44x/EN AP/Hb6
-120 MiCOM P40 Agile
+
+ +
--
-
T
T
Pole Live Pole Dead
P0553ENa
+
+
--
T
P
ole
Live
Pole Dead
+
-
I
I
I<
I
<
Figure 90: Algorithm for pole dead detection
Description of the open pole detection algorithm:
Each half cycle after the current crosses zero, the algorithm detects whether the current is
higher than the I< threshold. If it is, then the detection timer is restarted, if it is lower than the
set value then nothing is done.
At the end of the detection timer, open pole decision is given by the algorithm.
Time delay value given by: (Number of Samples/2 + 2) * ((1/Freq)/Number of Samples)
Where:
T = 13,3 ms (50 Hz)
or
T = 11,1 ms (60 Hz)
The current used is the unfiltered current (only the analog low pass filter is used)
Example:
In the first example, the line current is broken by the opening of the circuit breaker.
The detection is confirmed 3ms after the pole is opened.
In the second example, some residual current remains due to the CT. The detection is
confirmed 12 / 15 ms after the pole is opened.
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