The composition and principle of vacuum contactor

1. Composition of vacuum contactor
AC vacuum contactor is mainly composed of electromagnetic system, contact system, arc extinguishing system and other parts.
1.1 Electromagnetic system: electromagnetic system includes electromagnetic coil and core, which is an important part of vacuum contactor, relying on it to drive the closing and breaking of contacts.
1.2 Contact system: contact is the executive part of vacuum contactor, including main contact and auxiliary contact. The role of the main contact is to connect and break the main circuit and control the larger current, while the auxiliary contact is in the control circuit to meet the requirements of various control modes.
1.3 Arc extinguishing system: The arc extinguishing device is used to ensure that when the contact breaks the circuit, the resulting arc is reliably extinguished, reducing the damage of the arc to the contact. In order to quickly extinguish the arc when disconnected, usually vacuum contactors are equipped with an arc extinguishing device, generally using a half-sealed longitudinal seam ceramic arc extinguishing cover, and equipped with a strong magnetic arc blowing circuit.
1.4 Other parts: insulated shell, spring, short circuit ring, transmission mechanism, etc.

2. The working principle of vacuum contactor
When the electromagnetic coil of AC vacuum contactor is not energized, the reaction force of the spring and the self-weight of the armature core make the main contact keep the open position.
When the electromagnetic coil is connected to the control voltage through the control circuit (generally rated voltage), the electromagnetic force overcomes the reaction force of the spring to suck the armature to the static iron core, driving the main contact to close and turn on the circuit, and the auxiliary contact then acts.

3. The structural characteristics of the vacuum contactor
3.1 Contactor consists of magnetic system, contact system, and auxiliary contact.
3.2 The contactor is arranged in three-dimensional structure, the upper part is contact system, the lower part is electromagnetic system.
3.3 The magnetic system consists of coil, core and rectifier, which is installed in the base made of cast aluminum alloy or made of DMC.
3.4 Contactor is a flat structure arrangement, the left part is contact system, the right part is electromagnetic system. From: Home of Electrical Technology
3.5 Contact system is composed of dynamic and static contacts and vacuum interrupter, which is installed in the base made of insulating material.
3.6 The vacuum interrupter chamber adopts new contact material to seal the row at one time, and the electromagnetic system adopts DC double coil.

4. Advantages of vacuum contactor
AC vacuum contactor has strong ability to extinguish the isolation, good voltage resistance, high operating frequency, long life, no arc external spray, small size, light weight and long maintenance cycle.
Vacuum contactor vacuum interrupter manufacturing process is very demanding, if the process is not good, the vacuum of the interrupter is easy to decline.
Contact material material is not good, in the breaking current will appear “cut-off overvoltage” phenomenon, that is, in the breaking current, due to the vacuum interrupter arc extinguishing ability is very strong, the arc current is not natural over zero when cut off, but from a certain value of the current suddenly drop to zero, resulting in a high overvoltage.
The interrupting voltage can endanger the safe operation of electrical equipment.

Click: Vacuum contactor