Uses of Current Transformer CT

The ranges of an AC ammeter can be extended by using current transformer CT. To measure high currents, CT’s are used in conjunction with measuring instruments. They find wide spread applications in protection circuits of power system for operation of relays.

Advantages of CT’s in extending the range are


  1. Metering circuit is isolated from high voltage power circuits.
  2. Low power consumption.
Ratio Error formula

Phase Angle Error

The angle by which the secondary current phasor, when reversed, differ in phase from the primary current phasor is called phase angle error.

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