Main Parameters Of Molded Case Circuit Breaker

⑴ Rated voltage
The rated voltage on the circuit breaker nameplate refers to the rated voltage of the circuit breaker main contact, which is the voltage value that ensures the normal operation of the contactor contact for a long time.
(2) Rated current
The rated current on the contactor nameplate refers to the rated current of the circuit breaker main contact, which is the current value that ensures the normal operation of the contactor contact for a long time.
⑶ Tripping current
The tripping current is the current setting value that causes the overcurrent release to operate. When the circuit is short-circuited or the load is severely overloaded, and the load current is greater than the tripping current, the circuit breaker main contact will disconnect.
⑷ Overload protection current and time curve
The overload protection current and time curve are inverse time characteristic curves. The greater the overload current, the shorter the time for the thermal release to operate.
⑸ Rated voltage of undervoltage release coil
The rated voltage of the undervoltage release coil must be equal to the line rated voltage.
⑹ Rated voltage of shunt release coil
The rated voltage of the shunt release coil must be equal to the control power supply voltage.
⑺ Rated ultimate short-circuit breaking capacity Icu
There are two types of breaking capacity indicators for circuit breakers: rated ultimate short-circuit breaking capacity Icu and rated operating short-circuit breaking capacity Ics.
Rated ultimate short-circuit breaking capacity Icu is the breaking capacity limit parameter of the circuit breaker. After breaking several short-circuit faults, the breaking capacity of the circuit breaker will decrease.
Rated operating short-circuit breaking capacity Ics is a breaking indicator of the circuit breaker, that is, after breaking several short-circuit faults, it can still ensure its normal operation.
For molded case circuit breakers, Ics is qualified as long as it is greater than 25% Icu. Most of the Ics of circuit breakers on the market are between (50%-75%) Icu.
⑻ Current limiting breaking capacity
Current limiting breaking capacity refers to the ability of the circuit breaker to limit the fault current when the circuit breaker trips when a short circuit occurs in the circuit. When a short circuit occurs in the circuit, the circuit breaker contacts open quickly and generate an arc, which is equivalent to inserting a rapidly increasing arc resistor in series in the line, thereby limiting the increase of fault current, reducing the adverse effects of the electromagnetic effect, electrodynamic effect and thermal effect of the short-circuit current on the circuit breaker and electrical equipment, and extending the service life of the circuit breaker. The shorter the circuit breaker disconnection time, the better the current limiting effect, and the closer Ics is to Icu.