Abstract
In remote measurement systems, the lead wire resistance of the resistance sensor will produce a large measurement error. In order to ensure the accuracy of remote measurement, a novel lead-wire-resistance compensation technique is proposed, which is suitable for a two-wire resistance temperature detector. By connecting a zener diode in parallel with the resistance temperature detector (RTD) and an interface circuit specially designed for it, the lead-wire-resistance value can be accurately measured by virtue of the constant voltage characteristic of the zener diode when reverse breakdown occurs, and compensation can thereby be made when calculating the resistance of RTD. Through simulation verification and practical circuit testing, when the sensor resistance is in 848–2120 Ω scope and the lead wire resistance is less than 50 Ω, the proposed technology can ensure the measuring error of the sensor resistance within ±1 Ω and the temperature measurement error within ±0.3 °C for RTDs performing 1000 Ω at 0 °C. Therefore, this method is able to accurately compensate the measurement error caused by the lead wire resistance in two-wire RTDsand is suitable for most applications.
Highlights
High-precision temperature measurement provides basic data for product development and industrial automation applications to improve product quality and ensure production safety
Zener diode is located should be as close to the as possible, and the ambient temperature in this area where the zener diode is located should be as close to the resistance temperature detector (RTD) as possible, and the ambient should not change significantly due to change the change of the temperature in Region in Region in temperature in this area should not significantly due to the changeA.ofThe theRTD
The proposed technique can be popularized to other applications of remote measurement using of this technique include: The component used is simple and small in size for only one zener diode is resistive sensors with lead wires such as resistive displacement sensors, magnetic field sensors, paralleled with the sensor; the time for measuring is short, because the working point of the zener piezoresistive sensors, etc
Summary
High-precision temperature measurement provides basic data for product development and industrial automation applications to improve product quality and ensure production safety. For remote measurements, the electrical resistances of long connecting lead wires between the RTD and the control room instrument produce an appreciable error in measurement. This unwanted error varies with the length of the lead wires and with ambient temperature variations where the lead wires layout [2]. Methods to reduce or eliminate measurement errors caused by lead wire resistance have been studied in many literatures. Authors in Reference [6,7] presented a method to eliminate lead wire resistance for quarter- and half-bridge interface circuit respectively, Sensors 2020, 20, 2742; doi:10.3390/s20092742 www.mdpi.com/journal/sensors
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