Ground Fault Current Split - two online gens with one grounded
Ground Fault Current Split - two online gens with one grounded
(OP)
Assume two 4160 V generators online on an islanded system; one is grounded through a transformer/resistor, the other ungrounded (as recommended by various sources including Eng-tips).
My question relates to a fault on the ungrounded gen. It is a straight-forward exercise to show the path the fault current flows when the fault is on the grounded gen, but what about the ungrounded gen? If a fault occurs say 50% down one winding, what "circular" route will the current flow? This is probably best illustrated with a drawing, but I am not sure this forum will allow that...
TIA
Ken Almon
My question relates to a fault on the ungrounded gen. It is a straight-forward exercise to show the path the fault current flows when the fault is on the grounded gen, but what about the ungrounded gen? If a fault occurs say 50% down one winding, what "circular" route will the current flow? This is probably best illustrated with a drawing, but I am not sure this forum will allow that...
TIA
Ken Almon






RE: Ground Fault Current Split - two online gens with one grounded
RE: Ground Fault Current Split - two online gens with one grounded
Discussing differential protection, C37.96-88 §2.4.7 states: “These [87] relays detect low-magnitude fault currents during normal loads and do not trip falsely during high-magnitude external faults. Differential relays cannot detect turn-to-turn faults in the same winding.”
For the least amount of long-term trouble, it’s worrh seeong that the type, ratio, and kneepoint of CTs should to be identical—called out and proven in commissioning.
RE: Ground Fault Current Split - two online gens with one grounded
Thank you for your timely response.