Open Delta

[speedtronic]

Can someone please explain how an open delta VT principle is used to detect earth fault in some cable or winding?

 

[AEC]

Are you talking about Neutral Voltage Displacement?

 

[ghost]

Voltage transformers (VTs) for a three-phase power line can be wired into different primary/secondary configurations. The input (primary) side of the voltage transformers receives the three phases of the power line voltage signal, while the output (secondary) side produces reduced voltage values which are then applied to a protective relay or more particularly another set of voltage transformers in a protective relay, which reduce the voltage values from the power system VTs to levels which can be used by the processing circuitry in the protective relay.