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When talking about Pt100 thermistors, people often discuss their wiring methods and installation. So, do the three different wiring methods for Pt100 thermistors affect the measurement accuracy? Two-wire system: The method in which a wire is connected to each end of the PT100 thermistor in order to transmit the resistance signal is called the two-wire system. This wiring method is simple, but since there is inevitably a wiring resistance r due to the connection wires, and the value of r depends on the material and length of those wires, this wiring method is only suitable for applications where lower measurement accuracy is sufficient. Three-wire system: The configuration in which one lead is connected to one end of the PT100 thermistor, while two leads are connected to the other end, is known as the three-wire system. This approach is typically used in conjunction with bridges, as it helps to minimize the impact of lead resistance. It is the most commonly used method in industrial process control. The use of a three-wire PT100 thermistor is intended to eliminate measurement errors caused by the resistance of the connecting wires. This is because the circuit for measuring thermistors is generally an unbalanced bridge. As one of the bridge arm resistors in a bridge, the connecting wire of the thermistor also forms part of the bridge arm resistance; this portion of the resistance is unknown and changes with ambient temperature, resulting in measurement errors. A three-wire system is employed, with one wire connected to the power supply terminal of the bridge, and the other two wires connected respectively to the bridge arm where the thermistor is located and to the adjacent bridge arm. This approach eliminates the measurement errors caused by the resistance of the wiring; Shaoxing Zhongyi’s PT100 thermistors typically use this three-wire configuration. Four-wire system: The method in which two wires are connected to each end of the PT100 thermistor is known as the four-wire system. Two of these wires supply a constant current I to the thermistor, converting R into a voltage signal U; this signal U is then transmitted to the secondary instrument through the other two wires. It can be seen that this type of lead configuration completely eliminates the influence of lead resistance, and is mainly used for high-precision temperature detection.