1. DC contactors type DC contactors types according to the load current type and level of load to select, that is AC or DC loads are light loads, loads or heavy load.
2. DC contactor main contact rated current of DC contactor main contact rated current can be calculated according to the formula IN main contact ≥/PN motor (1~1.4) UN motor contactor controlled motor starting and braking or reverses frequently will normally contactor main contact rated current reduced level.
3. Main contact contact rated voltage marked on the nameplate voltage means the main contact can withstand the rated voltage is not a coil voltage, use the main contacts of the contactor when rated voltage rated voltage shall be not less than the load.
4. Operating frequency selection of operating frequency means contactors switching times per hour. when switching large currents and switching frequency is too high, can cause contact severe overheating, even welding. operating frequency exceed the regulation value, high level DC contactors rated current should be used.
5. Coil voltage select coil rated voltage is not necessarily equal to the rated voltage of the contact, when the line is simple, using electric youth, 380V or 220V voltage directly, if the line is complex, using electrical 5h, 24V, 48V, 110V-voltage (1964 international provisions to 36V and 110V, 127V) coil.