Resistance Temperature Detector or RTD is also known as a Resistance Thermometer. The electronic device is used for measuring temperature by taking the measurement of the resistance within a particular electrical wire. Technically, the wire is defined as the temperature sensor.
Note that RTD comes in handy when there’s a need to measure temperature with a high level of accuracy. There’re other devices such as the PT100, that can also be used to measure temperature. They include thermistors and thermocouples. However, they don’t use the same principle as the Resistance Temperature Detector.
What’s The Construction of RTD?
It’s easy to think that an RTD is a complicated device, which is not true. It comes with a wire wound on a form on notched mica in a manner that it runs across the frame so that it’s small in size. That construction ensures improved thermal conductivity to reduce the overall response time to achieve a high heat transfer rate.
In industrial applications, the RTD coil is within stainless steel to provide optimum protection. It can also be covered in a protective tube or sheath. The construction is also to ensure a negligible physical strain while the coiled wire expands. Also, the length of the wire will increase as the temperature changes further.
The tension and the length of the wire are directly proportional. As a result, the resistance of the RTD wire will change, but that’s not desirable. The main goal is to stop the resistance of the wire to change alongside the changes in temperature.
To achieve an excellent electrical insulation, the RTD wire is positioned between the resistance wire and the sheath. That is the only best way to ensure that the resistance thermometer works as expected.
How Does an RTD Work?
Though we have covered some of the basics up there, it helps you delve a little deeper into detail. An RTD comes with a resistance element alongside some insulated copper wires. Most devices come with a maximum of two copper wires, but some of them have three or four wires.
Note that the resistive element is the one that accurately measures temperature and is usually made of platinum. The reason is that platinum can remain stable for a lengthy period and can withstand extreme temperatures.
Platinum is also used because it has a wide temperature range and a close relationship between resistance and temperature, which is necessary for accurate readings. Other than platinum, nickel and copper can also be used as the resistive element.
The device works on a simple principle; as the temperature of a given metal goes up, so does the resistance to the flow of electricity. When an electrical current is put through a sensor, the device then measures the actual resistance of the same current. The electrical resistance will then increase alongside the temperature within the electrical current.
What Are the Advantages of Resistance Temperature Detector (RTD)?
Just like any other machine, RTD comes with both pros and cons, and it’s important that we look at them in this guide. The device is employed in a vast range of industries, such as white goods, automotive, marine, and other industrial applications.
The good thing with RTD is that, compared to other devices, it’s very accurate and consistent. As such, it can be used to make important decisions in various applications. Also, since the resistive element is made of platinum, the device is generally more stable and can be used for a long time to take temperature readings.
Suppose you need a device that can be used in extreme environments, then you should consider using RTD. It comes with a high-temperature range, so it can be used to measure resistance in a vast range of materials.
Types of RTD
There are many types of RTD, they include;
- SMD RTDs: best for automatic mountings
- Platinum RTDs: comes with three temperature ranges, including medium, cryo, and high
- Glass Wire Round RTDs: works best in applications that need measurements and tests
- Nickel RTDs: best for applications with temperatures ranging between -60C to +200C
Resistance Temperature Detector Closing Thoughts
This might not be a comprehensive guide on how RTD works and its main features. But if you understand the details above, then you’ll be familiar with how the device works and why you need to invest in one.
Sam Collier is the founder of Fifium, a web and mobile application development blog dedicated to sharing expert knowledge and insights in the tech industry. With over 15 years of combined experience among its developers, Fifium started as a small group of like-minded professionals passionate about mobile development and has grown into a respected source of information and guides.
