The differential current relays type SKC is intended for the protection of generators, large motors, two winding power transformers and short lines. The following functions are provided:

thermal (49) for transformer programmable on one of the two sides;
overload (51) and short circuit (50) independently programmable on both sides;
earth fault (50N-51N) or restricted earth fault (87N);
biased differential function for transformers with second and fifth harmonic restraint (87T);
biased differential function for motors, generators, and short lines (87G).