# RF Wireless World

## current transformer vs voltage transformer-Difference between current transformer and voltage transformer

This page on current transformer vs voltage transformer describes basic difference between current transformer and voltage(potential) transformer types.

As we know instrument transformers are used in A.C. systems for the measurement of current, voltage(potential), power and energy. They are also used in protection circuits meant to operate relays of various types.

Transformation ratio is the ratio of magnitude of primary phasor to the secondary phasor.

### Current Transformer-C.T.

• Primary winding of a current transformer is connected in series with load. It carries load current to be measured.

The primary winding has very few turns while secondary winding has more turns. • The instrument is directly connected across the secondary winding.

Transformation Ratio for C.T. = (Primary Winding Current)/(Secondary winding current)

Turns Ratio for C.T. = (Number of turns of secondary winding)/(Number of turns of primary winding)

### Voltage Transformer | Potential Transformer

• These are used for measurement of high voltages using low range voltmeters.

• Primary winding of voltage transformer is connected across line whose voltage is to be measured. The voltage circuit is connected across the secondary winding.

Transformation Ratio for voltage transformer = (Primary Winding voltage)/(Secondary winding voltage)

Turns Ratio for P.T. = (Number of turns of primary winding)/(Number of turns of secondary winding)