Temperature Sensors - Comparing Types
Comparing advantages and disadvantages of thermocouples, RTDs and thermistors temperature sensors.
|Temperature Range||Very wide |
|Short to medium |
|Interchange ability||Good||Excellent||Poor to fair|
|Long-term Stability||Poor to fair||Good||Poor|
|Repeatability||Poor to fair||Excellent||Fair to good|
|Sensitivity (output)||Low||Medium||Very high|
|Response||Medium to fast||Medium||Medium to fast|
|Self Heating||No||Very low to low||High|
|Point (end) Sensitive||Excellent||Fair||Good|
|Size/Packaging||Small to large||Medium to small||Small to medium|
- A thermocouple has two dissimilar conductors forming electrical junctions at differing temperatures. The thermocouple produces a temperature-dependent voltage as a result of the thermoelectric effect and can be interpreted as a temperature measurement.
- A RTD - Resistance Thermometer Detector - are made of a length of fine wire wrapped around a ceramic or glass core. The RTD wire is of pure material - typically platinum, nickel, or copper - with an accurate resistance/temperature relationship. The electrical resistance provides an indication of the temperature.
- A thermistor is a type of resistor made of ceramic or polymer materials. The resistance is - like the RTD - dependent on temperature.