Thermistor working principle, detection method

It can be said that a thermistor is a type of thermal resistance.

Therefore, the principle is that temperature causes a change in resistance.

But now RTDs are generally industrialized, basically referring to PT100, CU50 and other commonly used RTDs.

The difference between the two is that general thermal resistance refers to metal thermal resistance (PT100), etc., and thermistor refers to semiconductor thermal resistance.

Since the temperature coefficient of semiconductor RTD is more than 10 100 times larger than that of metal, a temperature change of 10-6 can be detected, and the resistance value can be arbitrarily selected. That's why it's called a thermistor.

However, the temperature resistance of the thermistor is nonlinear, and the linearity of each model is different, and the temperature measurement range is relatively small. Therefore, the industry generally uses metal thermal resistance, which is what we usually call thermal resistance.

Thermistors, on the other hand, are generally used in circuit boards, such as a fuse, as you said. Due to its large resistance value changes with temperature, it can be used as a protector. Of course, this is only one aspect, and it has many uses, such as the cold junction temperature compensation of thermocouples is compensated by thermistors.

In addition, due to the nonlinear relationship between the resistance value and temperature... So the consistency of the components is very poor, and it does not have a standard signal like RTD.

1. The thermistor has the characteristic of changing the resistance value with the change of temperature.

2. By measuring the resistance of the thermistor, the temperature can be measured.

Strictly speaking, almost all conductors and semiconductor materials have their own resistivity that changes under the influence of temperature! The most common of the various temperature sensing elements that take advantage of this characteristic is the thermistor!

The characteristic of thermistors is that their resistance changes with temperature! We convert this change in resistance into a change in current! It is displayed by the pointer or number after circuit processing! This completes the temperature measurement!

The main features of thermistors are:

1. The sensitivity is high, and the temperature coefficient of resistance is more than 10 100 times greater than that of metal, and it can detect 10-6 temperature changes;

2. The working temperature range is wide, the normal temperature device is suitable for -55 315, the applicable temperature of the high temperature device is higher than 315 (the current maximum can reach 2000), and the low temperature device is suitable for -273 -55;

3. Small size, able to measure the temperature of voids, cavities and blood vessels in organisms that cannot be measured by other thermometers;

4. Easy to use, the resistance value can be arbitrarily selected;

5. Easy to process into complex shapes, can be produced in large quantities;

6. Good stability and strong overload capacity.

How it works:

1. The thermistor will be in an inactive state for a long time; When the ambient temperature and current are in the C region, the heat dissipation power of the thermistor is close to the heat generating power, so it may or may not operate.

2. When the ambient temperature of the thermistor is the same, the action time is sharply shortened with the increase of current; Thermistors have shorter operating times and smaller maintenance and operating currents at relatively high ambient temperatures.

Function: 1. Temperature measurement. As a thermistor sensor for measuring temperature, the structure is generally simple and cheap;

2. Temperature compensation. Thermistor sensors can compensate for the humidity of certain components within a certain temperature range;

3. Overheating protection. When the temperature is greater than the abrupt change point, the current in the circuit can be abruptly changed from a few tenths of a milliampere to tens of milliamps, so the relay acts, so as to achieve overheating protection.

The thermistor temperature measurement of the original brigade is based on their ().

a.Voltammetry characteristics.

b.Thermoelectric properties.

c.Nominal resistance values are noisy.

d.Measure the bending rate of power demolition.

Correct answer: B

The thermistor is the resistance value that changes with temperature, and the detection method is to directly measure its resistance.