Voltage Transformer

A voltage transformer, also called a potential transformer and abbreviated VT or PT, is a parallel-connected type of instrument transformer designed to present a negligible load to the circuit whose voltage it is measuring while maintaining an accurate voltage ratio and phase relationship between its primary and secondary windings. Like the current transformer with which it shares the instrument transformer classification, its purpose is to scale a power system actual, often dangerously high, voltage down to a small standardized value that metering equipment and protective relays connected to its secondary can measure and act on accurately and safely.