In many appliances, whether they’re electronic or industrial applications, there’s one tiny film component that makes all the difference when it comes to temperature measurement. This is the resistance temperature detector or RTD, a popular temperature sensor on today’s market. It works on the basis of electrical resistance that will increase as the temperature of the metal in the RTD rises. You can measure this resistance in ohms, and depending on the metal used inside the RTD, you can convert the reading to temperature.

This method is especially respected for its accuracy and reliability. RTDs will still function well in extreme conditions. For most industries, these characteristics are essential, which is why RTDs are so high in demand. The market for these sensors may seem confusing to some. For example, you’ll also come across different terms like ‘PT100”. Combining information from various reliable resources and articles, we’ll provide you with an explanation of these terms so you can make informed decisions when it comes to temperature sensor components in your industry.

Is an RTD the Same As a PT100?

You may have heard people referring to the PT100 when discussing temperature sensors. If you’re wondering what the difference is between a RTD and a PT100, the answer is there’s no difference.

A PT100 is a type of sensor that belongs to a group of resistance temperature detectors. They’re made of platinum and may also be known as platinum resistance thermometers (PRT). RTD and PT100 sensors are used interchangeably, but they’re both resistance thermometers. While the PT100 is the commonly used device for most applications, you can also get the PT250, PT500 and PT1000.

What About Copper and Nickel RTDs?

The wire of the RTD can be made with either platinum, copper or nickel. Platinum is the most favored material because of its stable resistance-temperature relationship over a larger temperature range. In comparison, nickel has a limited temperature change because the resistance-temperature relationship becomes non-linear over 300°C. Copper, on the other hand, has a linear resistance-temperature relationship, but the copper begins to oxidise at moderate temperatures, so its uses are limited to a temperature of 150°C.

When Should You Use an RTD?

A RTD is used by many industries for its accuracy and stability over a wide temperature range. Industries will use a RTD for various applications such as:

  • Stoves and grills
  • Air conditioners
  • Refrigerators
  • Production of textiles
  • Processing of food
  • Petrochemicals

 The RTD is an excellent device for measuring temperature of air, gases and liquids.

How to Select an RTD

While a RTD can be used for a variety of applications, selecting the right RTD is based on certain criteria. You need to consider the temperature rating as well as the accuracy, interchangeability and tolerance required. Time response is another important consideration as well as the distance from the measuring equipment.

Companies such as Pyrosales will assist you in deciding whether to go with a 2-wire, 3-wire or 4-wire configuration for the construction of the RTD. The 3-wire is the most popular option for industrial settings while the 2-wire construction is fine when close accuracy is not vital. The 4-wire construction is most commonly used in laboratories where close accuracy is essential.

Final Thoughts

A resistance temperature detector is a valuable device being used in many industries to obtain stable and accurate readings. It’s easy to get confused when you hear about the PT100 and how to go about selecting the right RTD for your needs, but once you know that a PT100 is the same as a RTD, you can focus on picking the right temperature sensor for the job.