Features of a Circuit Breaker.

The characteristics of the circuit breaker are: rated voltage Ue; Rated current In; Trip current setting range for overload protection (Ir or Irth) and short circuit protection (Im); Rated short-circuit breaking current (industrial circuit breaker Icu; Home circuit breaker Icn), etc.

1. Rated operating voltage (Ue) : This is the voltage at which the circuit breaker operates under normal (uninterrupted) conditions.

2. Rated current (In) : This is the maximum current value that the circuit breaker equipped with a special overcurrent trip relay can withstand indefinitely at the ambient temperature specified by the manufacturer, and will not exceed the temperature limit specified by the current bearing part.

3. Short-circuit relay trip current setting (Im) : short-circuit trip relay (instantaneous or short delay) is used to make the circuit breaker quickly trip when the high fault current value occurs, and its trip limit Im.

4. Rated short-circuit breaking capacity (Icu or Icn) : The rated short-circuit breaking current of the circuit breaker is the highest (expected) current value that the circuit breaker can break without being damaged. The current value provided in the standard is the root mean square value of the AC component of the fault current, and the DC transient component (which always occurs in the worst case of short circuit) is assumed to be zero when calculating the standard value. Industrial circuit breaker ratings (Icu) and domestic circuit breaker ratings (Icn) are usually given in the form of kA root mean square values.

5. Short circuit breaking capacity (Ics) : The rated breaking capacity of the circuit breaker is divided into two types: rated limit short circuit breaking capacity and rated operating short circuit breaking capacity.