Requirements for materials of motor platinum resistors

The current motor platinum resistors can be divided into metal thermal resistors and semiconductor thermal resistors (i.e. thermistors) according to the materials. Among them, metal thermal resistors are mainly platinum and copper. Common models of thermal resistors in industry include Pt100, Pt10, Cu50, Cu100, etc. Among them, due to the performance of Pt100, this type of thermal resistor has become a common thermal resistor in industry. The characteristics of motor platinum resistors are high accuracy, good stability and reliable performance. In an oxidizing atmosphere, even at high temperatures, its physical and chemical properties are very stable. Therefore, it is set as a reference thermometer within a certain temperature range. However, platinum resistors are easily contaminated by reducing gases in a reducing atmosphere, especially at high temperatures, causing the platinum wire to become brittle and changing the original correspondence between resistance and temperature. In this case, the resistor must be isolated from harmful gases by a protective sleeve. Motor platinum resistors have the following requirements for manufacturing materials:
1. The temperature coefficient of resistance should be large. The temperature coefficient of resistance is defined as the relative change in resistance for every 1 Kelvin increase in temperature. The larger the temperature coefficient of resistance, the higher the sensitivity of the thermometer and the more accurate the measurement result.
2. Larger resistivity. The larger the resistivity, the smaller the volume of the thermal resistor, the smaller the heat capacity and thermal inertia, and the faster the response to temperature changes.

3. Within the temperature measurement range, the chemical and physical properties are stable.

4. The relationship between resistance value and temperature is approximately linear.

5. Good reproducibility.

With the miniaturization of electronic products, the temperature transmitter of the motor platinum resistance series, which was originally used as a DC 4-20mA or 1-5V standard signal transmission, has also been miniaturized. It can be installed in the thermocouple junction box on site and integrated with the thermocouple, and only two ordinary wires are needed for connection without using more expensive compensation wires. Thermocouples with converters and displays that integrate detection, signal conversion and display can meet the needs of on-site display.