What's the Difference and Which Should You Use

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What is the difference between a resistance temperature detector (RTD) and a thermocouple? Both RTDs and thermocouples are sensors used to measure temperature, such as Fahrenheit and Kelvin. These devices are used in a wide range of applications and settings, often presenting people with the dilemma of choosing between RTDs or thermocouples. Each temperature sensor has its own advantages and disadvantages, making them suitable for certain conditions and environments.

RFQ Temperature sensors RTD vs Thermocouple Table of Contents Casing is heat resistant Thermocouple Bimetallic thermometers Temperature transmitters What is RTD? RTDs are made of metal wires, usually copper or platinum, that provide resistance to the flow of electricity. The resistance of an RTD changes as its temperature Email Data  changes, allowing it to be used as a gauge to measure heat. Thermocouples are considered more accurate than RTDs because they have a linear relationship between resistance and temperature. RTDs are less affected by electromagnetic fields than thermocouples. RTD working principle The full English name of RTD is "Resistance Temperature Detector", so to be precise, it should be translated as "Resistance Temperature Detector". An RTD is a special type of resistor whose resistance value increases as temperature increases and decreases as temperature decreases. In industry, this feature is used for temperature measurement, so the RTD is commonly known as "Thermistor" . RTD working principle Not all metals are suitable for making RTDs.



Materials meeting this characteristic must meet the following requirements: The resistance value of the metal has a linear relationship with the temperature change potential; The metal is more sensitive to temperature changes, that is, the resistance change (temperature coefficient) caused by unit temperature changes is relatively large; The metal is resistant to fatigue caused by temperature changes and has good durability; There are not many metals that meet this requirement. Common RTD materials are: platinum (Pt), nickel (Ni) and copper (Cu). Take, for example, platinum heat resistance. According to different resistance values, it can be divided into Pt50, Pt100, Pt200, Pt500 and Pt1000. The numerical value in the name indicates the resistance value of the thermal resistance at 0 degrees Celsius. For example: Pt100 indicates that the resistance value of the sensor at 0°C is 100Ω.