Hi

Is there a way to detect a ground fault on a Delta system without the use of an ZIGZAG transformer?

 

> Is there a way to detect a ground fault on a Delta system
> without the use of an ZIGZAG transformer?

Good discussion here: http://electronics.stackexchange.com/questions/107059/3-phase-voltage-ok-indicating-lights

 

Assuming an ungrounded delta system, three voltmeters each connected and measuring one line to ground. Old detectors simply used three lamps.

Inductive and capacitive coupling will keep voltage at approximately line-to-line divided by square root of 3. A single bolted ground fault will cause the respective voltmeter reading to approach zero and the other two to approach line voltage.

 

In the US this is actually required by the electrical code. If you have an ungrounded system, it's required to have ground detectors. Usually these are lights connected from each phase to ground. Normally all three lights are dim. If one of the phases becomes grounded, the light associated with that face all shut off and the other two phase lights will go bright.

 

One way might be to use a wye-grounded // broken-delta set of PTs. That should give a measurement of 3V_0.

>Is there a way to detect a ground fault on a Delta system
>without the use of an ZIGZAG transformer?