Working Principle and Advantages of Vacuum Contactor

The vacuum contactor uses the failure of the vacuum interrupter to extinguish the arc，so to be used frequently switch on and off the normal working current. Usually used for remote connection and disconnection the medium and low voltage 6kV、380V(660V、1140V) motors that needs frequent start and stop .

Overview

The series of low-voltage vacuum AC contactors are widely used in various industries such as coal mines, electric power, metallurgy, textiles, and high-rise buildings.

Low-voltage vacuum AC contactors are suitable for AC: 50HZ，Rated voltage: 1140V, rated current 63 to 630A feeder network, for remote connection and disconnection of circuits, and frequent start and stop of AC motors. It is especially suitable for assembly with various protection devices to form a flameproof electromagnetic starter.

Composition

The vacuum contactor is mainly composed of a vacuum interrupter and an operating mechanism. The vacuum interrupter has two functions of passing the normal working current and reliable arc extinguishing when frequently cutting off the working current . However, the 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. When the coil is energized, the armature is attracted, and the contactor is closed; when the coil is de-energized, the contactor is disconnected. There are two types of holding coils: DC and AC.

The outer shell of the vacuum interrupter is made of glass or ceramic insulating material, and the internal vacuum is usually above 0.01Pa. Since there is less air in the shell, the contact spacing can be made small, and the arc is easier to extinguish. The contact material is generally made of alloys such as copper, antimony, and osmium. The function of the shielding cover in the arc extinguishing chamber is to condense the metal vapor diffused in the contact gap when the current is interrupted, which helps to extinguish the arc, and can also prevent the metal vapor from splashing on the insulating shell to reduce its insulation strength. The movable contact is connected with the lower end of the shell by a bellows, and the movable contact can move up and down without air leakage.

Working principle

The vacuum contactor is usually composed of an insulating frame, a metal base, a driving arm, an electromagnetic system , an auxiliary switch, and a vacuum switch tube. When the electromagnetic coil passes the control voltage, the armature drives the turning arm to rotate, so that the main contact in the vacuum switch tube is connected. After the electromagnetic coil is de-energized , the main contact is broken due to the action of the opening spring.

The vacuum switch tube is composed of an upper cover, a lower cover, a metal bellows and a ceramic tube. The outer shell of the vacuum switch tube is made of 95 porcelain insulating material to make a corrugated porcelain tube. It has a large creepage distance and high mechanical strength. , Heat resistance and impact resistance. A pair of dynamic and static contacts are encapsulated in the vacuum switch tube. The contact material is made of wear-resistant and low-cutting value Cu-W-Wc, so that under the condition of satisfying the breaking performance, the overvoltage caused by the blocking during the breaking process is reduced . Improve the service life of the vacuum switch tube. When the metal bellows moves axially, the moving contact is driven to open and close.

The electromagnetic system considers the actual suction characteristics and the reaction force characteristics to be well matched, as well as the advantages of low noise and power saving during the operation of the contactor. The retained double coil is composed of two windings for starting and maintaining . It is switched by an auxiliary switch to facilitate the user's communication. Power supply operation, the contactor has a bridge rectifier device.

Mechanical lock: When the closed coil is energized, the contactor is closed, and the mechanical lock is locked: When the trip coil is energized, the mechanical lock is tripped and the contactor is released. When the trip coil is in hot state, its voltage is Us85 The contactor can be reliably released within the range of %-110%.

Shaanxi Joyelectric International Co., Ltd. is a leading power and energy system products supplier in China.our main products include 12kV/24kV/36kV/40.5kV/145kV circuit breaker, switchgear & RMU as well as relative main components and accessories.we also are capable of offering customized innovation, design, product manufacturing and excellent service.And our products widely used in various industries such as coal mines, electric power, metallurgy, textiles, and high-rise buildings.

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