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, START and STZ1 are
activated where x refers to the actual phase to be tested. After the operate 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.
P1
P3
P4
X
R
LineAngle
ZxFwd
ZxRev
P2
IEC11000313-1-en.vsd
IEC11000313 V2 EN-US
Figure 46: Proposed four test points for phase-to-earth fault
Where,
ZxFwd
is the forward positive sequence impedance setting for zone x (where, x is 2- 3 depending
on the zone selected)
ZxRev is the reverse positive sequence impedance setting for zone x (where x is 2- 3 depending on
the zone selected)
LineAngle is the Impedance angle for phase-to-phase fault in degrees
1MRK 504 165-UEN Rev. K Section 11
Testing functionality by secondary injection
Transformer protection RET670 157
Commissioning manual
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