Pt100 Platinum Resistance: Temperature Measurement Principle and Selection Attention of Platinum Resistance for Laboratory Use

　　pt100 platinum resistance:Air conditioning laboratory usually has a lot of temperature measurement points, high-precision measuring points are often used platinum resistance. We all know that the resistance value is related to the material, length, and cross-sectional area. Of course, temperature is also an indispensable factor. The thermometer that uses the resistance change caused by the temperature change to measure the temperature is called the hot platinum resistance. The thermometer has simple structure, convenient use, stable performance, high measurement accuracy and sensitivity, and is convenient for remote signal transmission, automatic recording and centralized control. It is usually suitable for temperature measurement between -200 and 500 °.
Platinum resistance and thermocouple have similar names, but the two temperature measuring devices are essentially different: 1. With the change of temperature, platinum resistance changes its resistance value, while thermocouple generates induced voltage changes; 2. Thermal resistance is a single metal/semiconductor material, and thermocouple is a bimetal/semiconductor material; 3. Different measurement temperature ranges: In comparison, thermal resistance is suitable for low temperature measurement, while thermocouple is suitable for high temperature measurement; 4. Different connection methods: thermocouple has positive and negative poles, but thermal resistance does not.

　　platinum resistanceThe material has the following requirements: 1, the temperature coefficient of resistance to be large. The temperature coefficient of resistance is defined as the relative change in resistance when the temperature rises by 1 Kelvin. The greater the temperature coefficient of resistance, the higher the sensitivity of the thermometer and the more accurate the measurement result. 2, large resistivity. The larger the resistivity, the smaller the thermal resistance volume, the smaller the heat capacity and thermal inertia, and the faster the response to temperature changes. 3. Stable chemical and physical properties within the temperature measurement range. 4. There is an approximate linear relationship between the resistance value and the temperature.
Since the resistance value of the general platinum resistance is not large, the resistance change of the platinum resistance lead and the cable will have a great impact on the temperature measurement results. It is usually eliminated by wiring. The lead form of the measuring element has two wires, three wires and four wires. The products commonly used in the purchase of thermal resistance are three wires and four wires.
The two-wire system refers to a wire drawn from both ends of the thermal resistance. This measurement method is simple, but because the resistance of the connecting line cannot be eliminated, it will cause measurement errors, and it is often used in occasions that do not require short distances. The two-wire connection method is not suitable for thermal resistance with accuracy class A of platinum resistance.
The three-wire system connects one lead at one end of the thermistor root and two leads at the other end. This method is often used in conjunction with bridges. Two wires are connected to the two bridge backs of the bridge, and the other wire is connected to the power supply of the bridge, eliminating the error of wire resistance. This is a method commonly used in industry.
The four-wire system connects two wires at both ends of the root of the platinum resistance, two of which provide a constant current for the thermal resistance and convert the resistance into a voltage signal; the other two wires measure the voltage above the thermal resistance. Due to the high internal resistance of the voltage measuring instrument and no shunt, the measured voltage is completely the voltage at both ends of the platinum resistor. The method has high precision and is suitable for high precision measurement.
The main products of Jinzhou Jingwei Instrument Co., Ltd. are pt20, intrinsic safety constant power thermal flowmeter, pt100 platinum resistor, constant power thermal flowmeter, pt100, pt100 thermal resistor, platinum resistor, thermal flow sensor, thermal resistor, temperature field calibrator, high precision thermometer, oil and gas recovery flowmeter, thermocouple, temperature transmitter, temperature sensor, etc. It has the ability to produce high-quality, high-precision industrial sensors and instrumentation. At present, the use of our products has reached more than two thousand users. "As long as users of Jinzhou's subtle products will be repeat customers". Our company's aim is "to the quality of development, reputation to win the world". Cooperation units: State-owned 171 Factory, Hangzhou Focus Technology Co., Ltd., China Institute of Metrology, Tianxin Instrument Group Co., Ltd. Since its establishment, our company has been striving for perfection and innovation on the premise of meeting the continuous improvement of product quality requirements of users, and has achieved rapid development. China's products have entered an era of high quality, and we have benefited from this era.