What are the principles and connections of 380V AC contactors?

When the coil is energized, the static iron core generates electromagnetic attraction to attract the moving iron core. Because the contact system is linked with the moving iron core, the moving iron core drives the three moving contacts to act at the same time, the main contact is closed, the auxiliary normally closed contact mechanically connected with the main contact is disconnected, and the auxiliary normally open contact is closed, thus turning on the power supply. When the coil is powered off, the suction disappears, and the linkage part of the moving iron core is separated by the reaction force of the spring, so that the main contact is disconnected, the auxiliary normally closed contact mechanically connected with the main contact is closed, and the auxiliary normally open contact is disconnected, thereby cutting off the power supply.

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The innovative technical feature of permanent magnet AC contactor is to replace the traditional electromagnet drive mechanism with permanent magnet drive mechanism, that is, the control device composed of permanent magnet and microelectronic module replaces the electromagnetic device in traditional products, and there is no working current in operation, only a weak signal current (0.8- 1.5mA). Microelectronics module consists of six basic parts: 1. Power supply rectification; 2. Control the real-time detection of power supply voltage; 3. Release energy storage (some also have pull-in energy storage, but not necessarily); 4. Energy storage capacitor voltage detection; 5. Anti-interference threshold voltage detection; 6. Release the logic circuit. These six parts are necessary parts of the electronic control part of the permanent magnet operating mechanism. If any part is missing, the operating mechanism will not work normally in some cases. These six parts also determine that the operating mechanism can have anti-sloshing function.

(1) energy saving:

The closing maintenance of traditional contactor is realized by overcoming the opening spring by the electromagnetic force generated by the closing coil. Once the generated electromagnetic force is insufficient to overcome the reaction force of the spring, the contactor cannot remain closed. Therefore, the traditional AC contactor closing maintenance must be maintained by the continuous energization of the coil, and the current varies from tens of milliamps to thousands of milliamps. The permanent magnet AC contactor relies on the permanent magnet force, which does not need the coil to generate electromagnetic force through current, and only has the working current of 0.8 Ma- 1.5 Ma of the electronic module, so it can save electricity to the maximum extent, and the power saving rate is as high as 99.8%.

②. No noise:

The traditional AC contactor closes the silicon steel sheet by energizing the coil, so that the static and dynamic silicon steel sheets attract each other. When the power grid voltage is insufficient or the surface of dynamic and static silicon steel sheets is uneven or there are dust and foreign objects, noise will be generated. The closure of permanent magnet AC contactor is maintained by permanent magnet force, so there will be no noise.

③. No temperature rise:

Traditional contactors rely on coils to generate enough electromagnetic force to maintain attractive force. The coil is composed of resistance and inductance, and it will inevitably heat up if the current is applied for a long time. On the other hand, the magnetic flux in the iron core will also generate heat. These two kinds of heat work together in the contactor cavity, which often burns out the contactor coil and reduces the capacity of the main contact. Permanent magnet AC contactor is maintained by permanent magnet force. Without the maintenance coil, there is naturally no temperature rise.

(4). Contact fatigue:

The attraction of traditional AC contactor is realized by energizing the coil, and the attraction is related to current and magnetic gap. When the voltage fluctuates in the critical state of closing and opening, the contactor is in the state of sharing and closing, which will constantly vibrate, resulting in contact welding or burning, and motor burning out. However, the attraction of permanent magnet AC contactor is completely realized by permanent magnet force, and the attraction is completed at one time, so the voltage fluctuation will not affect the permanent magnet force, and the main contact will not be burned due to vibration, so the possibility of burning the motor is greatly reduced.

⑤ Long service life and high reliability;

The life and reliability of contactor are mainly determined by the life of coil and contact. The traditional AC contactor will generate heat when it works, especially when the voltage, current and magnetic gap increase, which will easily lead to heat and burn the coil, while the permanent magnet AC contactor does not have the possibility of burning the coil. Contact ablation is mainly caused by arc generated during opening and closing. Compared with the traditional contactor, the permanent magnet AC contactor not only has the same electromagnetic force, but also has permanent magnetic force, so the closing speed is much faster than the traditional AC contactor. According to the test, the closing time of permanent magnet AC contactor is generally less than 20ms, while the closing speed of traditional contactor is generally about 60 ms. When opening the brake, permanent magnet AC contactor not only has the function of opening spring, but also has the function of magnetic pole repulsion, which makes the opening speed much faster than that of traditional contactor. According to the test, the opening time of permanent magnet AC contactor is generally less than 25ms, while the opening speed of traditional contactor is generally more than 80 ms In addition, the heating of coil and iron core will reduce the capacity of main contact, and insufficient suction or vibration caused by voltage fluctuation will make the main contact of traditional contactor heat, arc and even weld. Compared with the traditional AC contactor, under the same conditions, the contact life of permanent magnet AC contactor is prolonged by 3-5 times.

6. Anti-electromagnetic interference:

The permanent magnetic circuit used in permanent magnet AC contactor is completely sealed and will not be disturbed by external electromagnetic interference during use.

7. Intelligent anti-sloshing:

The control electronic module controls the set release voltage value, and can send out reverse pulse current after a certain delay, so as to realize low-voltage delayed release or power-off delayed release, prevent the motor controlled by it from jumping and stopping due to grid voltage fluctuation (power flicker), and maintain the stability of the production system. In particular, enterprises with continuous plant production can reduce the consumption of electricity, steam and natural gas, and reduce labor costs, equipment damage and repair costs.