when I was inspecting a medium volt

[144x]

when I was inspecting a medium voltage switchgear I noticed that in some parts the silver plated buses are in direct contact with copper busbars.when I commented, they said that they have sold many of this equipment without having heard of a problem.any idea on how this bimetalic junction works?

 

[gordonl]

Silver on copper in itself should be fine, but if this is a current carrying junction it partially defeats the purpose. (They should both be plated in that case)

 

[144x]

but the anodic index of the two metals does not let them to be in direct contact.

 

[CHDean]

Most manufactures usually ring plate the joints as a minimum but silver plated copper to bare copper connections shouldn't cause any excess heating. It is done in the majority of assemblies 600V=/-

 

[Subbldr]

Silver plating of copper bus is very common in 4-25 KV switchgears(at least where I work). In my 15 plus years of Substation experience, I've yet to see a problem develop with copper to silver plated copper connections. Although I don't see the logic in plating only one side of the connection, I'm quite sure that properly prepared connections pose few if any problems.

 

[jbartos]

Suggestion: Silver as well as copper is subject to oxidation. Therefore, the connection must be tight for all combinations, i.e.
copper on copper
silver on copper
silver on silver

 

[Jerry123]

This silver plating is also common in newer ASCO ATSs. They use the plating with a very expensive conductive grease.