ABB RELION REX640 Technical Manual page 548

Section 4
Protection functions
542
GUID-8EFFEC9E-77CD-4534-8C3E-E10BB61575DA V1 EN
Figure 295: 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 Directional mode setting
•
Estimated stabilized fundamental frequency residual current
set Min operate current level, which is applied in current magnitude threshold
1MRS759142 C
1
I
exceeds the
o stab
REX640
Technical Manual