Hitachi Relion 670 Series Applications Manual page 139

1MRK506375-UEN Rev. N
‐25 ‐18.75
IEC17000201 V1 EN-US
Figure 46:
Wrong phase coupling protection
There is a possibility of closing the extension CB in a neutral section even when the power supply is
present at both sides. In this case, a fault between two traction substations occurs. This maloperation
is known as 'wrong phase coupling' (WPC). In
current scenarios when the wrong phase coupling occurs. From the phasor diagram, it is clear that
the impedance locus of this fault lies in the second quadrant of the impedance plane as ϕ>90°. A
relay operation should be immune to the regenerating currents from the traction load. This is
achieved by shifting the characteristic to an offset from the R-axis.
Railway application RER670
Application manual
x
37.5
31.25
25
18.75
12.5
6.25
0
‐12.5 ‐6.25
‐6.25
IED operating characteristics
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Zone 1 Zone 2
6.25 12.5 18.75
Figure 47, the phasor diagram represents voltage and
Impedance protection
Zone 3
R
25 31.25 37.5
IEC17000201-1-en.vsdx
GUID-1E8BD367-8325-4238-8346-6C261B3CC9BC v1
Section 7
133