CB Watch 3 User Manual v6.3 - May 2019 Page 52 of 100
Any alarm raised can be seen in the HMI:
HMI: Measurements / Alarms
Figure 76 – Max arcing time threshold
Arcing contact wear
Contact electrical wear
During the period from the separation of the contacts (time Ts) and until definitive
extinction of the current (time Ta), we cumulate the squared amps interrupted by the
circuit breaker to estimate the electrical deterioration induced by the operation. We do
that independently for each phase/pole.
Electrical contact wear per operation = (Irms).(i(t))
2
dt
The function above is set by default to: f(Irms)=1 for all Irms values.
The calculated value above represents the electrical deterioration for the operation under
consideration. It is then added to the cumulative figure to obtain the total electrical wear
per phase that the contact has endured so far.
Cumulative electrical contact wear = Electrical contact wear per operation
The cumulative electrical contact wear is displayed in the HMI after each operation:
HMI: Measurements / last opening results
Figure 77 – Contact electrical wear cumulative value
When the arcing contacts are replaced with new ones, the cumulative arcing contact
wear needs to be reset to zero here:
HMI: Settings / Opening
Figure 78 – Initial electrical wear setting
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