Functions 

• Differential protection

– High impedance differential protection (PDIF,87X)

• Current protection

– Instantaneous phase overcurrent protection(PIOC,50)

– Four step phase overcurrent protection(POCM,51/67)

– Instantaneous residual overcurrent protection(PIOC,50N)

– Four step residual overcurrent protection(PEFM,51N/67N)

– Thermal overload protection, one time constant (PTTR,26)

– Thermal overload protection, two time constants (PTTR,49)

– Breaker failure protection (RBRF,50BF)

– Stub protection (PTOC, 50STB)

– Pole discordance protection (RPLD,52PD)

• Voltage protection

– Two step undervoltage protection (PUVM,27)

– Two step overvoltage protection (POVM,59)

– Two step residual overvoltage protection(POVM,59N)