Functions

• Differential protection

– Transformer differential protection, two winding (PDIF, 87T)

– Transformer differential protection, three winding (PDIF, 87T)

– Restricted earth fault protection (PDIF, 87N)

– High impedance differential protection (PDIF, 87X)

• Distance protection

– Distance protection zones (PDIS, 21)

– Phase selection with load encroachment (PDIS, 21)

– Power swing detection (RPSB, 78)

– Automatic switch onto fault logic (PSOF)

• 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, two time constants (PTTR, 49)

– Breaker failure protection (RBRF, 50BF)

– 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)

– Overexcitation protection (PVPH, 24)

• Frequency protection

– Underfrequency protection (PTUF, 81)

– Overfrequency protection (PTOF, 81)

– Rate-of-change frequency protection (PFRC, 81)

• Multipurpose protection

– General current and voltage protection (GAPC)

• Secondary system supervision

– Current circuit supervision (RDIF)

– Fuse failure supervision (RFUF)