ABB RELION REX640 Technical Manual page 571

1MRS759142 F
Figure 328: Operation in "General EF" mode
Alarming EF
Operation mode "Alarming EF" is applicable in all kinds of earth faults in
high-impedance earthed networks, that is, in compensated, unearthed and high
resistance earthed networks, where fault detection is only alarming. It is intended
to detect earth faults regardless of their type (transient, intermittent or restriking,
permanent, high or low ohmic).
In "Alarming EF" mode, the operate timer is started during the following conditions.
• Earth fault is detected by the GFC
• Fault direction equals
•
Estimated stabilized fundamental frequency residual current
set
supervision, and which is further defined with setting
(available options are "Adaptive", "Amplitude" and "Resistive").
REX640
Technical Manual
Directional mode setting
Min operate current level, which is applied in current magnitude threshold
Protection functions
1
I
exceeds the
o stab
Operating quantity
571