Phase-Earth voltage in an ungrounded system during fault

[ekuegler]

Can anyone confirm what readings I should be obtaining when testing for voltage phase-earth on a system which is ungrounded and has a ground fault. 440v phase-phase in normal operation. Would a voltage of 440v to earth indicate a ground fault or would you expect zero volts in the grounded phase and upto 173% in the others phase to earth.

If anyone can confirm please

 

[magoo2]

It's easier to visualize if you use a delta system as your example. If you ground one of the phases, the voltage at that point is 0 volts. The other two phases maintain the phase to phase voltages, which in this case are the phase to ground voltages.