The operating principle of the contactor is: when the contactor coil is energized, the coil current will generate a magnetic field, and the generated magnetic field will make the static iron core attract the moving core with electromagnetic attraction, and drive the communication contactor point action, the normally closed contact is disconnected, and the normally open contact is closed, and the two are linked. When the coil is de-energized, the electromagnetic attraction disappears, and the armature is released under the action of the release tension spring, so that the contact is restored, the normally open contact is disconnected, and the normally closed contact is closed. The operating principle of a DC contactor is somewhat similar to that of a temperature switch.
AC contactors use the main contact to control the circuit and the auxiliary contact to turn on the control loop. The main contact is generally a normally open contact, and the auxiliary contact often has two pairs of normally open contact and normally closed contact, and the small contactor is often used as an intermediate relay 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 comes from the magnetic field generated by the communication through the coil with the core, and the electromagnet core is composed of two "mountain" shaped fine silicon steel sheets stacked together, between which a fixed iron core is sleeved with a coil, and the operating voltage can be selected in a variety of ways. In order to stabilize the magnetic force, a short-circuit ring is added to the suction surface of the core. After the power loss of the communication contactor, it is reset by the tension spring. The other half is the movable core, which is constructed in the same way as the fixed core, and is used to drive the closure and disconnection of the main contact and the auxiliary contact. Contactors above 20A are 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, up to 1200 times per hour when used as a power switch on and block control. The service life of the contactor is very high, with a mechanical life of millions to 10 million cycles, and an electrical life of hundreds of thousands to millions of times.
The shape and function of the AC contactor system as a whole are also constantly improving, but the function remains the same. No matter how far the skill is developed, the ordinary communication contactor still has its important place.
Air Electromagnetic Contactor (English: Magnetic Contactor): It is mainly composed of a contact system, an electromagnetic operation system, a bracket, an auxiliary contact and a shell (or chassis). Because the coil of the communication electromagnetic contactor is generally powered by the communication power supply, after the contactor is excited, there is generally a high decibel "cluck" noise, which is also the characteristic of the electromagnetic contactor. After the 80s, various countries discussed the silent and power-saving of communication contactor electromagnets, and one of the basic feasible plans was to reduce the voltage of the transformer for communication power supply, and then convert it into DC power supply through the internal rectifier and then supply power, but this messy control method is rare.
Vacuum contactor: Vacuum contactor is a contactor with a vacuum degaussing chamber for the contact system.
Semiconductor contactor: A semiconductor contactor is a contactor that accomplishes current operation by changing the conduction and open conditions of a circuit circuit.
Permanent magnet contactor: Permanent magnet communication contactor is a kind of micro-power contactor formed by using the principle of same-sex repulsion and opposite-sex attraction of magnetic poles, and replacing the traditional electromagnet drive mechanism with a permanent magnet drive mechanism.
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