What is the selection criterion of Circuit Breakers for the Capacitor bank application.


31 January 2023

The selection should be done after derating the Circuit Breaker taking into consideration voltage variation and capacitors tolerances that could increase nominal current up to 1.5In.
The Derating factor of 1.5In
Where In = Q/ ( Square root of 3 ) Un
      Q = Capacitor Power
      Un = Nominal Voltage
Choose the Micrologic with delay time selection, so that the Circuit Breaker does not trip due to initial high inrush current.
Also to be taken into account are the parameters like supply frequency, operating voltage & harmonics level of the power system for such application.
Refer the attached sheet for further details for selection of Circuit Breaker for Capacitor duty application.
Note: Use the phase barrier between the phases in Circuit Breaker to prevent flashover due to heavy inrush current.