ABB RELION REX640 Technical Manual page 550

Section 4
Protection functions
544
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Figure 296: Operation in "Alarming EF" mode
Intermittent EF
Operation mode "Intermittent EF" is used to detect restriking or intermittent earth
faults. A required number of intermittent earth fault transients set with the Peak
counter limit setting must be detected for operation. Therefore, transient faults or
permanent faults with only initial fault ignition transient are not detected in this mode.
The application of "Intermittent EF" mode is limited to low ohmic intermittent or
restriking earth faults.
In the "Intermittent EF" mode, the operate timer is started when the following
conditions are met.
1MRS759142 C
REX640
Technical Manual