Why Are High Current Busbars Typically Nickel Plated?

[Starwatcher16]

Why do busbars rated for high current have nickel plating? DOes it have something to do with the skin effect?

 

[mgb_phys]

I would have thought as an anti-corrosion measure, or to stop you generating an electrochemical cell if you have to join any other metal contact to the copper.

 

[vk6kro]

I would have thought as an anti-corrosion measure, or to stop you generating an electrochemical cell if you have to join any other metal contact to the copper.

I'd agree with that.

Skin effect is something that happens when the current in a conductor is changing direction rapidly as in high frequency transmitting antennas. The current crowds towards the outside of the conductor and flows in the outer layer more than in the centre. This makes the conductor have more resistance than it does when DC current is flowing in it.

This would not be the case with Nickel plating which would be done with DC current.

 

[negitron]

This would not be the case with Nickel plating which would be done with DC current.

Nor for busbars used in electrical power systems. At 50 and 60 Hz, the skin effect is entirely negligible. Even at 400 Hz (used in aircraft) it can almost always be ignored.

 

[m.s.j]

In high current reasonably high temperature application the busbar silver and nickel plating is normal practice. At DC to 60Hz there is some controversy as to which plating is the best because while silver has the highest conductivity, but silver is more noble than copper so it will actually accelerate corrosion wherever the plating gets scratched. Nickel is used to 'flash' the copper bar material, prior to plating with silver, and thus prevent corrosion by 'sealing the surface of the copper, Then fine silver is used to do the final plate. Nickel and silver don't melt at a temperature under 1000 degrees. (Nickel = 1100 deg f, Silver = 1470 deg f)
It is helpful in providing and maintaining low resistance conductive joints. The effects of bus bar surface irregularities, the formation of non-conductive surface films caused by the local environment and temperature, and the formation of copper oxides can lead to bus joints.

These plating assists in:

-Stable contact resistance joints
-Minimizes the need for frequent maintenance
-Decreases overall downtime of equipment
-Minimizes maintenance costs
-Greatly reduce the risk of catastrophic failures.


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