ABB RELION RET670 Applications Manual page 9

Transformer protection RET670 2.2 ANSI
Application manual
Operation principle.......................................................................... 116
Frequency reporting................................................................... 118
Reporting filters.......................................................................... 120
Scaling Factors for ANALOGREPORT channels....................... 121
PMU Report Function Blocks Connection Rules in PCM600
Application Configuration Tool (ACT)......................................... 123
Setting guidelines............................................................................ 129
Section 7 Differential protection........................................................ 135
Transformer differential protection T2WPDIF and T3WPDIF (87T)......135
Identification.................................................................................... 135
Application....................................................................................... 135
Setting guidelines............................................................................ 136
Restrained and unrestrained differential protection....................136
Elimination of zero sequence currents....................................... 140
Inrush restraint methods.............................................................140
Overexcitation restraint method..................................................140
Cross-blocking between phases.................................................141
External/Internal fault discriminator............................................ 141
On-line compensation for on-load tap-changer position.............143
Differential current alarm............................................................ 144
Open CT detection..................................................................... 144
Switch onto fault feature............................................................. 145
Setting example...............................................................................145
Introduction.................................................................................145
Typical main CT connections for transformer differential
protection....................................................................................146
Application Examples................................................................. 147
Summary and conclusions......................................................... 155
High impedance differential protection, single phase HZPDIF (87)......157
Identification.................................................................................... 157
Application....................................................................................... 158
The basics of the high impedance principle............................... 158
Connection examples for high impedance differential protection.... 164
Connections for three-phase high impedance differential
protection....................................................................................164
Connections for 1Ph High impedance differential protection
HZPDIF (87)............................................................................... 165
Setting guidelines............................................................................ 166
Configuration.............................................................................. 167
Settings of protection function.................................................... 167
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