ABB RET670 Commissioning Manual page 176

Section 11
Testing functionality by secondary injection
170
X
P3
ZxRev
P4
IEC11000313 V2 EN-US
Figure 43: 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
ZxFwd · sin( LineAngle )
P1
ZxFwd - ZxRev / 2) · sin( LineAngle ))
P2 ((
ZxFwd - ZxRev / 2) · sin( LineAngle ))
P3 ((
ZxRev · sin( LineAngle )
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 STZx are activated (where x is 2 or 3 depending on selected zone).
After the operate 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
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
P1
ZxFwd
P2
LineAngle
IEC11000313-1-en.vsd
R
ZxFwd · cos( LineAngle )
ZxFwd / 2 · (1 + cos( LineAngle ) +
ZxRev /2 · (1 – cos( LineAngle ))
ZxFwd / 2 · (1 – cos( LineAngle ) +
-
ZxRev / 2 · (1 + cos( LineAngle ))
ZxRev · cos( LineAngle )
-
Transformer protection RET670 2.2 IEC
1MRK 504 165-UEN A
R
GUID-4E0958A9-000E-440F-A880-89B54774AC63 v3
Commissioning manual