ABB REF615 Applications Manual page 45

1MRS756378 D
REF615
Application Manual
A071318 V4 EN
Figure 10: Directional earth-fault protection
Three stages are offered for directional earth-fault protection. In addition, there is a
dedicated protection stage (INTRPTEF) either for transient based earth-fault
protection or for cable intermittent earth-fault protection in compensated networks.
A dedicated non-directional earth-fault protection block (EFHPTOC) is intended for
protection against double earth-fault situations in isolated or compensated networks.
This protection function uses the calculated residual current originating from the
phase currents.
All operate signals are connected to the Master Trip and also to the alarm LEDs. LED
2 is used for directional earth-fault and LED 3 for double earth-fault protection operate
indication.
Section 3
REF615 variants
39