Thermistor is a sensitive element. According to the difference of temperature coefficient, it can be divided into positive temperature coefficient thermistor (PTC) and negative temperature coefficient (NTC). The typical feature of thermistor is that it is sensitive to temperature and shows different resistance values at different temperatures.
The higher the temperature, the higher the PTC resistance and the lower the negative temperature coefficient resistance. They are all semiconductor devices.
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Thermistor does not work for a long time. When the ambient temperature and current are in zone C, the heat dissipation power of the thermistor is close to the heating power, so it may or may not work. When the ambient temperature is the same, the action time of thermistor decreases sharply with the increase of current. When the ambient temperature is high, the action time of thermistor is short, and the holding current and action current are small.
1, PTC effect is a material with positive temperature coefficient effect (PTC), which only means that the resistance of the material increases with the increase of temperature. For example, most metal materials have PTC effect. In these materials, PTC effect shows that the resistance increases linearly with the increase of temperature, that is, linear PTC effect.
2. When the nonlinear PTC effect undergoes phase transition, the resistance of the material will increase by several orders of magnitude to more than ten orders of magnitude in a narrow temperature range, that is, the nonlinear PTC effect. Many conductive polymers will show this effect, such as polymer PTC thermistor, which is very useful for manufacturing overcurrent protection devices.
3. The polymer PTC thermistor used for overcurrent protection is usually called self-recovery fuse (hereinafter referred to as thermistor). Because of its unique positive temperature coefficient resistance characteristics, it is very suitable for over-current protection devices. Like ordinary fuses, thermistors are used in series in the circuit.
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