Hitachi RET670 Commissioning Manual page 163

1MRK 504 165-UEN Rev. K
Z1Fwd
Z1Rev
LineAngle
Test points
P1
P2
P3
P4
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.
IEC11000313 V2 EN-US
Figure 46:
Where,
ZxFwd
ZxRev
LineAngle
Transformer protection RET670
Commissioning manual
is the forward positive sequence impedance setting for zone 1
is the reverse positive sequence impedance setting for zone 1
is the Impedance angle for phase-to-phase fault in degrees
X
Z1Fwd · sin(LineAngle)
((Z1Fwd -Z1Rev / 2) · sin(LineAngle))
((Z1Fwd -Z1Rev / 2) · sin(LineAngle))
-Z1Rev · sinLineAngle
X
P3
LineAngle
ZxRev
P4
Proposed four test points for phase-to-earth fault
is the forward positive sequence impedance setting for zone x (where, x is 2- 3 depending
on the zone selected)
is the reverse positive sequence impedance setting for zone x (where x is 2- 3 depending on
the zone selected)
is the Impedance angle for phase-to-phase fault in degrees
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R
Z1Fwd · cos(LineAngle)
Z1Fwd / 2 · (1 + cos(LineAngle) + Z1Rev / 2 · (1
– cos(LineAngle))
-Z1Fwd / 2 · (1 – cos(LineAngle) + Z1Rev / 2 ·
(1 + cos(LineAngle))
-Z1Rev · cos(LineAngle)
P1
ZxFwd
P2
IEC11000313-1-en.vsd
Section 11
Testing functionality by secondary injection
R
157