ABB RET670 Commissioning Manual page 141

1MRK 504 154-UUS B
To verify the zone 1 mho characteristic, at least two points must be tested.
IEC11000312 V2 EN-US
Figure 33: Proposed four test points for phase-to-phase fault
Where,
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, 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.
Commissioning manual
X
P3
LineAngle
Z1Rev
P4
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 · sin LineAngle
-
P1
Z1Fwd
P2
R
IEC11000312-2-en.vsd
R
Testing functionality by secondary injection
Z1Fwd · cos( LineAngle )
Z1Fwd / 2 · (1 + cos( LineAngle ) + Z1Rev / 2 · (1 –
LineAngle ))
cos(
- Z1Fwd / 2 · (1 – cos( LineAngle ) + Z1Rev / 2 · (1
+ cos( LineAngle ))
Z1Rev · cos( LineAngle )
-
Section 10
135