RTD vs Thermistor: Difference and Comparison

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Key Takeaways

1. Due to their linear resistance-temperature relationship, RTDs provide more accurate temperature measurements than thermistors.
2. Thermistors respond faster to temperature changes than RTDs, allowing for quick adjustments.
3. RTDs exhibit better long-term stability and repeatability, making them suitable for applications requiring consistent measurements over time.

What is RTD?

RTD is the abbreviation used for Resistance Temperature Detector. It is defined as the device used to measure temperature change. The principle used in the device RTD is the proportional changes in both resistance and temperature. In other words, the temperature changes when the resistance changes or decreases.

This above statement can be explained through an equation that follows:

R0(1 + a1T + a2T2 + … + anTn)

The device is made up of pure metals like – copper, nickel, platinum, etc. These metals result from used to manufacture RTD devices because they can hold up against high temperatures and have good stability. Despite this advantage, RTD devices show low accuracy. The graph showing the resistance v/s temperature for the RTD device is linear.

What is Thermistor?

A thermistor is a device that measures temperature changes. They are made of semiconductors, which is why they have positive and negative temperature coefficients. If explained in detail, the temperature increases proportionally with resistance in the case of a positive temperature coefficient. In contrast, in the case of a negative temperature coefficient, the temperature increases are inversely proportional to resistance.

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A thermistor can measure the slightest changes in the temperature of the temperature (range -60˚ Celsius to 15˚ Celsius). In contrast, simultaneously, a range of resistors is around 0.5 Ω to 0.75 Ω. It shows a quick response and has a high sensitivity.

The graph showing resistance v/s temperature for the thermistor is non-linear and even comes in a small size. As it has precise accuracy, the price of a thermistor is relatively high. The primary use of a thermistor is to measure the temperature change in home appliances.

Difference Between RTD and Thermistor

1. RTD or Resistance Temperature Detectors are made up of metals like – copper, nickel, platinum, etc., whereas, on the other hand, the thermistor is made up of semiconductors.
2. The time of response of RTD is relatively slow. In contrast, a thermistor responds quickly to even small temperature changes.
3. RTDs are said to be less accurate, whereas comparatively, on the other hand, a thermistor is highly precise in detecting minute temperature changes as they have a negative temperature coefficient.
4. The graph showing resistance v/s temperature for RTD is linear, whereas comparatively, on the other hand, the graph showing resistance v/s temperature for the thermistor is non-linear.
5. An RTD’s range of temperature is up to 850 ˚ Celsius. On the other hand, the range of temperature measured by a thermistor is 114˚ Celsius and -55˚ Celsius.
6. The resistivity of RTD is low, whereas comparatively, on the other hand, the resistivity of a thermistor is high.
7. RTD is large, whereas, on the other hand, a thermistor is small in size.
8. The sensitivity of RTD is low compared to that of a thermistor.
9. The price of an RTD is low, whereas, on the other hand, the price of a thermistor is high.
10. RTD is mainly used in industries to measure temperature changes, whereas comparatively, the other hand, a thermistor is used at home to measure temperature changes.
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Comparison Between RTD and Thermistor

References
1. https://www.emerald.com/insight/content/doi/10.1108/02602280110398044/full/html

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