Contactors are divided into AC contactors (voltage AC) and DC contactors (voltage DC), which are used in electric power, power distribution and power applications. In a broad sense, a contactor refers to an electrical appliance that uses a coil to flow current to generate a magnetic field and close the contact to control the load.

The working principle of the contactor is: when the contactor coil is energized, the coil current will generate a magnetic field. The generated magnetic field causes the static iron core to generate electromagnetic attraction to attract the moving iron core and drive the AC contactor point to act. The normally closed contact is disconnected. The normally open contact is closed, and the two are linked. When the coil is de-energized, the electromagnetic attraction force disappears, and the armature is released under the action of the release spring to restore the contact, the normally open contact is disconnected, and the normally closed contact is closed. The working principle of a DC contactor is somewhat similar to that of a temperature switch.

The AC contactor uses the main contact to control the circuit, and the auxiliary contact to conduct the control loop.

 

 

The main contact is generally a normally open contact, and the auxiliary contact often has two pairs of normally open contacts and a normally closed contact. Small contactors are often used as intermediate relays to cooperate with the main circuit.

The contacts of the AC contactor are made of silver-tungsten alloy, which has good electrical conductivity and high temperature ablation resistance.

The power of the AC contactor's action comes from the magnetic field generated by the AC passing through a coil with an iron core. The electromagnet core is composed of two "hill" shaped young silicon steel sheets. One of the fixed iron cores is covered with a coil. The working voltage can be varied. choose. In order to stabilize the magnetic force, a short-circuit ring is added to the suction surface of the iron core. After the AC contactor loses power, it relies on the spring to reset.

The other half is the movable iron core, the structure is the same as the fixed iron core, used to drive the main contact and auxiliary contact to close and open.

The contactor above 20A is equipped with an arc extinguishing cover, which uses the electromagnetic force generated when the circuit is disconnected to quickly break the arc and protect the contact.

The contactor can be operated at a high frequency. When used as a power switch on and off control, the maximum operating frequency can reach 1,200 times per hour.

The service life of the contactor is very high, the mechanical life is usually several million to 10 million times, and the electrical life is generally hundreds of thousands to several million times.

The AC contactor is made as a whole, and its appearance and performance are constantly improving, but the function is always the same. No matter how advanced the technology is, ordinary AC contactors still have an important position.

 

Air-type electromagnetic contactor (English: Magnetic Contactor): mainly composed of contact system, electromagnetic operating system, bracket, auxiliary contact and shell (or chassis).

Because the coil of the AC electromagnetic contactor is generally powered by AC power, after the contactor is excited, there will usually be a high-decibel "squeak" noise, which is also a characteristic of the electromagnetic contactor.

After the 1980s, various countries studied the noiselessness and power saving of AC contactor electromagnets. One of the basic feasible solutions is to reduce the voltage of the AC power supply with a transformer, and then transform it into a DC power supply through an internal rectifier to supply power. However, this complex control method does not Rarely.

Vacuum contactor: The vacuum contactor is a contactor that uses a vacuum degaussing chamber in the contact system.

Semiconductor contactor: The semiconductor contactor is a contactor that completes current operation by changing the on state and off state of the circuit loop.

Permanent magnetic contactor: The permanent magnetic AC contactor is a kind of micro-power contactor formed by using the principle of magnetic poles to repel and attract each other, and replace the traditional electromagnet drive mechanism with a permanent magnet drive mechanism.