Voltage transformer

Metering style PTs are designed with smaller cores and VA capacities than power transformers.

A small PT (see nameplate in photo) with a rating of 0.3W, 0.6X would indicate with up to W load (12.5 watts[1] ) of secondary burden the secondary current will be within a 0.3 percent error parallelogram on an accuracy diagram incorporating both phase angle and ratio errors.

The secondary is usually grounded on one terminal to avoid capacitive induction from damaging low-voltage equipment and for human safety.

There are three primary types of potential transformers (PT): electromagnetic, capacitor, and optical.

The tuning of the divider to the line frequency makes the overall division ratio less sensitive to changes in the burden of the connected metering or protection devices.