Strange fault event - 3 phase fault, Single phase fault or others
Strange fault event - 3 phase fault, Single phase fault or others
(OP)
All,
The following link contains a fault event graph. It shows that there was an event that ALL three phase currents were increasing for 4 ~ 5 cycles, however all three phase currents are in phase. During this event, C phase voltage is lower at 0.3 per unit. So, is it a single phase fault or three phase fault or others?
What if there are multiple ground points at CT secondary and there was a nearby single phase fault, will the relay (SEL-351) see something like this?
Thanks for your opinion.
Regards,
Bing
The following link contains a fault event graph. It shows that there was an event that ALL three phase currents were increasing for 4 ~ 5 cycles, however all three phase currents are in phase. During this event, C phase voltage is lower at 0.3 per unit. So, is it a single phase fault or three phase fault or others?
What if there are multiple ground points at CT secondary and there was a nearby single phase fault, will the relay (SEL-351) see something like this?
Thanks for your opinion.
Regards,
Bing






RE: Strange fault event - 3 phase fault, Single phase fault or others
RE: Strange fault event - 3 phase fault, Single phase fault or others
RE: Strange fault event - 3 phase fault, Single phase fault or others
RE: Strange fault event - 3 phase fault, Single phase fault or others
The transformer is Yg-Yg-D connection, and it is a wind farm. SEL-351 relay is at 115kV side and generation level is very low, about 1MVA. So, the Yg-Yg-D xmer is function as a grounding transformer for a fault at 115kV transmission line, so all three phases contains only zero sequence current.
Great! Thank you all for your help!