Rated operating voltage (Ue): This is the voltage at which the circuit breaker
operates under normal (uninterrupted) conditions.
Rated current (In): The maximum current value that a circuit breaker equipped with a special over-current 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 parts.
Short-circuit relay tripping current setting value (Im): short-circuit tripping relay (instantaneous or short delay) is used to make the circuit breaker trip quickly when a high fault current value occurs, and its tripping 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 at which the circuit breaker can break without being damaged. The current values given in the standard are the rms value of the ac component of the fault current, and the dc transient component (which always occurs in the worst case of a 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 kA rms.
Short-circuit breaking capacity (Ics): The rated breaking capacity of a circuit breaker is divided into two types: rated ultimate short-circuit breaking capacity and rated operating short-circuit breaking capacity.