Transformer Relays with Breaker Faluire protection 2

[Mbrooke]

I know relays like the SEL487E provide integral breaker failure protection; but what other differential SEL relays do the same or can do the same? I am being told that while the economical SEL587 does not have a dedicated BF function, it can be imitated by programming a latch and timer while turning OUT103 into a BF initiate contact. Similar can be done with the SEL387A, and in this case I would not have to loose a dedicated differential lockout like with the 587.

 

[davidbeach]

I wouldn't consider the SEL-587 for utility work. Any of the rest of the SEL transformer real can do breaker failure protection; either natively or it can be built in the logic variables. You then need an output per breaker to trip the lockout on the other side of that breaker.

 

[Mbrooke]

Any idea what relays come with it standard and what require a logic build?

 

[davidbeach]

I know the 487E can do breaker failure for up to 5 breakers. I'm reasonably certain that the 787 can do two breakers worth of breaker failure. The 387 family would require you to use SV timers and overcurrent elements to do breaker failure protection.

 

[Mbrooke]

Any idea how to go about building BF timers in the logic? The next relays down are 387 and 387A, which fit the budget, but I am not finding anything overly helpful in the 387A manual.

 

[davidbeach]

SVn = (SV1 + TRIP) * (50Px +50Gx)
SVnPU = 10 (or what ever value you want for your BF timer.
OUTnnn = SVnT.

 

[Mbrooke]

Thanks!

And this can be set on each individual breaker?

 

[davidbeach]

Right, assuming that the CTs from each breaker are brought in separately. The 'x' would be the overcurrents associated with that breaker. You could have up to 4 depending on which flavor of 387.

 

[Mbrooke]

Correct, separate CT from each breaker. A BF initiate from an INxxx contact can also be easily configured?

 

[davidbeach]

SVn = (SV1 + TRIP + INnnn) * (50Px +50Gx)

 

[Mbrooke]

Thats what I was looking for, thanks