There are different essential parameters of the circuit breakers which necessary to understand. Furthermore, These parameters we often see marked on circuit breakers.
The characteristics of circuit breakers mainly include: rated voltage Ue; rated current In; overload protection (Ir or Irth) and short-circuit protection (Im) trip current setting range; rated short-circuit breaking current (industrial circuit breaker Icu; household circuit breaker Icn) )
Operating Voltage (Ue)
It is the voltage at which any circuit breaker is designed under normal conditions.
Rated current (In)
This is the maximum value of current that a circuit-breaker, can carry indefinitely at an ambient temperature designed by the manufacturer, without any interruption.
Read Also: How to Read Nameplate of MCB (Miniature Circuit Breaker)?
However, These are the parameters which need to understand by every electrical engineer.
Overload Trip (Ir) Setting:
It is used for the continuous ampere rating according to current. Moreover, It has different set of multiples in the adjustable knob ranging from 0.4 to 1 of nominal or rated current of circuit breaker which can be represented by In.
Ir= multiple *In.
Let suppose we have a circuit breaker having rating of 2000 A which has a current load of 1000A so we will set it 1000A by moving the knob at 0.5 which means
Ir = 1000A
Hence, After exceeding 1000A of load it will trip the Circuit Breaker and will disconnect the load.
Short-circuit relay trip current setting value (Im):
The short-circuit trip relay (instantaneous or short delay) is used to quickly trip the circuit breaker when a high fault current value occurs, and its trip limit Im.