The core of the 3MP+PTC self-supporting protector is composed of a pre-calibrated snap-type bimetallic disc, which is welded to the metal shell and integrally formed with the terminals. The shell is covered with a plate, and a resistance heating wire is welded on the board to improve the current sensitivity of the device. The PTC sheet is installed on the top of the metal shell with clips to meet the self-sustaining requirements. Various standard terminal connection configurations and selected materials make the product easy to operate and install. The terminal connection configuration can be customized according to user needs. Wires with connectors can be easily connected with standard crimp terminals. Various standard wire configurations can be provided, and users can customize according to their needs.
The working principle of the 3MP+PTC self-supporting device is simple and effective. The action of the protector depends on the current passing through the protector and the temperature of the surrounding environment. When the disc reaches a preset temperature, the circuit is cut off. Due to the self-constant temperature heating of the PTC disc, the temperature of the bimetal disc will not drop to the closing temperature. The contact will remain open until the user turns off the device, thus ensuring higher safety. After the device is turned off, the temperature of the entire device drops to a safe value, and the contact automatically resets. Bimetal discs are very sensitive to temperature and current under overload conditions. In the case of a locked rotor, the combination of the resistance heating wire and the bimetal disc can provide an extremely accurate trip time and play a maximum protective effect.