and reverse direction (there are different forward and reverse settings - Zx and ZxRev
respectively, where x = 1 - 5). Therefore, all reach settings apply to both directions.
en05000182.vsd
R
X
R
X
R
X
Non-directional
Forward
Reverse
IEC05000182 V1 EN
Figure 78:
Directional operating modes of the distance measuring zones
6.1.3.3
Minimum operating current
The operation of Distance measuring zones, quadrilateral characteristic (ZMQPDIS,21)
is blocked if the magnitude of input currents fall below certain threshold values.
The phase-to-ground loop AG (BG or CG) is blocked if IA (IB or IC) <
IMinPUPG
.
For zone 1 with load compensation feature the additional criterion applies, that all phase-
to-ground loops will be blocked when IN <
IMinOpIR
, regardless of the phase currents.
IA (IB or IC) is the RMS value of the current in phase IA (IB or IC). IN is the RMS
value of the vector sum of the three-phase currents, that is, residual current 3I
0
.
The phase-to-phase loop AB (BC or CA) is blocked if I
AB (BC or CA)
<
IMinPUPP
.
All three current limits
IMinPUPG
,
IMinOpIR
and
IMinPUPP
are
automatically reduced to 75% of regular set values if the zone is set to
operate in reverse direction, that is,
OperationDir
=
Reverse
.
1MRK505222-UUS C
Section 6
Impedance protection
179
Technical reference manual
Summary of Contents for Relion 670 series
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