25kV Bus Fault clearing time
25kV Bus Fault clearing time
(OP)
Hi,
Just curious (if anyone knows) what are typical clearing times for a 25kV bus fault from the protections?
zone1 and zone2?
Does adding an NGR change this? (Assuming Zone 2 will come upstream form the TX prot)
Does the choice of having a high impedance vs low impedance relay affect these?
EDIT: Sorry forgot to add, im in Canada, AB., also mainly (but not only) interested in Phase to ground or phase to phase to ground or 3-phase to ground.
Thanks.
Just curious (if anyone knows) what are typical clearing times for a 25kV bus fault from the protections?
zone1 and zone2?
Does adding an NGR change this? (Assuming Zone 2 will come upstream form the TX prot)
Does the choice of having a high impedance vs low impedance relay affect these?
EDIT: Sorry forgot to add, im in Canada, AB., also mainly (but not only) interested in Phase to ground or phase to phase to ground or 3-phase to ground.
Thanks.






RE: 25kV Bus Fault clearing time
RE: 25kV Bus Fault clearing time
NGR won't have any impact.
Decent differential protection with a decent breaker will give you sub-5 cycle clearing time.
Whether or not to use a high-impedance differential set up depends if fault levels are high enough such that a close in (but out-of-zone) fault doesn't saturate the Bus CTs, which would cause an over-trip of the Bus.