You should probably megger it only at (at least) 1000V, making sure first that all voltage measuring devices, meters, relays, no-load resistor bank, etc, are disconnected and grounded at their side of their own fuses first. The feeder breakers should all be racked out completely. The same for the main rectifier breaker.
Is there a contract requirement that says otherwise?
It is Factory tested by siemens @ 6.9kv ac for 1min pre&post megger @1000v on bus through closed breakers
My test plan requests(client spec.) 2.5kv ac for 1min , on bus with breakers closed.
My query is why test with ac ??? when it is DC specific equipment ?
These are feeder's only there is not rectifier breaker in this sub.
In that case why not go ahead and test it at 2.5KV AC if the client wants it done that way. If it is only in principle a bus bar and closed breakers it is immaterial whether AC or DC is used for the test. In effect it is only a large chunk of conductor on insulators you are dealing with. Make sure nothing else is really connected as said above.
