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
Test points X R
P1 ZxFwd · sin(LineAngle) ZxFwd · cos(LineAngle)
P2 ((ZxFwd -ZxRev / 2) · sin(LineAngle)) ZxFwd / 2 · (1 + cos(LineAngle) + ZxRev/2 · (1 –
cos(LineAngle))
P3 ((ZxFwd -ZxRev / 2) · sin(LineAngle)) -ZxFwd / 2 · (1 – cos(LineAngle) + ZxRev / 2 · (1
+ cos(LineAngle))
P4 -ZxRev · sin(LineAngle) -ZxRev · 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_Zx are activated
(where x is 2 or 3 depending on selected zone). After the trip time delay of the respective zone has
elapsed, also the signals TRIP and TRZx (where x is 2 or 3 depending on selected zone) shall be
activated.
Load encroachment
GUID-4E0958A9-000E-440F-A880-89B54774AC63 v3
Load encroachment operates on the same measuring principles as the impedance measuring zones.
Thus, it is necessary to follow the same principles as for distance protection when performing the
secondary injection tests. Measure operating characteristics during constant current conditions. Keep the
injected current as close as possible to the rated value of its associated input transformer or lower.
Ensure, however, that it is higher than 30% of the rated current. Ensure that the maximum continuous
Section 11 1MRK 504 165-UUS Rev. J
Testing functionality by secondary injection
166 Transformer protection RET670
Commissioning manual
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