345kV Variable Shunt Reactor Protection

[powereng1]

A client will be installing a set of two 50-100 MVAR Reactors. I do not have much experience on reactor protection but I do have a few references from SEL that I can use. The Reactor will be connected to a 345kV bus (along with a synchronous breaker), the low side of the reactor will be tied to ground. For the primary protection I am planing on using a SEL-487E (see attachment)and I planning on using a SEL-387 for backup protection. I am having difficulty with selecting the proper CT ratings and rations for the back up protection, I do not want to violate the 387E max tap ratio which is 7.5 (client really likes using the 387E for their backup). The fault current at this site is close to 43kA.

Can anyone take a look at my Diagram and see any potential issues? Any suggestions are welcome.

Thanks

 

[collies99]

I see a zone within a zone. It may be advsntageous to overlap the CT on the high side.

 

[Marmite]

The attached document might be useful. There is a list of references at the end which will also give you more information.
Regards
Marmite

 

[davidbeach]

Not really answering the question, but it seems overly complex to pair a 487E with a 387E. They're different enough that you have to start over from scratch for the second relay. The finished installation will be more reliable with just one relay type.

 

[bacon4life]

It is hard to read any of the text; is the 3rd relay shown an SEL 351? If the 3rd relay provides adequate backup protection for faults between the breaker and the reactor, are the Reactor CT's a better ratio for the 387E?

 

[powereng1]

@bacond4life, yes the 3rd relay is a 351S it will provide over-current protection as well as BF, what would you conciser as adequate protection for this application? I am not 100% sure what you meant by "are the Reactor CT's a better ratio for the 387E". The Reactor CT's will be C800, 600:5 - 150:5.

Also, can any one confirm something I read in a sel application paper, "if the reactor neutral is directly grounded, the wye-connected reactor group has identical positive, negative and zero-sequence impedances.

Thanks for all the help.