Utility main switch re-closure

10.5Kv to 220KV supply? Think about it! The higher voltage will melt your gen sets and some.

Are you trying to parallel connect two (or more) 10.5kV single phase generators to the local single phase 220kV supply (using, I am assuming, a 10.5-220kV step up transformer) using a single recloser?

What is the supply current?

I am assuming you are looking at a recloser that is designed for this (not all of them are).

jack, yes, we are connecting fifteen 10.5KV gensets to a 220KV grid via step up transformer, the 220kV main switch to the transmission line will attempt to reclose once for any line problem, if this reclosure affort fails then the switch will stay tripped... this is the requirement from local grid.

We are concerned this one time reclosure (within 0.5s) will damage the alternator rectifier, however, such single line re-closure is quite commonly required by grid company worldwide... so we doubt whether truely it can damage the alternator.

I have not had any experience trying to grid tie this many generators (of this high voltage) to the network. Previously I have done it using a Siemens feeder management relay controlling a vacuum interrupter switch on the HV side (before the transformer), but that was as a fully protected and controlled substation designed for parallel and island mode operation, and the generators were only 415V.

I think the generator company you got the generators from would be the best place to start asking these questions, and also run it past the recloser manufacturer. They should have the experience to answer these sort of special application questions.

AtLeast that is what I would do.

Jack gives proper advice the entire gen system regulator speed control all of it is at risk if the units are not designed for the application re closures can be real blast , figuratively and literally!

Jon