Question

in impedance relay, current element torque should be greater than voltage element torque.

Answer 1

hey mate your answers is


There is one type of relay which functions depending upon the distance of fault in the line. More specifically, the relay operates depending upon the impedance between the point of fault and the point where relay is installed. These relays are known as distance relay or impedance relay.

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Answer 2

Impedance Relay

There is one type of relay which functions depending upon the distance of fault in the line. More specifically, the relay operates depending upon the impedance between the point of fault and the point where relay is installed. These relays are known as distance relayor impedance relay.

Working Principle of Distance or Impedance Relay

The working principle of distance relay or impedance relay is very simple. There is one voltageelement from potential transformerand an electric current element fed from current transformer of the system. The deflecting torque is produced by secondary electric current of CT and restoring torque is produced by voltage of potential transformer. In normal operating condition, restoring torque is more than deflecting torque. Hence relay will not operate. But in faulty condition, the electric currentbecomes quite large whereas voltage becomes less. Consequently, deflecting torque becomes more than restoring torque and dynamic parts of the relay starts moving which ultimately close the No contact of relay. Hence clearly operation or working principle of distance relay, depends upon the ratio of system voltageand current. As the ratio of voltageto electric current is nothing but impedance a distance relay is also known as impedance relay.