When the coil is energized, the coil current will generate a magnetic field and generate enough electromagnetic suction to overcome the reaction force, so that the static core will generate electromagnetic suction to attract the moving core, and the moving core will push the moving contact until it contacts the static contact, so that the contact is connected. When the coil voltage disappears or the coil voltage decreases to a certain value, which is called the release voltage, the moving core is released by the return spring, and the contact will then be separated.