DC contactor principle of its operation and the exchange of contacts similar, but DC breaking the magnetic energy stored in the inductive load transient release of energy produced by the arc breakpoint, thus requiring the DC contactor interrupter has a certain function. Medium / large capacity DC contactor normally single breakpoint layout of the overall structure, which is characterized by long distance when breaking arc, arc chute containing the arc chute. Small capacity DC contactors using double-break three-dimensional arrangement.
When selecting contacts note the following.
1, the main contacts rated voltage ≥ rated load voltage.
2, the main contacts rated current ≥1.3 times the rated load current.
3, rated coil voltage. When the line is simple, when using less electrical appliances, the choice of 220V or 380V; when the circuit complexity, use of electrical appliances are more or less safe place, the choice of 36V, 110V or 127V.
4, the number of contacts of the contactor, the type should meet the requirements of the control circuit.
5, the operating frequency (hourly contact-off times). When the on-off switching frequency current is large and exceeds a predetermined value, the rated current should be used in a contactor model. Otherwise it would be a serious fever contact, even welded together, causing the motor and other load phase operation.