Working principle
When the contactor coil is energized, the coil current will generate a magnetic field, which makes the static iron core generate electromagnetic suction to attract the iron core, and drives the point action of the AC contactor. Normally closed contact is disconnected, normally open contact is closed, and the two are linked.When the coil is power off, the electromagnetic suction disappears, the armature is released under the action of the release spring, so that the contact recovers, the normally open contact is disconnected, and the normally closed contact is closed.The principle of a DC contactor is somewhat similar to that of a temperature switch.
Main structure
AC contactor uses the main contact to control the circuit and the auxiliary contact to conduct the control loop.The main contact is generally normally open contact, and the auxiliary contact often has two pairs of normally open contact and normally closed contact, small contactor is often used as an intermediate relay with the main circuit.The contacts of the AC contactor are made of a silver-tungsten alloy with good electrical conductivity and high temperature ablation resistance.The power of AC contactor action comes from the magnetic field generated by AC through the coil with an iron core. The electromagnetic core is made of two "mountain" shaped young silicon steel sheets, one of which is fixed and equipped with a coil. The working voltage can be selected from a variety of options.In order to stabilize the magnetic force, a short circuit ring is added to the pulling surface of the iron core.AC contactor in the loss of power, rely on the spring reset.The other half is a movable core, constructed in the same way as a fixed core, to open and close the primary and auxiliary contacts.The contactor above 20A is equipped with an arc extinguishing cover, which can quickly break the arc and protect the contact point by using the electromagnetic force generated when the circuit is disconnected.The contactor can operate at a high frequency, up to 1200 times per hour for power on and off control.The service life of contactors is very high, the mechanical life is usually millions to 10 million times, and the electrical life is generally hundreds of thousands to millions of times.
Technology development
AC contactor is made as a whole, the appearance and performance are also improving, but the function remains the same.No matter how advanced the technology is, the common AC contactor still has its important position.Air type electromagnetic Contactor: It is mainly composed of contact system, electromagnetic operation system, bracket, auxiliary contact and shell (or chassis).Because the coil of the AC electromagnetic contactor is generally powered by the AC power supply, after the contactor is excited, there will usually be a high decibel "Luo" noise, which is also the feature of the electromagnetic contactor.After the 80's, the countries study AC contactor electromagnet silent and power saving, one of the basic feasible solutions is the AC power supply with transformer after step-down, and then the internal rectifier into the DC power supply after the power supply, but this complex control mode is not seen.Vacuum contactor: Vacuum contactor is the contact system with a vacuum degaussing chamber contactor.Semiconductor contactor: a semiconductor contactor is a contactor that performs current operation by changing the on-state and off-state of a circuit circuit.Permanent magnet contactor: permanent magnet AC contactor is a micro power consumption contactor formed by replacing the traditional electromagnet drive mechanism with permanent magnet drive mechanism by using the principle of similar repulsion and opposite attraction of magnetic poles.
