Stuck Protection 2

[newelecteng]

Hi all,

what is stuck protection and how is it relate to BBP, Diff, CBF.
Some engineers told me: stuck protection is like BBP but it just feed from Incomers CT and Bus section CT.

Thanks.

 

[RRaghunath]

Breaker fail protection (CBF protection) is some times called 'Stuck breaker' protection. This is wired to trip all the breakers connected to the subject busbar in case of transmission swithyards and in case of distribution busbars, to trip the incomer and bus section breakers.
Some utilities prefer to provide partial differential protection to distribution busbars using incomer and bus section CTs. This is an economical alternative to full-fledged busbar protection. Demerit is that this cannot be set sensitive and fast acting as it is monitoring the current inflow in to the subject busbar from incomer as well as bus section and is coordinated with the outgoing feeder protection.
This may not be a concern in case of CBF (stuck breaker) as the trip is directly wired to the trip coils of incomer and bus coupler breakers.

 

[crshears]

BBP?

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[newelecteng]

RRaghunath
I understand from you that Stuck Protection is like partial BusBar protection (BBP) just fed from INCOMERS CTs and Bus Section CT
due to economical reason. But in this case we will have differential current in all time.

 

[davidbeach]

No, stuck protection is just an odd term for breaker failure (stuck breaker) protection. Today it's done in the tripping relays, back when individual relays did less it was a separate relay. When a trip occurs the breaker failure protection is initiated, whether internal to the relay that did the tripping or externally to another relay, and if the breaker open conditions aren't satisfied within the breaker failure time, a breaker failure trip is issued. For simple bus a breaker failure trip trips the same lockout relay as the bus protection. It isn't the bus protection, and it shouldn't be confused with the bus protection but it seems to be at times.

 

[newelecteng]

Hi davidbeach
many people confirm stuck protection like partial BusBar protection (BBP) just fed from INCOMERS CTs and Bus Section CT

 

[Mbrooke]

For breaker fail you trip all the breakers attached to the buss with the stuck breaker connected.


For a buss fault you initiate breaker failure for each individual breaker required to trip for said bus fault. This way a stuck breaker will not result in re-energizing the faulted bus, you don't risk clearing remote ends, and clearing will be sped up. The BF should send a direct transfer trip to the remote end and trip + block reclose on any local breaker.

 

[RRaghunath]

Stuck beaker protection is same as CBF protection. This trips incomer and bus section breakers.
Partial differential protection sees current all the time, you are right.
The magnitude of current in partial differential protection is equal to the total load fed from the subject busbar and this fact is to be considered while deciding the pickup setting.
The trip relay of partial differential protection can be triggered by stuck breaker protection as well (since both protections intend to trip incomer and bus section breakers).