Which overcurrent protective devices will always have an instantaneous trip component as part of their Time-Current Characteristic?

Which overcurrent protective devices will always have an instantaneous trip component as part of their Time-Current Characteristic?

• A. ICCB and MCCB
• B. Only MCCB
• C. Only ICCB
• D. Neither ICCB nor MCCB

Answer: (A)

Time-Current Characteristics include an instantaneous trip portion that activates when fault current is very high. This immediate action protects equipment by opening the circuit almost at once during a short circuit. Both molded case circuit breakers (MCCB) and insulated/cased breakers (ICCB) are designed with this instantaneous trip feature, so they will trip without delay when the current exceeds a high, fixed threshold. The rest of the curve handles overloads over a longer period, but the instantaneous path is always present for short-circuit conditions in these devices. That’s why both MCCB and ICCB have an instantaneous trip component as part of their Time-Current Characteristic.

Time-Current Characteristics include an instantaneous trip portion that activates when fault current is very high. This immediate action protects equipment by opening the circuit almost at once during a short circuit. Both molded case circuit breakers (MCCB) and insulated/cased breakers (ICCB) are designed with this instantaneous trip feature, so they will trip without delay when the current exceeds a high, fixed threshold. The rest of the curve handles overloads over a longer period, but the instantaneous path is always present for short-circuit conditions in these devices. That’s why both MCCB and ICCB have an instantaneous trip component as part of their Time-Current Characteristic.