Major Measures to Improve the Life of Low Voltage Magnetic Contactors

    Magnetic Contactor is an important component of low voltage electrical apparatus. Its life is one of the main indexes of quality evaluation. Therefore, it is very important to take some measures to improve its life. Here are the main measures to improve the life of contactors.

    Reasonable combination of suction characteristics and reaction characteristics can improve the life of contactor. The operating voltage of the contactor ranges from 85% to 110% n.

    When the contacts are closed and the iron core is sucked, the first and second runs of the contacts may lead to welding and increase the electric erosion of the contacts. In order to reduce the runout time of contacts, the mass and movement speed of contacts should be appropriately reduced, and the initial contact force of contacts should be appropriately increased. In order to reduce and prevent the second bounce of contacts (which is more harmful due to the large starting current), in addition to the good combination of suction characteristics and reaction characteristics to reduce collision energy, it is necessary to install buffer devices to the electromagnetic system to absorb kinetic energy such as armature.

    For the rotating structure, changing the lever ratio between armature arm and contact arm properly can change the contact pressure and closing speed of the contact, thus improving the contact bounce.

    The demagnetizing ring of AC core is a weak link in mechanism. When the armature collides with the core, the stress at the root and corner of the outer part of the core is the greatest, and it is easy to break. At present, the commonly used technology is to insert the dividing ring into the groove at the magnetic extreme part of the stationary core, and adhere it around with adhesive to increase the mechanical strength.

    In order to improve the mechanical life of the magnetic contactor, the area of the polar surface can be increased appropriately to reduce the impact stress. The polar surface of AC core and the angular part of DC core can also be hardened to prolong service life. It is very effective to reduce friction coefficient and improve wear resistance to choose reasonable motion pairs for rotating parts, such as Plastics-plastics or plastics-metals with small friction coefficient and strong wear resistance, or to add a small amount of molybdenum disulfide or graphite to heat-reversible plastics to make bearings or guideways.

    Selection of magnetic contactors

    When choosing contactor, the current level of contactor should be selected according to whether the work of the load under control is light task, general task or heavy task, power and operation of motor or other load, etc. The coil parameters of the contactor are selected according to the power supply of the control circuit, and the products of general or special specifications are selected according to the use environment.