(1) Select the type of contactor based on the nature of the load.

(2) The rated voltage should be greater than or equal to the operating voltage of the main circuit.

(3) The rated current should be greater than or equal to the rated current of the controlled circuit. For the load of the electric motor, it should be appropriately increased or decreased according to its operating mode.

(4) The rated voltage and frequency of the attraction coil should be consistent with the selected voltage and frequency of the control circuit.