The miniature circuit breaker (MCB) for rural lighting electrical ready boards in Africa complies with the IEC 60898 standard, and the electromagnetic trip (instantaneous magnetic trip) during short circuit is required to operate within 0.1 seconds, which is also a commonly used technical indicator for Eskom rural lighting boxes. The electrical ready board faces the end lighting circuit and mainly uses C-type micro circuit breakers. The instantaneous tripping interval is 5-10 times the rated current. After reaching the action threshold, the electromagnetic mechanism trips quickly without delay. Most of the measured action times are only 0.01-0.04 seconds, far less than the 0.1 second limit.

The working conditions of rural power grids in Africa are complex, with large voltage fluctuations, long lines, and limited grounding conditions. Short circuit faults are prone to arcing, wire erosion, and terminal damage inside the box. Electromagnetic tripping relies on the magnetic force generated by short-circuit high current to directly drive the tripping mechanism, which is different from the inverse time delay characteristics of thermal tripping, and is specifically designed to deal with malignant faults such as short circuits. A time limit of 0.1 seconds can quickly cut off faults, limit arc energy, reduce the risk of lighting electrical ready board fire, insulation breakdown, and electric shock, and meet the electrical safety protection needs of rural personnel.

In the project acceptance test, it is necessary to verify at 10 times the rated short-circuit current to ensure that the circuit breaker can reliably trip within 0.1 seconds; Under the condition of 5 times the rated current, non instantaneous action is allowed to avoid the impact current of the lighting circuit and prevent false tripping. At the same time, the overall fault protection of the electrical Ready Board Box also needs to be coordinated with the impedance verification of the grounding circuit. The longest power-off requirement for the TN system end lighting circuit fault is 0.4 seconds, and the 0.1 second electromagnetic trip index is the core hard constraint, which balances the protection sensitivity and power supply stability, and meets the requirements of outdoor, high dust and humidity distribution environments in Africa.