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Measurements » Breaker Measurements
1. CB Measurements window monitors and records all of the circuit breaker activity. The window displays:
Durations of the last closing and tripping operations, in seconds;
Total tripping numerator;
Cumulative total tripping current for each of R, S and T phases, in amperes (A);
Cumulative total tripping current-square for each of R, S and T phases, in amperes-square (A²).
Trip and Closing Time values are of great importance for administrators to supervise the circuit breaker
mechanism condition. During evaluations, it must be kept in mind that the values shown are the measured
delays between the excitation of trip / closing release coils and loss / receive of signals from the normally
open auxiliary contact of the CB. Note that, assigning 52a to any of the programmable inputs and cabling a
normally open auxiliary contact of the CB to that input is essential for the functionality of Trip and Closing
Time monitors.
Total Trips, Total A and Total A
2
measurements are the values that the administrator can use to evaluate
mechanical and electrical maintenance periods. Total A
2
values are usually utilized for CBs with rated
voltage 36 kV or lower, while Total A values are evaluated for determination of maintenance periods of
CBs with rated voltage 52k V or higher. Documentation of the CB’s manufacturer must be examined to
decide whether to supervise Total A or Total A² values for a given CB. □
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