Application of thermistor in daily life (I)

According to different temperature coefficients, thermistor can be divided into two types: positive temperature coefficient thermistor (PTC thermistor) and negative temperature coefficient thermistor (NTC thermistor). Thermistor has been widely used for temperature control, temperature detection and temperature compensation of household electric appliances. 

1.Liquid level control 

Put two NTC thermistors on safe places of vessel height and low liquid level, and apply thermal current. The surface temperature immersed in the liquid at the bottom has the same temperature with ambient temperature. When resistance on high is submerged in the liquid level, surface spill will decline and the resistance will increase. Through observing the change of resistance and then informing alarm device, the action circuit will cut off the liquid pipe lineandplay the role of liquid level protection. When the liquid level drops, the thermistor at the bottom will come out gradually. At the same time, with the increase of surface temperature, the resistance will decline. Through judging the available change of resistance and in time informing alarm device, the action circuit will open the feed tube to supply liquid. 

2.Temperature control

As a thermistor used for measuring temperature with simple structure and low cost, because of its high resistance, the contact resistance at the junction can be omitted and it can be used in the remote telemetry.

3.Temperature compensation

Using the negative temperature characteristics, it can play a role of compensation in electric devices. When overload results in current and temperature increasing, the resistance of thermistor will become larger to make the current reduce, so that it plays the role of compensation and protection. At this point, it is noteworthy that the thermistor should be connected in the electronic circuit in series.