Schematic diagram of two-wire wiring diagram for RTDs

Time: 2025-01-06
Equipment Configuration:RTD

Thermal Resistance (Thermal Resistance), referred to as thermal resistance, is an important sensor for measuring temperature.

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Thermal resistor two-wire wiring diagram

Thermal Resistance (Thermal Resistance), referred to as thermal resistance, is an important sensor for measuring temperature. It uses the characteristic that the resistance value of metal conductors changes with temperature changes to convert the temperature signal into a resistance signal, thereby measuring and controlling the temperature. Thermal resistors are used in industrial automation, HVAC, medical equipment, automotive electronics and other fields.

According to the different lead connection methods, thermal resistors can be divided into three types: two-wire system, three-wire system and four-wire system. Among them, the two-wire thermal resistor has a simple structure and low cost, and is suitable for occasions where the measurement accuracy is not high. This article will introduce the thermal resistor two-wire wiring diagram in detail, and conduct an in-depth analysis of its working principle, advantages and disadvantages, and application scenarios.

1. Thermal resistor two-wire wiring diagram

The above figure shows the thermal resistor two-wire wiring diagram. Among them, A and B respectively represent the two pins of the thermal resistor, which are connected to the secondary instrument (such as temperature transmitter, PLC, etc.). It should be noted that the two pins of the two-wire heating resistor do not distinguish between positive and negative poles and can be connected arbitrarily.

2. Working Principle

The working principle of the thermal resistance two-wire system is based on the resistance temperature effect of the metal conductor. When the temperature rises, the lattice vibration of the metal conductor intensifies, and the resistance to electron movement increases, causing the resistance value to rise. By measuring the change in resistance value of the thermal resistor, the measured temperature can be calculated.

The two pins of the two-wire heating resistor are responsible for the functions of current transmission and signal acquisition at the same time. When current flows through the thermal resistor, a certain voltage drop will occur. The secondary instrument can calculate the measured temperature by measuring the voltage drop and based on the known temperature-resistance characteristic curve of the thermal resistor.

3. Advantages and Disadvantages

3.1 Advantages

Simple structure, easy to install and maintain. Low cost and high cost performance. Suitable for occasions that do not require high measurement accuracy. 3.2 Disadvantages

The lead resistance will affect the measurement results, resulting in large measurement errors. Not suitable for long distance temperature measurement. The anti-interference ability is weak.

4. Application scenarios

Thermal resistance two-wire system is suitable for occasions where the measurement accuracy is not high and the measurement distance is short, such as:

Household appliance temperature control, such as electric water heaters, Rice cooker etc. Temperature monitoring of simple industrial equipment, such as motors, water pumps, etc. Agricultural greenhouse temperature control. Ambient temperature monitoring.

5. Precautions

When using the two-wire thermal resistor system, you need to pay attention to the following matters:

Choose the appropriate type and specification of the thermal resistor to ensure that its measurement range and accuracy meet actual needs. . Keep the lead length as short as possible and use wires of the same material and diameter to reduce the impact of lead resistance. Avoid placing leads close to sources of strong electromagnetic interference to avoid affecting measurement accuracy. Calibrate the thermal resistor regularly to ensure measurement accuracy.

6. Summary

The thermal resistance two-wire system is a simple and economical temperature measurementSolution, suitable for occasions where measurement accuracy is not required. In practical applications, we need to choose the appropriate thermal resistor wiring method according to the specific situation and pay attention to relevant precautions to ensure that the measurement results are accurate and reliable.

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