Where there is a chance of CT ratio mismatch and / or polarity change and / or CT used mixing with new and old and / or CT s are different make type etc, it is better to use low impedance differential protection. Moreover, low impedance protection work on current value but high impedance work on voltage across the relay terminal. Low impedance system: each CT wire needs to be connected to the relay but high impedance it is not so. Future feeder expansion may be difficult while the protection is low impedance type
Sir plz make video on significant of ct p1, p2, s1, s2 connection in protection system
Sir why then we use low impedance differential protection
Where there is a chance of CT ratio mismatch and / or polarity change and / or CT used mixing with new and old and / or CT s are different make type etc, it is better to use low impedance differential protection.
Moreover, low impedance protection work on current value but high impedance work on voltage across the relay terminal.
Low impedance system: each CT wire needs to be connected to the relay but high impedance it is not so.
Future feeder expansion may be difficult while the protection is low impedance type