Difference Between Thermistor and RTD

Thermistor vs RTD

Thermistors and RTDs or Resistance Temperature Detectors are two electrical devices that are used to measure electricity. They are usually used to monitor the temperature of certain devices for purposes of regulation. The main difference between the two is the type of material that they are made of.Thermistors are commonly made with ceramic or polymer materials while RTDs are made of pure metals.

In terms of performance, thermistors win in almost all aspects. The best RTDs only have comparable accuracies to common thermistors while lower classes of RTDs are obviously more inaccurate. This even extends to the cabling of these devices. As cables add resistance to the circuit, using very long wires can alter the reading. While keeping the error levels within acceptable values, thermistors can be wired with thousands of feet of cabling while RTDs can only be used slightly over a hundred feet. This means that when long distances are a must, one must employ transmitters when using RTDs. Response time is also another aspect where thermistors are superior. Thermistors are able to detect sudden changes in temperature much quicker, allowing the connected devices to execute important decisions more promptly.

Although thermistors are generally better compared to RTDs, they are still not the universal devices for temperature monitoring. Compared to RTDs, thermistors can only be used within a smaller range of temperatures. Thermistors can only be used up to 130C while RTDS can be used up to 660C. So, when the temperature of the device that is to be monitored is above 130C, one has no option but to go with RTDs.

Due to the difference in temperature changes that both devices can detect, each device has been preferred in certain types of applications. Thermistors are typically used in common appliances like freezers, air conditioning units, and even on water heaters where the temperature is not very high. RTDs are generally used in industrial applications where temperatures can rise far above what we commonly deal with.

Summary:

1. Thermistors are made out of ceramic or polymer while RTDs are made out of pure metals.

2. Thermistors have equal or better accuracy than RTDs.

3. Thermistors allow for greater cable lengths compared to RTDs.

4. Thermistors have a much faster response time compared to RTDs.

5. RTDs have a greater temperature range compared to thermistors.

6. RTDs are general used in industrial installation while thermistors are used in common home appliances.

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