The modular contactor has a large carrying current, generally an internal pull-in coil to control its action, and the control coil is operated by various types of relays connected in series with it. After the thunder, it will trip because the relay of the modular contactor has overcurrent or grounding protection function. When there is lightning on the line, it will control the action of the modular contactor, cut off the load power supply, and protect the equipment from high voltage. High current damage or grounding poses a safety hazard.
modular contactors are widely used as power breaking and control circuits. The modular contactor uses the main contact to open and close the circuit, and the auxiliary contact to execute the control command. The main contacts generally have only normally open contacts, while the auxiliary contacts often have two pairs of contacts with normally open and normally closed functions. Small contactors are often used as intermediate relays in conjunction with the main circuit. Thus, it functions as a remote control or a weak control of strong powerThe contact of the modular contactor is made of silver tungsten alloy, which has good electrical conductivity and high temperature ablation. The modular contactor is divided into a permanent magnet type modular contactor and an electromagnetic modular contactor.
The driving force of the modular contactor is derived from the AC electromagnet. The electromagnet is composed of two "mountain" shaped young silicon steel sheets, one of which is fixed, and the coil is placed on it, and the working voltage is variously available. In order to stabilize the magnetic force, the suction surface of the iron core is added with a short-circuit ring. The modular contactor relies on a spring to reset after power loss. The other half is a movable iron core, which is constructed like a fixed iron core to drive the opening and closing of the mainThe permanent magnet contactor is a new type of micro power contactor formed by replacing the conventional electromagnetic drive mechanism with a permanent drive mechanism. The working principle is to use the principle of the same polarity of the magnetic pole and the attraction of the opposite sex. Because the polarity of the permanent magnet mounted on the contactor linkage mechanism is fixed, and the soft iron fixed on the contactor base is under the action of the external control signal, the electronic module solidified together generates ten to twenty The positive and negative pulse currents of a few milliseconds cause the soft iron to have different polarities, so that the main contacts of the contactor can be attracted, held and released.
The structure of the electromagnetic modular contactor is mainly composed of an electromagnetic system, a contact system, an arc extinguishing system and other parts.
1. Electromagnetic system: The electromagnetic system consists of an electromagnetic coil and a core. It is an important part of the contactor and relies on it to drive the closure and disconnection of the contacts.
2. Contact system: The contact is the actuator part of the contactor, including the main contact and the auxiliary contact. The main contact functions to switch the main circuit on and off, controlling a large current, and the auxiliary contact is in the control loop to meet various control methods.
3. Arc extinguishing system: The arc extinguishing device is used to ensure that the arc generated when the contact is disconnected is reliably extinguished, and the damage of the arc to the contact is reduced. In order to quickly extinguish the arc at the time of disconnection, the contactor is usually equipped with an arc extinguishing device, generally adopting a semi-sealed longitudinal seam ceramic arc extinguishing cover and a strong magnetic blowing circuit.
4. Other parts: Insulated casing, spring, short-circuit ring, transmission mechanism, etc.
Advantages of permanent magnet contactors: 1. Good reliability and no interference from grid voltage. 2. The action speed is fast, 0.12-0.15s, and the traditional is 0.35-0.38s. 3. Quiet operation, no AC noise, no dust or oil pollution. 4. The module has no temperature rise, and it is resistant to aging, corrosion resistance and long service life is three times the traditional. 5. Maintenance-free, ultra-energy-saving and environmentally friendly, with a power saving rate of 99%.