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RTD, Thermistor, Thermocouple Comparison Chart



Hardware: Multifunction DAQ (MIO)>>M Series>>PCI-6229

Problem:
I am trying to decide what type of temperature sensor I should use in my application. What are the advantages/disadvantages of using an RTD (resistance temperature detectors), a thermocouple, or a thermistor sensor?

Solution:
Temperature Measurement Comparison Chart
Criteria Thermocouple RTD Thermistor
Temp Range -267°C to 2316°C -240°C to 649°C -100°C to 500°C
Accuracy Good Best Good
Linearity Better Best Good
Sensitivity Good Better Best
Cost Best Good Better


Thermocouples are inexpensive, rugged, and have a fast response time but are less accurate and the least stable and sensitive.  Thermocouples also read only relative temperature difference between the tip and the leads while RTD's and thermistors read absolute temperature. 

RTD's are the best choice for repeatability, and are the most stable and accurate.  However they have a slow response time and because they require a current source they do have a low amount of self heating. 

Thermistors have a fast output and are relatively inexpensive but are fragile and have a limited range.  They also require a current source and do experience more self heating than an RTD and are nonlinear.

Related Links:

National Instruments: Temperature Solutions

NI Developer Zone: Temperature Measurements with Thermocouples: How-To-Guide
NI Developer Zone: Temperature Measurements with RTD's: How-To-Guide

[External Link] Wikipedia: Resistor Thermometer (RTD)
[External Link] Wikipedia: Thermocouple
[External Link] Wikipedia: Thermistor



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Report Date: 05/03/2007
Last Updated: 12/21/2010
Document ID: 492HRI0L

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