how does a resistance temperature sensor work?

Resistance temperature sensor is mainly sensor-like thermometer that uses the characteristics of conductor or semiconductor resistance values to measure temperature according to the principle of resistance value changing with temperature. Resistive temperature sensors are susceptible to some factors when measuring, which affects the accuracy of their detection, so when using resistive temperature sensors, we should exclude these possible interference factors. Next, I will introduce how to use the resistive temperature sensor.

How are resistive temperature sensors used?

1. The measured resistance value must pass the current, but the current will make the resistance heat and increase the resistance value.

In order to avoid excessive error caused by this factor, a small current should be passed through the resistor as much as possible. Of course, the current is too small to make the voltage drop across the resistor too small, which makes accurate measurement difficult.

It is generally believed that the current through the resistor should not exceed 6mA, because this is only 14mw for the resistance value of Pt100 thermal resistance at 850°C of 390 ohms, which will not cause significant errors.

2. When the resistance is measured by the bridge method, the output diagonal of the bridge has a common-mode voltage.

If the negative terminal of the power supply of the bridge is used as the ground wire, the two output wires of the bridge have working voltages to ground, and the differential mode operating voltage between the two wires reflects the degree of imbalance. This puts forward certain requirements for the design of electronic circuits, or there are requirements for docking points.

3. When measuring resistance with potentiometer, if multiple thermal resistors share a constant current source, there is also a common-mode voltage.

Multiple thermal resistors are connected by a four-wire method, and the current lines can be connected in series, powered by the same constant current source, and the two working voltage lines connected to the potentiometer are switched to each thermal resistance respectively, and multi-point patrol detection can be performed. However, there is a common-mode voltage on its two working voltage lines, and the value of the common-mode voltage is not equal, if it is connected to the computer interface, we must pay attention to this feature.

Different measurement points are measured with thermal resistance, and the index number can be the same or different. It is powered by the same constant current source, and the current is all I. The two working voltage lines of each pole are converted by multiple switches according to the A / D conversion part of the computer, and ordinary integrated multiswitches can be used here, but be sure to switch two lines each time. According to the solid connection method, the common-mode voltage increases successively.

4. The thermal resistance of the same index number can measure the average temperature of multiple points in series.

With the two-wire connection method, the greater the number of thermal resistance in series, the greater the total RO. The thermal resistance is not easy to encounter parallel connection, and it has no practical significance.

How are resistive temperature sensors used? Seeing this, you must also know more about resistive temperature sensors! As a new and practical temperature sensor, the application scenarios of resistive temperature sensors are gradually increasing. The growing market demand has driven the further development of resistive temperature sensors. In the future, I believe that the stability and practicality of resistive temperature sensors will be greatly improved!

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