ABB RELION REX640 Technical Manual page 569

Protection and control

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1MRS759142 F

Figure 327: 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".

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

Estimated stabilized fundamental frequency residual current

supervision, and which is further defined with setting

(available options are "Adaptive", "Amplitude" and "Resistive").

Technical Manual

Reset delay time

Min operate current level which is applied in current magnitude threshold

Directional mode setting

Protection functions

Reset delay time

Operating quantity