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Note that even though the maximum discordance value is shown under pole A, it does not
indicate that the maximum of the three discordance values is associated with pole A.
The discordance table does not appear in the HMI if the CB is a ganged breaker (only one
drive motor) and not an IPO breaker.
Separation speed & touching speed
A CB must operate at a specific speed in order to build up adequate pressure to allow for
the cooling stream of SF
separation.
To enable speed calculations, the system requires two key distances to be entered during
setup, measured in mm from the fully open position which is 0mm. In this example:
O
End of Open position = location of 52b sensor
C
End of Close position = location of 52a sensor
HMI: Settings/Opening and Settings/Closing
The difference between these two positions (C-O), in this example: 120-15=105mm, is
usually ~80% of the "stroke" of the circuit breaker. This stroke information will be found in
the CB manual. It is assimilated to the travel distance and the contact "separation speed" is
calculated by dividing this distance by the "opening travel time" (t2-t1) which has been
recorded.
Because there can be variation between the exact position of the 52a and 52b sensors
during manufacturing, it is recommended to set the opening position at 15mm and to adjust
the closing position to whatever distance is required for the speed calculated to match the
speed from the FAT or last tests performed. It should be approximately 0 to 30mm off from
"15mm + stroke length" value. See section 5.5.2 for more details.
A similar calculation is done for the closing contact "touching speed" by using the same
travel distance and the "closing travel time" (t2-t1) recorded.
HMI: Measurements/Last opening and closing results
All speeds are expressed in meters per second (m/s)
MA-037 - CB Watch 3 Operating Manual
gas to extinguish the arc that is generated after the contact
6
Figure 42 – Entry of key distances
Figure 43 – Separation and touching speed
v7.0 - May 2020
15mm here
120mm here
Page 31 of 118
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