How Do You Design and Size a Busbar?

How Do You Design and Size a Busbar?

The way that a copper Busbar system performs and is designed has significantly changed following the introduction of the IEC 61439 switchgear and control standards, and this has had major implications on the way that people must think about the selection of a Busbar system. There are many areas that now differ to previous methods that design engineers have become accustomed to; therefore it is important that everybody in the industry is on the same page.

The location of the incoming cables and the position of the incoming protection device heavily affect the decision regarding where to put the Busbar, and the layout of the assembly, position of devices and Busbar cover requirements are all determined by the form rating. The size of the enclosure will of course be ultimately dependent upon both the form rating and the Busbar system fitting!

So what is the current rating? The total load significantly impacts the size of the Busbar, therefore this must be pre-calculated and the IEC 61439 standards must be took into consideration, as a rating of 125% on the full load current is sometimes required depending on the circumstances. This knowledge of the current loadings will also mean that you can calculate the total watt loss, and this has a direct impact on the temperature rises within a particular enclosure.

If cables are oversized and too large to terminate on a Busbar system, then this can be problematic for any contractor, therefore when connecting conductors to a Busbar design engineers need to be aware of any potential differences when it comes to the Busbar adaptors or terminals. Finally, design engineers have to also be aware of the fault rating from the start, due to the obvious possibility of a high-fault current being destructive.

Further information is available online on the new changes to the designing and sizing of busbars, and once everybody is on the same page it will be very beneficial to the industry!

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