IN>: The setting of the residual current level (neutral current) which is used by the
evaluation logic to verify that a cross-country fault exists. The setting can typically
be 20% of base current (IBase) but the setting shall be above the maximum current
generated during a single earth-fault. A high sensitivity is not crucial as the two-
phase fault level normally is well above base current.
tIN: The time delay for detecting that the fault is cross-country. It should be set
longer than the expected duration of a transient residual current appearing for a
single earth-fault. Normal time setting is 0.1 - 0.15 s.
tUN: The time delay for a secure UN detecting that the fault is an earth-fault or
double earth-fault with residual voltage. Normal time setting is 0.1 - 0.15 s. It
should not be set shorter than tIN because that might bypass tIN prematurely.
tOffUN: The UN voltage has a reset drop-off to ensure correct function without
timing problems. Normal time setting is 0.1 s.
In the High speed distance protection ZMFPDIS, setting INReleasePE needs to be
set lower than the expected residual current during a cross-country fault. Otherwise
the distance protection might operate in the phase-to-phase loops which will bypass
the Phase preference logic.
Section 8 1MRK 506 369-UEN B
Impedance protection
454 Line distance protection REL670 2.2 IEC
Application manual
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