The low-voltage apparatus in the distribution box is composed of fuse, AC contactor, residual current action protector, capacitor and meter. The upper limit of ambient air temperature shall not exceed 40 ℃; The average value of ambient air temperature in 24h shall not exceed 35 ℃; The lower limit of ambient air temperature shall not be lower than - 5 ℃ or - 25 ℃. Due to improper selection of AC contactor capacity during manufacturing, AC contactors with the same capacity are installed for different outgoing circuits, and the imbalance of three-phase load is not considered, so the current level of some outgoing contactors cannot be increased by one current level based on the normal selection model, The protection circuit is adopted to prevent the failure of the external circuit powered by the distribution box. Select the intelligent phase loss protector with small volume. For example, da88cm-ii motor phase loss protection module can be selected and installed in the distribution box to prevent the motor from burning out due to low-voltage phase loss operation.

Select energy-saving AC contactor (similar to cj20si), pay attention to the connection between the coil voltage of AC contactor and the corresponding terminal selected as current action protector, and pay attention to correct load matching. When selecting AC contactor, products with insulation grade of class A or above shall be selected, and the rated current of its main circuit contact must be greater than or equal to the load current of the controlled line. The rated voltage of the electromagnetic coil of the contactor is 380V or 220V, and the selection of residual current action protector.