DC contactors are mainly used for program-controlled power supply or uninterrupted power supply systems, forklifts, electric vehicles, and engineering machinery systems.
　　The selection method of DC contactor.
1. Choosing the type of DC contactorThe type of DC contactor should be selected according to the type of load current and the weight of the load, that is, whether it is an AC load or a DC load, light load, general load or heavy load.
2. The rated current of the main contact of the DC contactor The rated current of the main contact of the DC contactor can be calculated according to the empirical formula. IN main contact≥PN motor/(1~1.4)UN motor If the motor controlled by the DC contactor starts, brakes or Frequent reversal, generally reduce the rated current of the main contact of the contactor by one level.

Talking about the arc extinguishing method of DC contactor
3. Rated voltage of the main contactThe voltage marked on the nameplate of the contactor refers to the rated voltage that the main contact can withstand, not the voltage of the attracting coil.The rated voltage of the main contact of the contactor should not be less than the rated voltage of the load during use.
　　4. The selection of operating frequency The operating frequency refers to the number of times the contactor is turned on and off per hour. When the on-off current is large and the on-off frequency is too high, it will cause serious overheating of the contacts and even welding. If the operating frequency exceeds the specified value, it should be Choose a DC contactor with a rated current one level higher.
　　 5. Selection of the rated voltage of the coil The rated voltage of the coil is not necessarily equal to the rated voltage of the main contact. When the circuit is simple and there are few electrical appliances, you can directly choose the voltage of 380V or 220V. If the circuit is complicated and the electrical appliances are used for more than 5 hours, 24V, 48V or 110V can be used. Coil of voltage (36V, 110V, or 127V according to international regulations in 1964)