Vacuum contactor
Function of vacuum contactor: the vacuum arc extinguishing chamber is used to extinguish arc, which is used to frequently connect and cut off the normal working current. It is usually used to connect and cut off 6kV, 380V (660V, 1140V) AC motors that are frequently started and stopped in medium and low voltage from a long distance. Low voltage vacuum AC contactor is widely used in coal mine, electric power, metallurgy and textile. High rise buildings and other industries. Structure of vacuum contactor: mainly composed of vacuum arc extinguishing chamber and operating mechanism. The vacuum arc extinguishing chamber has two functions of reliable arc extinguishing when passing the normal working current and frequently cutting off the working current. However, overload current and short circuit current cannot be cut off. The operating mechanism is composed of a holding coil with an iron core and an armature. The coil is energized, the armature is attracted, and the contactor is closed; The coil loses power and the contactor is disconnected. The holding coil generally has two forms: DC and AC. The shell of the vacuum interrupter is made of glass or ceramic insulating materials, and the internal vacuum degree is usually above 0.01Pa. As there is less air in the shell, the contact opening can be very small, and the arc is easier to be extinguished. The contact material is generally made of copper, antimony, osmium and other alloys. The role of the shielding cover in the arc extinguishing chamber is to condense the metal vapor diffused from the contact gap when breaking the current, which is helpful for arc extinguishing, and also can prevent the metal vapor from splashing onto the insulation shell to reduce its insulation strength. The moving contact is connected with the lower end of the housing with a corrugated pipe. The moving contact can move up and down without air leakage. Operating principle of vacuum contactor: it is usually composed of insulated insulating frame, metal base, transmission crank arm, electromagnetic system, auxiliary switch, vacuum switch tube and other components. When the solenoid coil passes the control voltage, the armature drives the crank arm to rotate, so that the main contact in the vacuum switch tube is connected. After the solenoid coil is powered off, the main contact is disconnected due to the action of the opening spring.