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

Rated current (In): The maximum current that a circuit-breaker equipped with a special overcurrent relay can withstand indefinitely at the ambient temperature specified by the manufacturer, without exceeding the temperature limit specified for the current-carrying parts.

Short-circuit tripping current setting (Im): the short-circuit tripping relay (instantaneous or with short delay) is used to trip the circuit-breaker quickly when a high fault current occurs and its tripping limit is 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 residential 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.