Transformer Mechanical Protection BF Initiation
The Breaker failure protection is used for protect the breaker when fail to open for a Protection trip.
If any protection Lock out operate it will give a trip to CB and initiate the BF relay.
After minimum time BF relay will check the CB status and fault current flow then relay will give one more trip to the CB. Now CB is still fail to open then BF relays initiate BF second stage lock out and give trip to adjacent CBs and save faulty CB.
But transformer Mechanical protection ( Main tank Bucholz relay Operate and winding temperature high and oil temperature high, PRD ) Operation independent of fault current.
Therefore BF relay should not consider fault current for transformer Mechanical protection initiation.
This initiation separate given as digital input in Numerical relays REB 500 (ABB),7VK61 ( Siemens)
But this initiation will initiate the first and second stage timers in normal non numerical relays ( RAICA - ABB).
The Breaker failure protection is used for protect the breaker when fail to open for a Protection trip.
If any protection Lock out operate it will give a trip to CB and initiate the BF relay.
After minimum time BF relay will check the CB status and fault current flow then relay will give one more trip to the CB. Now CB is still fail to open then BF relays initiate BF second stage lock out and give trip to adjacent CBs and save faulty CB.
But transformer Mechanical protection ( Main tank Bucholz relay Operate and winding temperature high and oil temperature high, PRD ) Operation independent of fault current.
Therefore BF relay should not consider fault current for transformer Mechanical protection initiation.
This initiation separate given as digital input in Numerical relays REB 500 (ABB),7VK61 ( Siemens)
But this initiation will initiate the first and second stage timers in normal non numerical relays ( RAICA - ABB).
