ABB RELION REX640 Technical Manual page 546

Section 4
Protection functions
540
VG
IG
PEAK_IND
GFC
release
Reset timer
INTR_EF
Reset delay time
GUID-58BCE12B-E8B6-469C-B39A-251AA6031EBF V1 EN
Figure 294: Example of operation of Transient detector: indication of detected
transient by PEAK_IND output and detection of restriking or
intermittent earth fault by INTR_EF output (setting Peak counter limit
= 3)
Operation logic
MFADPSDE supports four operation modes selected with setting Operation mode:
"General EF", "Alarming EF", "Intermittent EF" and "Transient EF".
General EF
Operation mode "General EF" is applicable to various earth faults in high-impedance
earthed networks, that is, in compensated, unearthed and high-resistance earthed
networks. It detects earth faults regardless of their type (transient, intermittent or
restriking, permanent, high or low ohmic) and provides definite operate time for
protection regardless of the fault type.
In "General EF" mode, the operate timer is started in 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
Reset delay time
1
I
exceeds the
o stab
REX640
Technical Manual