111R
Electrical
- May 4, 2012
- 114
I have a few questions on breaker failure schemes since there seems to be no consistency among the approaches I've come across.
Example: Radial Line Load Protected by (1) Distance Relay and (1) Overcurrent Relay - Fed from Ring Bus. Breaker 1 & 2 feed the radial line. Breaker 3 & 4 are adjacent to breaker 1 & 2, respectively.
If a fault occurs on the radial line, both the Distance Relay and Overcurrent Relay should attempt to open the two ring breakers to clear the fault. Should both of these relays simultaneously send a BFI to the relays controlling breaker 3 and the relays controlling breaker 4? Therefore, the relays for breaker 3 & 4 would start the BF timer and open if current is still flowing towards radial line terminal at expiration of timer?
I have seen some schemes where the relays at the radial line terminal will send a BFI to one of the adjacent terminal relays and start an internal BF timer in either the distance or overcurrent relay for the other terminal. The radial line terminal relay will then issue a BF Trip to other terminal after the timer expires. This continues in a clockwise or counterclockwise rotation around the ring bus.
If you have any links to technical papers on the approaches commonly used, that will be helpful
Thank you.
Example: Radial Line Load Protected by (1) Distance Relay and (1) Overcurrent Relay - Fed from Ring Bus. Breaker 1 & 2 feed the radial line. Breaker 3 & 4 are adjacent to breaker 1 & 2, respectively.
If a fault occurs on the radial line, both the Distance Relay and Overcurrent Relay should attempt to open the two ring breakers to clear the fault. Should both of these relays simultaneously send a BFI to the relays controlling breaker 3 and the relays controlling breaker 4? Therefore, the relays for breaker 3 & 4 would start the BF timer and open if current is still flowing towards radial line terminal at expiration of timer?
I have seen some schemes where the relays at the radial line terminal will send a BFI to one of the adjacent terminal relays and start an internal BF timer in either the distance or overcurrent relay for the other terminal. The radial line terminal relay will then issue a BF Trip to other terminal after the timer expires. This continues in a clockwise or counterclockwise rotation around the ring bus.
If you have any links to technical papers on the approaches commonly used, that will be helpful
Thank you.