Temperature Sensors - Comparing Types
Comparing advantages and disadvantages of thermocouples, RTDs and thermistors temperature sensors.
| Attribute | Thermocouple | RTD | Thermistor |
|---|---|---|---|
| Cost | Low | High | Low |
| Temperature Range | Very wide -350 oF +3200 oF |
Wide -400 oF +1200 oF |
Short to medium -100 oF +500 oF |
| Interchange ability | Good | Excellent | Poor to fair |
| Long-term Stability | Poor to fair | Good | Poor |
| Accuracy | Medium | High | Medium |
| Repeatability | Poor to fair | Excellent | Fair to good |
| Sensitivity (output) | Low | Medium | Very high |
| Response | Medium to fast | Medium | Medium to fast |
| Linearity | Fair | Good | Poor |
| Self Heating | No | Very low to low | High |
| Point (end) Sensitive | Excellent | Fair | Good |
| Lead Effect | High | Medium | Low |
| 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.
