CB Watch 3 User Manual
v6.3 - May 2019
Page 57 of 100
DC supply alarm
An alarm can be set for each of the DC voltage sources with both a minimum and
maximum threshold. Any alarm is displayed in the HMI.
HMI: Settings / Analogue channels
Figure 86
–
DC voltage alarm thresholds
HMI: Measurements / Alarms
Figure 87
–
DC voltage alarms
Coil Integrity
Coil current
With the appropriate CTs installed, the CBW3 can measure the current passing through
each coil during an opening or closing operation. This is useful data to measure the
integrity of the coil. Any partial reduction in the number of turns (reducing the ability of
the coil to trip the latch) will change the impedance of the coil and will be detected
through a resulting increase in the current used and a lengthening of the time to reach
actuation level.
A small degradation of the coil can therefore be detected before it becomes problematic
and the coil becomes open circuit, preventing the open/trip or close command from the
protection relay being executed.
The following information is displayed in the HMI:
HMI: Measurement / Last opening results or last closing results
Figure 88
–
Coil currents and coil charges
Two values are displayed for each pole, for the opening coils being used (open1 or open2)
and for the closing coils: