The temperature switches is a switch that determines the on-off based on the temperature of the object to be controlled. According to their different action principles, they can be divided into bimetallic type, pressure type, and thermosensitive ferrite type.

Regarding the bimetallic temperature switches: Various metals have the characteristic of thermal expansion and cold contraction, and different metals have different coefficients of expansion with temperature changes. The bimetallic temperature switch operates based on this principle. The bimetallic sheet is composed of the upper layer of "high manganese alloy" and the lower layer of "invar steel". The expansion coefficient of the former is dozens of times that of the latter, respectively known as the "active layer" and "passive layer". At normal temperature, the contacts A and B of the copper sheet and spring sheet are connected, and the entire circuit is in a connected state. When the temperature rises, the active layer expands more than the passive layer, and the bimetallic sheet bends downwards. When the temperature reaches to a certain extent, the circuit disconnects. After cooling to a certain extent, the bimetal sheet recovers and the circuit is connected.

The TP series thermal protector is a type of thermal sensitive reaction component that uses a fixed temperature bimetallic plate. When the temperature of the main component of the product increases, the heat generated is transferred to the bimetallic plate. When the action temperature setting is reached, it quickly acts, and the contact is opened or closed through the action of the mechanism; When the temperature drops to the reset temperature setting, the bimetallic disc quickly returns to its original state, causing the contacts to close or open, to achieve the purpose of connecting or disconnecting the circuit, thereby controlling the circuit.