Low impedance Busbar differential protection

[RRaghunath]

I am not much familiar with Low impedance Bus bar differential protection.
In case of high impedance bus bar differential protection scheme, Discriminating zone protection as well as Check Zone protection relays are provided and in addition CT pilot supervision also is a must.
What is the practice in case of low impedance numerical bus bar differential protection (with regard to 132kV outdoor switchyard with Breaker-and-Half scheme):
- Is it standard to have separate discriminating and check zones or can the numerical relay provide some other option
- How about CT pilot supervision

Appreciate any feedback and Thanks in anticipation.

 

[slavag]

Hi Raghun.
Of course is depend on the type of relay.
LI BBP is include minimum two criterions for trip, and lot of them with discriminating and check zones . Please remember, LI BBP is young brother of HI BBP with more or less same algorithms. LI BBP also include futures, like to O/C or U/V start for the BBP ( with internal or external option)

Im not sure, if I inderstood exactly, what is CT pilot supervision. Lot of LI BBP have futures like to : CT open circuit, fast and low, differntial current, all of them with blockimg and signalling option.

Of course LI BBP is iclude dynamic replica in all types of schemes ( single BB, double BB, one and half CB, coupler CB with two or one CT, etc). and more and more..

Best Regards.
Slava