The principle of low-voltage AC contactor

AC contactor is widely used as a power breaking and control circuits. It uses the main contact to open and close the circuit, with auxiliary contacts to execute control commands. Generally only the main contacts normally open contacts, and often two pairs of auxiliary contacts with normally open and normally closed contacts function, small contacts are often used as intermediate relay with the main circuit. Please visit: transmission and distribution equipment web browser for more information  mcb circuit breaker  contacts made from silver tungsten alloy with good electrical conductivity and high temperature ablative. AC contactor has four main components: (1) electromagnetic systems, including attracting coil, moving core and static core; (2) contact system, including the three main contacts and two normally open and two normally closed auxiliary contacts, which are linked and mutually movable core linkage; (3) interrupter device, usually a larger capacity AC contactor has interrupter device, in order to quickly cut off the arc, from burned main contacts head; (4) insulated housings and accessories, all kinds of springs, transmission, short-circuit ring, terminal and so on. How it works: When the coil is energized, the static core generates electromagnetic suction will pull the movable core, because the contact system is moving core linkage, so moving core driven by three movable contacts to run simultaneously, contact closure, thereby turning on the power. When the coil is de-energized, the suction disappears, moving core linkage relies in part on the spring reaction force separation of the main contacts disconnect the power off. AC contactor choice: (a) continuous operation of the device. Contactors count by 67-75%, ie, 100A, AC contactor, can only control the maximum rated current is 67-75A following equipment. (2) intermittent operation of the device. Contactors count by 80%, ie, 100A, AC contactor, can only control the maximum rated current is 80A following equipment. Source: transmission and distribution equipment net (3) repeated short-time working equipment. Contactors count by 116-120%. Namely 100A, AC contactor, can only control the maximum rated current is 116-120A following equipment. Also consider the work environment and the contactor structure. Also noted is: As the market competition, some domestic manufacturers to reduce costs, has cut corners, such as: the production of reduced diameter of the coil  Air circuit breaker even less in contact with the material or do not meet the national standard thickness and cross-section are not enough. This situation is not only reflected in other products such as short circuit is also true. Resulting in actual use, the subject of the contact 100A or short circuit, only the actual load 80A or less, the failure rate is high. So now there is a popular saying: with domestic
 low-end products, to illustrate its nameplate rated capacity hit 7 fold use! One: general three-phase contactor a total of eight points, three inputs, three outputs, but also There are two control points. Is the corresponding output and input, it is easy to see it. If you want to add self-locking, then you also need a point from the output terminal of the cable to the control point above. Two: First, should know the principles of AC contactor. He came to Canada with the external power supply to the coil, generate electromagnetic fields. Power pull, disconnect the power after the contact point. Understand the principle, you should find out additional power contacts, that is, the two coil contacts, generally the lower portion of the contactor, and each on one side. Several other inputs and outputs generally in the upper part to see that. Also note how much external power supply voltage (220V or 380V), are generally marked must have. Also note that the point of contact is normally closed or normally open. If you have self-locking control, according to the principle haircut lines on it

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