How to connect the end face thermal resistor?

End face thermal resistors measure the surface temperature or inner temperature of an object and are often used to measure the temperature of bearings. Industrial thermal resistors are used as temperature measurement sensors and are usually used in conjunction with temperature transmitters, regulators, and display instruments to form process control systems to directly measure or control the temperature of liquids, steam, gaseous media, and solid surfaces within the range of -200℃-500℃ in various production processes. After understanding how end face thermal resistors work, it will be much easier for us to install end face thermal resistors, but it should be noted that the thermal resistor and the display instrument must have the same graduation number; and in order to eliminate the influence of the resistance change of the connecting wire, the three-wire connection method must be used.
Two-wire system: The method of connecting a wire at each end of the thermal resistor to lead out the resistance signal is called the two-wire system: This lead method is very simple, but since the connecting wire must have a lead resistance r, the size of r is related to the material and length of the wire, so this lead method is only suitable for occasions with low measurement accuracy
Three-wire system: The method of connecting a lead at one end of the root of the thermal resistor and two leads at the other end is called the three-wire system. This method is usually used in conjunction with the bridge, which can better eliminate the influence of the lead resistance and is the most commonly used in industrial process control.
Four-wire system: The method of connecting two wires at each end of the root of the thermal resistor is called the four-wire system, in which two leads provide a constant current I for the thermal resistor, convert R into a voltage signal U, and then lead U to the secondary instrument through the other two leads. It can be seen that this lead method can * eliminate the influence of the lead resistance, and is mainly used for high-precision temperature detection.
The thermal resistor adopts a three-wire connection method. The three-wire system is used to eliminate the measurement error caused by the resistance of the connecting wire. This is because the circuit for measuring the thermal resistor is generally an unbalanced bridge. The thermal resistor is a bridge arm resistor, and its connecting wire (from the thermal resistor to the central control room) also becomes a part of the bridge arm resistor. This part of the resistance is unknown and changes with the ambient temperature, causing measurement errors. A three-wire system is used, with one wire connected to the power supply end of the bridge, and the other two connected to the bridge arm where the thermal resistor is located and the adjacent bridge arm, thus eliminating the measurement error caused by the wire line resistance.