We can also call it a resistance type. Most of them achieve temperature measure by the method of sensing temperature by resistance. Often platinum wires, thermistors, copper wires, and tungsten wires are used as the temperature measuring resistance of the equipment, but this type of resistance has its own advantages and disadvantages. Generally, electronic temperature controllers use thermistor-type sensors in household air conditioners, which are also suitable for the control of floor heating system.
Its working principle is mainly based on the physical phenomenon of thermal expansion and contraction. First of all, this phenomenon is basically common to objects, but the structure of different objects is not the same, so its thermal expansion and contraction are different. The degree is also different.
The bimetallic strip of this type of temperature controller uses conductors of different materials on both sides, which force the metal strip to bend to different degrees when temperature changes. When it touches a set contact or switch, it will make the set circuit (protection) starts to work.
In fact, this type of temperature controller is also developed on the basis of bimetallic strip. It can mainly play a role in overheating protection of various electric heating equipment. It is generally used in series with thermal cut-off, and the sudden jump temperature controller is used as the primary protection.
Among them, the thermal cut-off acts as a secondary protection when the equipment fails, causing the electrical heating element to exceed the limit temperature, so it can effectively prevent the burning of the electrical heating element from causing unnecessary accidents.
Its working principle is to realize the monitoring function by the way that some paints produce different colors at different temperatures. For example, the liquid crystal will appear in different colors at different temperatures, and then use colors such as those of cameras and data provided by the collector for the circuit to realize the control of the circuit.
Through the principle of thermal expansion and contraction of the temperature-sensitive fluid and the inability of the liquid to be compressed, automatic control and adjustment are realized. In the process of temperature increase, the temperature-sensitive liquid will gradually expand, and the generated driving force will lead the heat medium to be reduced, and the output temperature is therefore reduced.
When the temperature of this type of temperature controller decreases, the temperature-sensitive liquid changes to a gradual contraction state. Under the action of the reset device, the heat medium will be increased, and the output temperature will increase again, so that the controlled temperature can reach and maintain within the set range.