Precautions for detecting thermistor of induction cooker with multimeter

When using a multimeter to detect the thermistor of an induction cooker, you should pay attention to the following:
1) The nominal resistance value of the thermistor refers to the resistance value when the ambient temperature is 25℃, so when measuring the resistance value of the thermistor, you need Pay attention to the influence of ambient temperature on its resistance value. When the ambient temperature is 25℃, the resistance value of the thermistor measured is its nominal resistance value. If the ambient temperature is not 25 ℃, it is a normal phenomenon that the measured resistance value does not match the nominal resistance value of the thermistor.
2) If you need to detect whether the thermistor has a positive temperature coefficient or a negative temperature coefficient, you can heat the surrounding of the thermistor when detecting the thermistor (such as using an electric soldering iron close to the thermistor). When the resistance value increases, it is a PTC thermistor. On the contrary, it is NTC thermistor.
3) When testing the PTC thermistor, the thermistor should be disconnected from the circuit to cut off the PTC heat The path between the sensitive resistor and the degaussing coil. In addition, when testing at room temperature, it should not be tested immediately after the power is turned off or after welding, because the temperature of the PTC thermistor is high at this time, and the measured resistance value will be obviously If it is greater than the nominal value, it is easy to cause misjudgment. The test should be performed when the temperature of the PTC thermistor is naturally cooled down to room temperature.
4) NTC thermistor is highly sensitive to temperature, so it is not suitable to use a multimeter to measure its resistance. This is because the working current of the multimeter is relatively large, and when it flows through the thermistor, it will generate heat and change the resistance value. But for beginners, it is only necessary to roughly test whether the thermistor can work, so it is also possible to use a multimeter to detect it.