ABB RELION RET670 Applications Manual page 177

1MRK 504 163-UUS A
3·87
ANSI05000176 V2 EN-US
Figure 59: Application of the1Ph High impedance differential protection HZPDIF (87) function on a reactor
Transformer protection RET670 2.2 ANSI
Application manual
Setting example
It is strongly recommended to use the highest tap of the CT whenever
high impedance protection is used. This helps in utilizing maximum CT
capability, minimize the secondary fault, thereby reducing the stability
voltage limit. Another factor is that during internal faults, the voltage
developed across the selected tap is limited by the non-linear resistor
Section 7
Differential protection
ANSI05000176-2-en.vsd
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