ABB Relion 670 series - Minimum operating current

en05000182.vsd
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Non-directional Forward Reverse
IEC05000182 V1 EN
Figure 92: Directional operating modes of the distance measuring zone
6.2.2.3 Minimum operating current
The operation of Distance measuring zone, quadrilateral characteristic for series
compensated lines (ZMCPDIS,ZMCAPDIS, 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 3I0.
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
201
Technical reference manual