The contact above the AC contactor contact is made of silver alloy. Contact system: Contact is the executive part of contactor, including main contact and auxiliary contact. The main contact is used to connect and disconnect the main circuit and control the larger current. The auxiliary contact is in the control circuit to meet the requirements of various control modes. Contact system maintenance: 1. Check whether the positions of moving and static contacts are aligned and whether the three phases are closed at the same time. If there is any problem, adjust the contact spring; 2. Check the degree of contact wear, the wear depth shall not exceed 1mm, the contact is burnt, and it shall be replaced in time when welding falls off; When slightly burned, it generally does not affect the use. Sandpaper is not allowed to be used when cleaning contacts, and plastic files should be used; 3. Measure the interphase insulation resistance, and the resistance shall not be less than10mΩ; ; 4. Check whether the auxiliary contact is flexible, and the contact stroke should meet the specified value. Check whether the contact is loose or falling off. If problems are found, repair or replace them in time.