Where is distance protection applied?

Where is distance protection used?

Distance relays are generally used for phase-fault primary and back-up protection on subtransmission lines, and on transmission lines where high-speed automatic reclosing is not necessary to maintain stability and where the short time delay for end-zone faults can be tolerated.

What is distance protection of transmission lines?

Distance Protection is a Non-unit System of Protection, which measures the Impedance between the Relay Location and the point where the fault is incident and compares it with the Set Value. If the measured Impedance is less than the Set Value , the Relay operates and Isolates the Faulty Section.

Why distance protection is used?

Distance protection schemes are commonly employed for providing the primary or main protection and backup protection for AC transmission line and distribution line against three phase faults, phase-to-phase faults, and phase-to-ground faults.

What is distance relay and where it is used?

A distance relay is a type of protection relay most often used for transmission line protection. Distance relays measure the impedance from the installation side to the fault location and operates in response to changes in the ratio of measured current and voltage.

Which relay is used for distance protection?

The admittance relay is the most commonly used distance relay. It is the tripping relay in pilot schemes and as the backup relay in step distance schemes.

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Which of the relay used for distance protection can also be used for protection of alternator against field failure?

Under frequency relay: Under frequency relay is used to protect the alternator when the frequency drops below the operating frequency. It is a backup protection for over fluxing (V/F) protection. Under frequency occurs due to turbine low speed, grid frequency fluctuation, etc.