Platinum resistance: working principle and advantages of platinum resistance temperature sensor

Platinum resistance temperature sensors have different resistances depending on the temperature. Connect the platinum resistance to the circuit, and the change in resistance can be known by observing the change in current. This article mainly introduces the working principle and advantages of platinum resistance temperature sensors.

1. Operation principle of platinum resistance temperature sensor

Like thermistors, platinum resistance temperature sensors (RTDs) are also thermistors made of platinum. When measuring voltage to calculate the RTD temperature, the digital multimeter uses a known current source to measure the voltage generated by the current source. The voltage refers to the voltage drop between the two wires plus the voltage between the RTD. For example, the RTD resistance is 100, and the resistance changes by only 0.385 every 1. If the resistance of each lead is 10, it will result in a measurement error of 26, which is unacceptable. Therefore, RTDs should be measured using 4 wire ohms.

RTDs are more stable temperature sensors with better linearity than thermistors. However, RTDs are also slower and more expensive temperature sensors. Therefore, RTDs are very suitable for applications with strict accuracy requirements, and speed and price are not important.

2. Application scope of platinum resistance temperature sensor

Platinum resistance temperature sensor is a temperature sensor used to measure air, soil and water. The sensor consists of a precision platinum resistance temperature measuring element and a protective cover treated with a special process, and is led out from the sensor element through a 4-core shielded signal cable for measurement. It is usually measured by a 4-wire measurement method, which can reduce the measurement error caused by wire resistance. Platinum resistance temperature sensor has excellent compatibility and long-term stability, and is widely used in meteorological and environmental protection departments.

3. Main advantages of platinum resistance temperature sensor

Wide temperature measurement range: Due to the stable characteristics of platinum, it will not cause physical or chemical changes due to high and low temperatures. Platinum resistance temperature sensor is a temperature sensor made of a certain functional relationship between its resistance and temperature. Since the characteristic curve of platinum resistance is nonlinear, the standard relationship between resistance and temperature is given in the form of a graduation table, expressed by the resistance-temperature polynomial function R(t). However, in actual measurement, it is more convenient to use the temperature-resistance function T(r) for measurement and calculation. Platinum resistance sensors have good long-term stability and are often used in protective equipment.

In addition to the above, when using platinum resistance temperature sensors, attention should also be paid to good insulation between temperature sensing elements (double-branch structure) and between temperature sensing elements and the ground, otherwise it will directly affect the accuracy of the measurement results and even affect the normal operation of the instrument. In short, when using platinum resistance temperature sensors to measure temperature, first of all, you must correctly select the model, install and use it reasonably, try to set the method, eliminate various external influences, reduce additional errors, and achieve the purpose of accurate, simple and durable measurement.