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Working principle of power type thermistor

Mar. 09, 2021

The conductivity of the NTC thermistor increases with the increase of temperature, while the resistance of the NTC thermistor decreases with the increase of temperature.

Working principle of power type thermistor

According to the characteristics and properties of power NTC thermistor, its working process shows as bellow:

The R25 is in series of circuit nodes which are prone to produce large current power on (large current influx)large resistance value (R25 value) block( suppress big I ) The body of R25 has a sudden heat, T↑→ absorb energy; big I disappears, continuous current R25 value decreases steady currentR25 decreases to small valuesteady state ( balance point ) Now I= rated current, RR25 value

Working principle of power type thermistor

From the above working process, we can clearly see that the working process of power NTC resistor is the process of converting current into heat energy by absorbing heat. The power NTC thermistor has such a significant thermal effect that it can effectively suppress the power-on surge current through its own zero-power resistance value, and after the suppression of the inrush current, due to the continuous action of the current (steady-state current) through it, its own resistance value (residual resistance value) has been reduced to a very small degree. Its power consumption has been negligible, and will not affect the normal working current. Therefore, it is widely used to suppress the surge current of electronic equipment.

Working principle of power type thermistor

According to Joule's law, the energy absorbed by the thermistor when working is Q=I2·R·T (Joule: J).


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