5 Copper Busbar Jointing Methods Posted Jun 17 2015by Edvardi n Energy and Powerwith 5 Comments 5 Copper Busbar Jointing Methods (photo redit! dona"mann#om$ Efcient joints in copper busbar conductors Efficient joints in copper busbar conductors can be made very simply by: 1# Bolting
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hen a conductor carries a current it creates a magnetic field which interacts with any other magnetic field present to produce a force. hen the
currents flowing in two adjacent conductors are in the same direction the force is one of attraction, and when the currents are in opposite directions a
repulsive force is produced.
In most busbar systems the current-carrying conductors are usually straight and parallel to one another.
*e orce produed by the two ondutors is proportiona" to the produts o/ their urrents#
/ormally in most busbar systems the forces are very small and can be neglected, but under short-circuit conditions, they become large and must be
ta!en into account together with the conductor material fibre stresses when designing the conductor insulator and its associated supports to ensure
ade0uate safety factors.
The factors to be taken into account may be summarised as follows:
1# tresses due to diret "atera" attrative and repu"sive /ores#
#n most cases the forces due to short-circuits are applied very suddenly. 1irect currents give rise to unidirectional forces while alternating currents
#n the case of a single-phase short-circuit, the forces produced are unidirectional and are therefore more severe than those due to a three-phase short-
circuit, which alternate in direction. The short-circuit forces have to be absorbed first by the conductor. The conductor therefore must have an
ade0uate proof strength to carry these forces without permanent distortion.
Copper satisfies this re0uirement as it has high strength compared with other conductor materials +Table 2 below.
/able * 0 /ypical relative properties of copper and aluminium
0roperties o Cu and l Copper(CW22$) luminium (1!&2) 3nits
Because of the high strength of copper, the insulators can be more widely spaced than is possible with lower-strength materials.
-etods o reducing conductor stresses
#n cases where there is a li!elihood of vibration at normal currents or when subjected to short- circuit forces causing damage to the conductor, the
following can he used to reduce or eliminate the effect(
a) Reduce the span between insulator supports.
This method can be used to reduce the effects of both continuous vibration and that due to short-circuit forces.
b) Increase the span between insulator supports.
This method can only be used to reduce the effects of vibration resulting from a continuous current. #t will increase the stresses due to a short-circuit
current.
c) Increase or decrease the fexibility o the conductor supports.This method will reduce the effects of vibration due to continuous current but has very little effect on that due to short-circuit forces.
d) Increase the conductor fexibility.
This can only be used to reduce the effects of vibration due to a continuous current. The short-circuit effect is increased.
e) Decrease the conductor fexibility.
This method will reduce the effects of vibration due to either a continuous current or a short-circuit.