Opening time:
The opening time is the interval of time from energizing of the opening release (e.g. opening coil) for a circuit breaker being in closed position and the instant when the (arcing) contacts have separated in all poles.
Closing time:
The closing time is the interval of time from energizing of the closing release (e.g. closing coil) for a circuit breaker being in open position and the instant when the (arcing) contacts touch in all poles.
Rated break time:
The rated (maximum) break time (interrupting time) is the time interval between energizing the trip circuit and when the arc is extinguished in all poles.
The break time is expressed in ms or cycles (20 ms = 1 cycle at 50 Hz).
Dead time:
The dead time (during auto-reclosing) is the interval of time between final arc extinction in all poles in the opening operation and the first re-establishment of current in any pole in the subsequent closing operation.
IEC and ANSI/IEEE specifies a dead time of 300 ms.
Arcing time:
Interval of time between the instant of the first initiation of an arc and the instant of final arc extinction in all poles.
Pre-arcing time:
Interval of time between the initiation of current flow in the first pole during a closing operation and the instant when the contacts touch in all poles for three-phase conditions and the instant when the contacts touch in the arcing pole for single-phase conditions.
Reclosing time:
The reclosing time is the interval of time between the energizing of the opening release (e.g. opening coil) and the instant when the contacts touch in all poles during a reclosing cycle.
If the differences in operating times (closing and opening time respectively) between poles are small and can be neglected, the following approximative formula can be applied:
Reclosing time = Opening time + Arcing time + Dead time +
Pre-arcing time
Close-Open time:
The close-open time is the interval of time between the instant of contact touch in the first pole during a closing operation and the instant when the (arcing) contacts have separated in all poles during the following opening operation.
The opening release (e.g. opening coil) shall have been energized at the instant when the contacts touch during closing (CO-operation without any intentional time delay; pre-tripped CO-operation).
NOTE: The close-open time is not equal to Closing time + Opening time.
Open-Close time:
The open-close time (during auto-reclosing) is the interval of time between the instant of contact separation in all poles and the instant when the contacts touch in the first pole in the subsequent closing operation.
If the differences in operating times (closing and opening time respectively) between poles are small and can be neglected, the following approximative formula can be applied:
Open-Close time = Arcing time + Dead time + Pre-arcing time
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