ABB Relion REC670 Applications Manual page 101

1MRK 511 358-UEN A
3·Id
IEC05000165 V2 EN-US
3·Id
IEC05000739 V2 EN-US
Figure 36: The protection scheme utilizing the high impedance function for the T-feeder
Normally this scheme is set to achieve a sensitivity of around 20 percent of the used CT
primary rating so that a low ohmic value can be used for the series resistor.
Application manual
Section 6
Differential protection
IEC05000165-2-en.vsd
IEC05000739-2-en.vsd
95