6.2.3 Function block.................................................................................................................................. 145
6.2.4 Signals................................................................................................................................................ 145
6.2.5 Settings.............................................................................................................................................. 145
6.2.6 Monitored data.................................................................................................................................146
6.2.7 Operation principle..........................................................................................................................146
6.2.7.1 Logic diagram................................................................................................................................147
6.2.8 Technical data...................................................................................................................................148
6.3 Generator differential protection GENPDIF (87G).........................................................................148
6.3.1 Identification.....................................................................................................................................149
6.3.2 Functionality..................................................................................................................................... 149
6.3.3 Function block.................................................................................................................................. 150
6.3.4 Signals................................................................................................................................................ 150
6.3.5 Settings.............................................................................................................................................. 151
6.3.6 Monitored data................................................................................................................................. 153
6.3.7 Operation principle.......................................................................................................................... 153
6.3.7.1 Function calculation principles.................................................................................................. 154
6.3.7.2 Fundamental frequency differential currents.........................................................................154
6.3.7.3 Supplementary criteria................................................................................................................ 158
6.3.7.4 Harmonic restrain.........................................................................................................................160
6.3.7.5 Open CT detection feature..........................................................................................................161
6.3.7.6 Cross-block logic scheme............................................................................................................162
6.3.8 Technical data...................................................................................................................................165
6.4 Low impedance restricted earth fault protection REFPDIF (87N)..............................................166
6.4.1 Identification.....................................................................................................................................166
6.4.2 Functionality..................................................................................................................................... 166
6.4.3 Function block...................................................................................................................................167
6.4.4 Signals................................................................................................................................................ 167
6.4.5 Settings..............................................................................................................................................168
6.4.6 Monitored data.................................................................................................................................169
6.4.7 Operation principle..........................................................................................................................169
6.4.7.1 Fundamental principles of the restricted ground fault protection....................................169
6.4.7.2 Restricted ground fault protection, low impedance differential protection.................... 171
6.4.7.3 Calculation of differential current and bias current...............................................................172
6.4.7.4 Detection of external ground faults.......................................................................................... 173
6.4.7.5 Algorithm of the restricted ground fault protection.............................................................174
6.4.8 Technical data................................................................................................................................... 175
Section 7 Impedance protection......................................................................................... 177
7.1 Distance measuring zones, quadrilateral characteristic ZMQPDIS (21), ZMQAPDIS (21),
ZDRDIR (21D).......................................................................................................................................... 177
7.1.1 Identification..................................................................................................................................... 177
7.1.2 Functionality......................................................................................................................................177
7.1.3 Function block...................................................................................................................................178
Table of contents
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Technical manual
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