The main characteristics of circuit breakers are: Rated voltage UE, rated current in, overload protection (IR or Irth) and short-circuit protection (Im) of the tripping current setting range, rated short-circuit-break current (industrial circuit breaker ICU; household circuit breaker ICN).
Rated operating voltage (UE): This is the voltage that the circuit breaker works under normal (uninterrupted) conditions.
Rated current (in): This is the maximum current value that the circuit breaker with a dedicated overcurrent tripping 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.
Short-circuit Relay tripping current setting (IM): Short-circuit trip relay (instantaneous or short delay) for high fault current values when the circuit breaker quickly tripping, its trip limit Im. Rated short-circuit breaking capacity (ICU or ICN): the rated short-circuit breaking current of a circuit breaker is the highest (expected) current value that the circuit breaker can break without being compromised. The current value provided in the standard is the RMS value of the AC component of the fault current, and the DC transient component (which always appears in the worst case) when calculating the standard value is assumed to be zero. Industrial Circuit Breaker Ratings (ICU) and household circuit breaker ratings (ICN) are usually given in the form of Ka RMS values.