L-G fault in 3-ph system
L-G fault in 3-ph system
(OP)
In a 3-ph system with neutral not solidly grounded, why the phase voltage of unfaulted lines gets increased 1.732 times its nominal voltage in the event of a L-G fault.
Mathematically, it is clear but what actually is happening in reality?
Mathematically, it is clear but what actually is happening in reality?






RE: L-G fault in 3-ph system
RE: L-G fault in 3-ph system
RE: L-G fault in 3-ph system
RE: L-G fault in 3-ph system
You can look at:
http://www.i-gard.com/appguides.htm
lots of good info, in the beginning of the application guide named "ground fault protection on ungrounded and HRG system", they explain that
RE: L-G fault in 3-ph system
Regards
Marmite
RE: L-G fault in 3-ph system
The phase voltage DOES NOT get increased.
The voltage to ground from the two unfaulted phases increases.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: L-G fault in 3-ph system
RE: L-G fault in 3-ph system
In fact with certain earth fault resistance one of the two healthy phase-to-earth voltages will rise up to sqrt(3) + 5.2 % => 1.82 Un.
This maximum happens, when the fault resistance is about 37 % of the total ground reactance Xcap of the network.
RE: L-G fault in 3-ph system
"In fact with certain earth fault resistance one of the two healthy phase-to-earth voltages will rise up to sqrt(3) + 5.2 % => 1.82 Un.
This maximum happens, when the fault resistance is about 37 % of the total ground reactance Xcap of the network".
It's really new for me. Ransor, I assume is same for Petersen coil system. Tanks a lot for information, it's probably explained me several cases.
Best Regards.
Slava