1. Design Considerations
The word busbar, derived from the Latin word omnibus ('for all'), gives the idea of a universal system of conveyance. In
the electrical sense, the term bus is used to describe a junction of circuits, usually in the form of a small number of
inputs and many outputs. 'Busbar' describes the form the bus system usually takes, a bar or bars of conducting material.
In any electrical circuit some electrical energy is lost as heat which, if not kept within safe limits, may impair the
performance of the system. This energy loss, which also represents a financial loss over a period of time, is proportional
to the effective resistance of the conductor and the square of the current flowing through it. A low resistance therefore
means a low loss; a factor of increasing importance as the magnitude of the current increases.
The capacities of modern-day electrical plant and machinery are such that the power handled by their control systems
gives rise to very large forces. Busbars, like all the other equipment in the system, have to be able to withstand these
forces without damage. It is essential that the materials used in their construction should have the best possible
mechanical properties and are designed to operate within the temperature limits laid down in BS 159, BS EN 60439-
1:1994, or other national or international standards.
A conductor material should therefore have the following properties if it is to be produced efficiently and have low
running costs from the point of view of energy consumption and maintenance:
a) Low electrical and thermal resistance
b) High mechanical strength in tension, compression and shear
c) High resistance to fatigue failure
d) Low electrical resistance of surface films
e) Ease of fabrication
f) High resistance to corrosion
g) Competitive first cost and high eventual recovery value
This combination of properties