ABB Relion 670 series - Page 270

IEC05000182-2-en.vsdx
R
X
R
X
R
X
Non-directional Forward Reverse
IEC05000182 V2 EN-US
Figure 126: Directional operating modes of the distance measuring zones
7.6.6.3 Minimum operating current
GUID-BFD07CBE-F322-4602-A3BC-B6E8D72DB92B v1
The operation of Distance measuring zones, quadrilateral characteristic (ZMRPDIS, 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 can 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
7.6.6.4 Measuring principles
M16923-4 v7
Fault loop equations use the complex values of voltage, current, and changes in the current.
Apparent impedances are calculated and compared with the set limits. The apparent impedances
at phase-to-phase faults follow equation
64 (example for a phase A to phase B fault).
=
V
A
- V
B
Z
app
I
A
- I
B
EQUATION1545 V1 EN-US
(Equation 64)
Section 7 1MRK 502 066-UUS B
Impedance protection
264
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