![GE CB Watch 3 Operating Manual Download Page 77](http://html.mh-extra.com/html/ge/cb-watch-3/cb-watch-3_operating-manual_122811077.webp)
MA-037 - CB Watch 3 Operating Manual
v7.0 - May 2020
Page 77 of 118
Figure 123
–
Control circuit monitoring alarms
Threshold values
DC Voltage Supply
This depends on what acceptable level has been set as a policy or what minimum voltage is
required by the coils. Normally, low voltage tests are run during the CB FAT and the lowest
tested value could be used as the minimum alarm level. High level alarm is much less of a
concern and can be effectively de-activated by using a very high threshold like 500V.
If this function is not being monitored and no sensor is present, then the values should be
set as such to avoid any erroneous alarm:
HMI: Settings / Analogue channels
Figure 124
–
DC voltage default settings
Mean coil current
Using historical data, we can determine the minimum and maximum values of the mean coil
current recorded. We can use them, as shown in the table below, to calculate the max
threshold for both opening and closing operation:
Opening
Closing
Nominal DC Voltage
A
Coil resistance
C
D
Max mean coil current
(A/C)x((100+p)/100)
(A/D)x((100+p)/100)
Figure 125
–
Mean coil current max threshold calculation
Min Alarm Max Alarm
Digital
Relay
Coil circuit DC voltage source 1
Yes
Yes
Yes
Yes
Coil circuit DC voltage source 2
Yes
Yes
Yes
Yes
Mean coil current - Open 1, per pole
No
Yes
Yes
Mean coil current - Open 2, per pole
No
Yes
Yes
Mean coil current - Close, per pole
No
Yes
Yes
Yes
Coil actuation charge - Open 1, per pole
Yes
Yes
Yes
Coil actuation charge - Open 2, per pole
Yes
Yes
Yes
Coil actuation charge - Close, per pole
Yes
Yes
Yes
Yes
Coil continuity - Open 1, per pole
Coil continuity - Open 2, per pole
Coil continuity - Close, per pole
Data obtained from CBW3
Yes
Yes
Yes
Thresholds
Alarms available
Yes
Yes