P1
P3
P4
X
R
LineAngle
Z1Fwd
Z1Rev
P2
IEC11000312-2-en.vsd
IEC11000312 V2 EN-US
Figure 45: Proposed four test points for phase-to-phase fault
Where,
Z1Fwd
is the forward positive sequence impedance setting for zone 1
Z1Rev is the reverse positive sequence impedance setting for zone 1
LineAngle is the Impedance angle for phase-to-phase fault in degrees
Test points X R
P1 Z1Fwd · sin(LineAngle) Z1Fwd · cos(LineAngle)
P2 ((Z1Fwd -Z1Rev / 2) · sin(LineAngle)) Z1Fwd / 2 · (1 + cos(LineAngle) + Z1Rev / 2 · (1 –
cos(LineAngle))
P3 ((Z1Fwd -Z1Rev / 2) · sin(LineAngle)) -Z1Fwd / 2 · (1 – cos(LineAngle) + Z1Rev / 2 · (1
+ cos(LineAngle))
P4 -Z1Rev · sinLineAngle -Z1Rev · cos(LineAngle)
Change the magnitude and angle of phase-to-phase voltage, to achieve impedances at test points P1,
P2, P3 and P4. For each test point, observe that the output signals, PICKUP and PU_Z1 are activated
where x refers to the actual phase to be tested. After the trip time delay for the zone 1 has elapsed, the
signals TRIP and TRZ1 shall be activated.
To verify zone 2 and zone 3 mho characteristic, at least two points must be tested. The default measuring
loop selected is maximum current phase to current loop. Hence the below characteristics are tested with
phase–to-ground fault conditions.
1MRK 504 165-UUS Rev. J Section 11
Testing functionality by secondary injection
Transformer protection RET670 165
Commissioning manual
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