ABB Relion Technical Manual page 10

Table of contents
4
Operation principle.......................................................................... 135
Function calculation principles....................................................137
Fundamental frequency differential currents.............................. 137
Supplementary criteria................................................................142
Harmonic restrain....................................................................... 145
Cross-block logic scheme...........................................................145
Simplified block diagrams...........................................................146
Technical data................................................................................. 148
Section 7 Impedance protection........................................................151
Power swing detection ZMRPSB (68).................................................. 151
Identification.................................................................................... 151
Functionality.................................................................................... 151
Function block................................................................................. 151
Signals.............................................................................................152
Settings............................................................................................152
Operation principle.......................................................................... 153
Resistive reach in forward direction............................................155
Resistive reach in reverse direction............................................155
Reactive reach in forward and reverse direction........................ 156
Basic detection logic...................................................................156
Operating and inhibit conditions................................................. 158
Technical data................................................................................. 159
Underimpedance protection for generators and transformers
ZGCPDIS (21G)....................................................................................159
Identification.................................................................................... 159
Functionality.................................................................................... 159
Function block................................................................................. 160
Signals.............................................................................................161
Settings............................................................................................161
Operation principle.......................................................................... 162
Full scheme measurement......................................................... 162
Impedance characteristic............................................................162
Basic operation characteristics...................................................163
Theory of operation.................................................................... 165
Technical data................................................................................. 166
Loss of excitation LEXPDIS (40).......................................................... 167
Identification.................................................................................... 167
Functionality.................................................................................... 167
Function block................................................................................. 167
Technical manual