Hi,
I wonder how a maximum current rating for wires and busbars are calculated.

How the maximum current rating for busbars are calculated, is there any standard for this.

I used a copper busbar for my motor connection. but i need how much max current can be passed through it, is there any calculation for it.

Thanks,
D

 

You could probably go 300 to 600 circular mils per amp but better off looking up a table where the aspect ratio of the shape is taken into account also.
However, sometimes buss bar is chosen for low resistance rather than max current handling. This would be especially true if you are working with a low voltage system where even relatively low resistance of a max current rated wire drops too much voltage and you need to improve on that.
Capacitor banks are better off wired with buss bars also to keep the overall ESR lower.

 

Calculate the cross section and use some reasonable current density. In addition to fusing, you need to consider voltage drop, heating, ambient temperature, etc...

 

There are AMPACITY AND SPECIFICATIONS TABLES which take the work out of it or you can, as suggested, do the math yourself. When I came off a buss, 3 phase 480 V Delta, I had to have a fused disconnect at the buss, followed by my drop using appropriately sized wire gauge for the drop and followed by another fused disconnect at the service location. I have no idea of your location but if they have electrical codes you may wish to consult them. When calculating a buss for service you also need to consider the material of the conductors, such as Copper or Aluminum. You also need to figure in temperature rise on the bus bar. I would just use a table for whatever alloy you want.

Ron