

Supports for blanking covers

Blanking covers

Supports

Touch protection cover

Busbar supports, single-phase

I201_13633