Thermocouples are the most widely used temperature sensors on the planet due to their combination of wide temperature capabilities, ruggedness, and low cost. Thermocouples are used in applications that range from home appliances to industrial processes, to electric power generation, to furnace monitoring and control, to food and beverage processing, to automotive sensors, to aircraft engines, to rockets, satellites and spacecraft.
When it comes to high temperatures, small size, fast response, high vibration or shock, most times you will find thermocouples providing the temperature measurements.
It is not practical to compare RTDs (Pt100 and others) and thermocouples generally. However, if we compare their performance in terms of specific criteria, we can see which is best suited for specific applications. Thermocouples are best for working at high temperatures. New manufacturing techniques have improved the measurement range of RTD probes, but more than 90% of RTDs are designed for temperatures below 400°C.
In contrast, some thermocouples can be used at up to 2500°C. Thermocouples are generally cheaper than RTDs...