Connection to local utility

[sanalv]

Dear all:

We are installing a generating center to supply loads to an industrial Plant. The generating center is gas internal combustion motors based, totaling 21 MW. Generators terminal voltage is 4.16 kV, there are installed step up transformers to bring voltage to 34.5 kV.

Our 4.16 and 34.5 kV switchgears have circuit breakers and up to date microprocessor based protective relays. Motor and generators are well protected complying all European directives.

Our client wants to connect the local generation and the load to the local utility using a standard 34.5 kV recloser (with reclosing option disabled), our Plant control shall command tripping and closing of the recloser.

I would like to hear comments about this recloser application.

Thanks in anticipation

 

[dpc]

As long as the recloser has adequate interrupting ratings for the maximum possible fault current (in either direction), it should work OK. Of course you will need synchronizing equipment and appropriate protective relaying for the interface, in addition to the normal overcurrent functions provided by the recloser controller. The recloser must be capable of accepting a remoter trip (and close) signal. And you must have a reliable source of control power to operate the recloser.

We use reclosers for utility tie connections where the fault currents allow. But normally at 34.5 kV we generally end up with a circuit breaker.

 

[davidbeach]

The recloser would also have to be rated for synchronizing duty, which I doubt it would be. You will have up to twice nominal voltage across the open contacts; does the recloser have a dielectric withstand rating of something well over 69kV? Probably not.