HOW DISTANCE PROTECTION IS DONE IN EHV TRANSMISSION LINES?
WHAT IS THE BASIC TECHNIQ OR FUNDA USED BEHIND THIS ?
SPECIALLY EXPLAIN?IMPEDANCE METHOD.
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Answer Posted / krishna rao vutukuru
distance protection can be done in 3 ways by measuring
1)impedance method(impedance relay)
2)reactance method(reactance relay)
3)admittance method(mho relay)
reactance relay used for detection of earth faults(since it is indepedant of ground resistance)
mho relay is used for protection of long transmisson lines(since it is less affected by power swings)
impedance relay is used for protection of medium lenghth transmisson lines.
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