3I0Enable_PG
This setting opens up an opportunity to enable phase-to-ground measurement for
phase-to-phase-ground faults. It determines the level of residual current (3I0) above
which phase-to-ground measurement is activated (and phase-to-phase measurement is
blocked). The relations are defined by equation 303.
0 max
3I0Enable _ PG
3
100
ph
I
I I× ³ ×
EQUATION2548-ANSI V1 EN-US (Equation 303)
Where:
3I0Enable_PG
the setting for the minimum residual current needed to enable operation in the phase-
to-ground fault loops in %
I
phmax
the maximum phase current in any of the three phases
By default, this setting is set excessively high to always enable phase-to-phase
measurement for phase-to-phase-ground faults. This default setting value must be
maintained unless there are very specific reasons to enable phase-to-ground
measurement. Even with the default setting value, phase-to-ground measurement is
activated whenever appropriate, like in the case of simultaneous faults: two ground
faults at the same time, one each on the two circuits of a double line.
One specific situation where the 3I0Enable_PG setting should be altered is for cross-
country faults in high impedance grounded networks, in order to make sure that
operation is phase-to-ground. This is particularly important when using phase
preference logic, since it is only working per phase, not for phase-to-phase
measurement. The limit should be set so that it will be exceeded during a cross-country
fault.
8.12.3.10 ZMMMXU settings
GUID-42F340C5-93CC-40AE-B67D-DC1B7D0520DA v1
ZZer
oDb
Minimum level of impedance in % of range (ZMax-ZMin) used as indication of zero
impedance (zero point clamping). Measured values below ZZeroDb are forced to zero.
ZHiHiLim, ZHiLim, ZLowLim and ZLowLowLim
All measured values are supervised against these four settable limits. It provides the
attribute "range" in the data class MV (measured value) with the type ENUMERATED
(normal, high, low, high-high and low-low) in ZMFPDIS.ZMMMXU.
ZLimHys
1MRK 504 163-UUS A Section 8
Impedance protection
Transformer protection RET670 2.2 ANSI 395
Application manual
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