Breaker failure protection 2

[ldcktm]

Hi everybody
good morning
I have a small question. In breaker failure protection, whether we have to use a separate secondary core of the CT or we can use the same core as used to other protection system eg over current protection ? What is the general practice. Could anybody let me know
regards
Rajendra

 

[slavag]

Hi.
It's depend on your application ( votage level) and rules in your/customer companies.

Up to 35kV in lot of companies use BFP built in in the relays.
For subtransmission and transmission level usually used separated core for BFP it's part from BBP.

In few companies BFP is part of CB control relay and that means, separate core.

For my pinion, preferd separate core.

Hope it help.
Best Regards.
Slava

 

[ldcktm]

This is intended for 132 kV transmission line of length 6 km .

 

[slavag]

Hi.
If you have some problem with additional core, you can use same core as protection or used built in BFP into protection relay.
It's also OK, don't worry.
Best Regards.
Slava

 

[ldcktm]

hi
Thanks a lot for your kind response
regards
Rajendra

 

[davidbeach]

Most modern relays are capable of doing their own breaker failure protection, no need for separate relays or separate CTs.

 

[cranky108]

Many breaker failure schemes require an input from a protective relay to start the breaker failure timer. So to have an input from a protective relay, it must be seeing current from a good CT. So that good CT can be used.