ABB Relion Technical Manual page 9

Technical manual
Elimination of zero sequence currents......................................... 98
Restrained and unrestrained limits of the differential protection...99
Fundamental frequency negative sequence differential currents101
Internal/external fault discriminator.............................................103
Unrestrained, and sensitive negative sequence protections...... 107
Instantaneous differential currents............................................. 109
Harmonic and waveform block criteria....................................... 109
Switch onto fault feature............................................................. 110
Logic diagram............................................................................. 111
Technical data................................................................................. 117
Restricted earth-fault protection, low impedance REFPDIF (87N)....... 118
Identification.................................................................................... 118
Functionality.................................................................................... 118
Function block................................................................................. 119
Signals.............................................................................................119
Settings............................................................................................120
Monitored data.................................................................................120
Operation principle.......................................................................... 121
Fundamental principles of the restricted ground fault protection121
Operate and restrain characteristic............................................ 124
Calculation of differential current and bias current..................... 125
Detection of external ground faults.............................................126
Algorithm of the restricted ground fault protection......................127
Technical data................................................................................. 128
1Ph High impedance differential protection HZPDIF (87).....................129
Identification.................................................................................... 129
Introduction......................................................................................129
Function block................................................................................. 129
Signals.............................................................................................129
Settings............................................................................................130
Monitored data.................................................................................130
Operation principle.......................................................................... 130
Logic diagram............................................................................. 130
Technical data................................................................................. 131
Generator differential protection GENPDIF (87G)................................ 131
Identification.................................................................................... 132
Functionality.................................................................................... 132
Function block................................................................................. 133
Signals.............................................................................................133
Settings............................................................................................134
Table of contents
3