Voltage measurement on insulated earth systems

[Hunterino]

Hi

On a marine vessel there is no neutral and no connection to earth from the generator. Typical 440V and 600V generator systems.

If there is no earth faults will i measure approx half the line voltage to earth?

If there is an earth fault on one phase should i expect a lower if not zero voltage to earth on that phase?

 

[Skogsgurra]

You will probably measure voltage/sqrt(3) when you measure from line to ground. But the actual voltage changes a lot depending on leakage currents and if there are more cables connected to one phase, increses capacitance to ground so that the whole system shifts.

Yes. A ground fault on one phase will make that phase exhibit zero volt to ground. That is fairly obvious, don't you think?

Gunnar Englund

http://www.gke.org

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