What are the three wires of a thermal resistor

When using thermal resistors for temperature measurement, we often encounter a configuration with three wires. So, what are the three wires of a thermal resistor respectively?

1.Definitions of the Three Wires of a thermal resistor

The three wires of a thermal resistor are the positive pole wire, the negative pole wire and the compensating wire.

Positive pole wire:

The positive pole wire is connected to the measuring terminal of the thermal resistor and is responsible for transmitting the voltage signal generated by the thermal resistor. When the temperature changes, the resistance value of the thermal resistor will change, and this change is transmitted out in the form of a voltage signal through the positive terminal wire.

Negative terminal wire:

The negative terminal wire is connected to the other end of the thermal resistor. Together with the positive terminal wire, it forms a complete circuit, enabling the thermal resistor to operate normally.

Compensating wires:

Compensating wires are used to compensate for the resistance changes caused by variations in ambient temperature, thereby enhancing the accuracy of measurement. Compensating wires are usually matched with the material of the thermal resistor to ensure the accuracy of the measurement results.

 
2.Can the positive and negative wires be short-circuited

The positive and negative wires should not be short-circuited under normal circumstances. Short-circuiting can cause a short circuit in the circuit, which makes the thermal resistor unable to work properly and may even damage the measuring equipment. If the negative terminal wire breaks or has other faults, it should be repaired or replaced as soon as possible instead of attempting to short-circuit the positive terminal to other lines.

Furthermore, for the term "no wire", if it refers to any other wire except the positive pole wire (such as the negative pole wire or compensating wire), then it also cannot be short-circuited with the positive pole wire. Because doing so will disrupt the normal operation of the circuit, leading to distorted measurement results or equipment damage.

3.Detailed wiring Explanation for Three-wire and three-wire thermal resistors

The standard wiring color for three-wire thermal resistors is usually two red and one white (there may be slight differences among different manufacturers): The two red wires come from the twisted-pair wires at the same end of the platinum resistance. The material and length of the two red wires led out from the other end of the single white wire platinum resistance must be exactly the same; otherwise, it will affect the accuracy compensation effect!

The principle that industrial party members must understand: The resistance of the two red lines will be "mutually cancelled out" by the bridge! Double red wire: Connected to the adjacent bridge arms of the bridge, automatically offsetting the resistance error of the wire. White wire: Comparison of the measured data of the main circuit carrying the excitation current: For the same 100-meter wire, the error of the three-wire system is reduced by more than 70% compared with the two-wire system!

4.Suggestions for the Correct Use of Thermal Resistors

To ensure the accurate measurement of the thermal resistor, the following are some usage suggestions:

（1）Regularly inspect the wiring connection of the thermal resistance to ensure that the positive pole wire, negative pole wire and compensating wires are all intact and correctly connected.

（2）Avoid using thermal resistors in overly humid or high-temperature environments to prevent affecting their performance and service life.

（3）Before using the thermal resistor, carefully read the product manual and install and debug it according to the instructions in the manual.

（4）If any line faults or measurement abnormalities are found, the equipment should be immediately shut down and inspected to prevent further damage to the equipment. By understanding and mastering the functions and roles of the three wires of the thermal resistor, as well as the correct way to use the thermal resistor, we can better ensure the accuracy of the measurement results and the stability of the equipment. In practical applications, if there are any questions or problems encountered, one should consult professionals or seek technical support in a timely manner.