What is the function of earth fault relay?

Earth Fault Relay (EFR) It is a safety device used in electrical installations with high earth impedance. It detects small stray voltages on the metal enclosures of electrical equipment. The result is to interrupt the circuit if a dangerous voltage is detected.

What is the effect of arc resistance on distance relay?

 The arc resistance causes the distance relay to under-reach.  Due to presence of arc resistance, the impedance seen by the relay appears to be more than the actual value of the impedance up to the fault point and the relay tends to underreach.

What is the difference between earth fault and earth leakage?

Earth fault current: Current flowing to earth due to an insulation fault. Earth leakage current: Current flowing from the live parts of the installation to earth in the absence of an insulation fault.

What causes Earth leakage?

Causes of Earth Leakage Earth leakage may occur in underground transmission lines due to insulation damage of cables. So when earth leakage occurs due to insulation failure of the live conductor, leakage current flows from the transformer or motor body to ground through the grounding conductor.

Which relay gets most affected by arc resistance?

the Mho relay
The operation of the Mho relay is most affected due to arc resistance.

Which relay is not affected by arc resistance?

reactance relay
For very short line sections, the reactance type is preferred for the reason that more of the line can be protected at high speed. This is because the reactance relay is practically unaffected by arc resistance which may be large compared with the line impedance, as described elsewhere in this chapter.

What is the basic difference between overload relay and earth relay?

Over load relays are used in control and power circuits to protect the motor from over load /over current. Earth fault relay that means phase to ground fault will occur the relay gets activated but phase relay means phase to phase fault, open circuit fault and short circuit fault occuring that relay gets activated.