ABB RELION REX640 Technical Manual page 552

Section 4
Protection functions
546
GUID-C3B6910E-1114-4396-A891-5DDB9490333A V1 EN
Figure 297: Operation in "Intermittent EF" mode, Peak counter limit = 3
Transient EF
Operation mode "Transient EF" is dedicated for detecting fast transient faults where
the fault current stays on only for a very short time. It is recommended method in
networks, where network damping has very small value or when parallel resistor of
the coil is not used, for example in sub-transmission networks.
In the "Transient EF" mode, the fault direction is determined from the beginning of the
fault and is held until earth-fault is detected by GFC.
In the "Transient EF" mode, the operate timer is started when the following conditions
are met.
1MRS759142 C
REX640
Technical Manual