ABB RELION REX640 Technical Manual page 542

Section 4
Protection functions
536
+90 deg.

Tilt angle
-90 deg.
GUID-D8B2E0B2-07FB-467F-A49C-98189BAF3456 V1 EN
Figure 291: Operating quantity = "Resistive" and Directional mode = "Forward"
The resistive mode is valid for resonant earthed networks and high-resistance earthed
systems, but not in case of unearthed networks. The resistive mode must be selected
when there is a risk of local overcompensation of a protected feeder, that is, when the
earth-fault current is compensated with distributed compensation coils and their
inductive current exceeds the amount of capacitive current produced by the phase-to-
earth capacitances of the feeder.
In compensated networks, where distributed compensation coils are
also used to compensate earth-fault current, setting Operating
quantity should be set to "Resistive". This enables secure and
dependable directional determination also in case of local
overcompensation where the earth-fault current produced by the
healthy feeder can become inductive.
When Operating quantity is set to "Amplitude", the set minimum operate current
threshold (setting Min operate current) is compared to the amplitude of
whole defined operate sector (see
networks.
+45 deg.

0 deg.


Figure 292). This selection can be used in unearthed
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REX640
Technical Manual