Commissioning P54x/EN CM/La4
MiCOM P543, P544, P545 & P546
CM) 10-51
CM
R
Z5
Z6
Z5'
Z6'
R5 R6R5'R6'
+jX
∆R
State 1
State 2
State 3
State 4
P1982ENa
Figure 6 Four state impedances
Depending on the Out of Step settings, follow one of the three options.
8.4.9.1 Predictive OST setting
Clea
r all alarms. Set Tost to zero. Based on healthy voltages (VA = VB = VC = 57.8V)
calculate the currents to generate the impedances as per Table 11.
State 1 State 2 State 3
Apply IA = IB = IC =
61.1
8.57
R
)56(
2
1
5
8.57
RRR
59.0
8.57
R
Angle 0° 0° 0°
Duration 500 ms
Longer than 25 ms but
shorter that ‘Delta t’ set time
500 ms
Table 11: Predictive OST state sequence
Note: Angle in the table above is the angle between voltages and their
respective currents.
Now apply the 3 state sequence to the relay under test and observe that the relay has
tripped 3 phase and that an associated ‘Predictive OST’ alarm is displayed on the local LCD.
Clear all alarms.
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