The temperature detector P operates independent from any current supply. Temperature detection is recognized through a bimetal disk that has been specified in accordance with the required cut-off temperature TA. When this fixed cut-off temperature TA is reached, this bimetal disk will snap over, breaking a contact system and thereby interrupting the electric circuit of the device to be protected.
After cooling down and reaching the closing temperature TE, the bimetal disk will automatically return to its original position and thus close the contact. The electric circuit is closed again.