Best Option for Overcurrent Protected Taps on Distance Protected Line
Best Option for Overcurrent Protected Taps on Distance Protected Line
(OP)
On a line protected by instantaneous distance protection along the majority of the line, what is the best option for coordination with overcurrent protection on multiple taps with breakers feeding transformers at the end of a short line with negligible impedance?
For high side transformer faults on the taps, the distance protection will see these faults because the impedance is less than that of 80-90% of the main line, but it's not desirable to trip the entire line for a fault that can be interrupted by the breaker on the tap.
Is the best option to put instantaneous overcurrent protection on the taps and then delay the distance protection with a set delay of 6-10 cycles to allow clearing of the tap without tripping the entire line?
Thanks
For high side transformer faults on the taps, the distance protection will see these faults because the impedance is less than that of 80-90% of the main line, but it's not desirable to trip the entire line for a fault that can be interrupted by the breaker on the tap.
Is the best option to put instantaneous overcurrent protection on the taps and then delay the distance protection with a set delay of 6-10 cycles to allow clearing of the tap without tripping the entire line?
Thanks






RE: Best Option for Overcurrent Protected Taps on Distance Protected Line
RE: Best Option for Overcurrent Protected Taps on Distance Protected Line
RE: Best Option for Overcurrent Protected Taps on Distance Protected Line
RE: Best Option for Overcurrent Protected Taps on Distance Protected Line
Since the impedance down this radial line is less than the impedance to 80% of the long main line, it will be seen by the distance relay as being a Zone 1 fault. So, there will be a race condition between the distance relay zone 1 and the instantaneous overcurrent on the tap unless the distance relay is delayed to allow the overcurrent to trip first.
RE: Best Option for Overcurrent Protected Taps on Distance Protected Line
RE: Best Option for Overcurrent Protected Taps on Distance Protected Line