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.