MA-037 - CB Watch 3 Operating Manual
v7.0 - May 2020
Page 27 of 118
For an IPO CB, if the 52a or 52b contacts do not show the same value for all 3 poles for
longer than the
“Pole discrepancy
timeout
”
(by default: 1 second),
then the “pole
d
iscrepancy”
alarm is also raised.
This alarm can serve as a reminder of a temporary phase imbalance in an IPO CB (e.g. one
phase is open while the others are not) and that the situation should not be maintained for
a long time.
HMI: Measurements/Alarms
Figure 32
–
Pole discrepancy alarm
The pole discrepancy timeout can be adjusted:
HMI: Settings/Operations monitoring
Figure 33
–
Setting the pole discrepancy timeout
Previous operation
The type
of operation that was just performed is indicated as “previous operation type”.
This can be Opening (O), Closing (C) or a combination operation (CO, OC, OCO).
During each operation, data acquisition is performed from all the sensors for a period of
0.3s (300ms).
When a current flowing to the coil is detected, the system then samples every 0.4ms for
300ms, we get a total number of sample of 300 / 0.4 = 750. By analysing the data from the
52a and 52b contact during this sampling period, we determine the type of operation that
has occurred using the following rules:
If the system sees a Closing operation first, it will check for another Opening operation
during the sampling time
If it does not see one, then it declares a simple Closing operation “C”
If it does see one, then it declares a Closing-
Opening operations “CO”
If the system sees an “Opening” operation first, it will check for another Closing
operation
during the sampling time
If it does not see one, then it declares a simple Opening operation “O”
If it does see one, then it continues to see if there might be a third operation during
the sampling period
If it does not see one, then it declares an Opening-
Closing operation “OC”
If it does see one, then it declares an Opening-Closing-Opening operation
“OCO”
HMI: Measurements/Sensors
