Fault Current
Fault Current
(OP)
Gents
can you help me figure out how the fault current at 11kv pole substation (first feeder out) say,2km out, returns to its source (Zone Substation)? Soil resistivity is less than 100 ohm m. Earthing at the pole sub is 2 x 2.4m electrode for HV & LV. Assuming a L-G fault happens at 11kV side.
regards,
Danilo
can you help me figure out how the fault current at 11kv pole substation (first feeder out) say,2km out, returns to its source (Zone Substation)? Soil resistivity is less than 100 ohm m. Earthing at the pole sub is 2 x 2.4m electrode for HV & LV. Assuming a L-G fault happens at 11kV side.
regards,
Danilo






RE: Fault Current
RE: Fault Current
Thanks DPC...thats correct but no LV neutral is installed
between first pole sub and the source(zone sub)
RE: Fault Current
RE: Fault Current
need yo know the SCA and equivalent reactance at the main bus and the feeder reactance.
Primary fault current return via neutral and ground resistance to source former which may be 2 if it has a close breaker?
RE: Fault Current
RE: Fault Current
RE: Fault Current
The pole top sub fuses is to isolate the faulted transformer for internal ground faults near the terminals and for terminal faults if they are single phase xformers and offer limited overload protection.
Do you have series reactors at the feeder sub ahead of the feeder breaker ?
RE: Fault Current
RE: Fault Current
One thing is universal however - there must exist a complete circuit path. For a line-to-ground fault, the current must return to the transformer neutral - otherwise there is no current. But it can find a variety of paths to get from the fault point back to the transformer - any grounded conductor will do.
RE: Fault Current
RE: Fault Current
RE: Fault Current
RE: Fault Current
Anyway,i'll try to use terms where you are familiar so it wont confuse you. the question is , how is the L-G fault current occured at the HV side of 11kV/430v Delta Wye Distribution Transformer goes back to 132kv/11kv Substation (source)? The 11kV U/G first feeder out (with cable screens) from that substation terminated approx 1km to a pothead,then goes to OH Dist Transformer approx 1km from the pothead. So,the total distance from 132/11kv Substation to OH Dist Xformer is approx 2km. There is no grounding transformer on the 11kV bus but the cable screen of 11kV feeder at substation end is bonded to main sub earth grid and grounded on the pothead side.
Also,if the fault occurs at the pothead,how is the L-G fault current goes back to 132/11kV Substation?
Regards
Danilo
RE: Fault Current
A ground fault at the pot head will return to the 132/11kV transformer through what ever path it finds. If it's a high impedance return path the fault current will be low.
RE: Fault Current
RE: Fault Current
thanks for your replies..well appreciated.
regards,
Danilo
RE: Fault Current
I think, on ungrounded systems, the fault current-phase-to-ground-returns to the source only through capacities of the other two healthy phases to ground.
RE: Fault Current
Bill
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RE: Fault Current
RE: Fault Current
RE: Fault Current