Difference Between RTD and Thermocouple

Comparative Points Resistance Thermometer or RTD Thermocouple
Working Principle RTD directly measures the actual temperature of object, because electrical resistance is directly proportional to temperature. Thermocouple measures the temperature difference between hot junction and cold junction.
Material used Metals like Copper, platinum, Nickel etc. Metals like Copper, Iron, Platinum, Rhodium or alloys like Constantan.
Output reading Actual temperature of object. Temperature difference between temperature of cold junction and hot junction.
Temperature range Low range of measurement from – 200°C to 1000°C. Wide range of measurement from – 200°C to 1600°C.
Sensitivity RTD is more sensitive than thermocouple. Less sensitive due to very small emf output.
Effect of change in atmospheric temperature No effect on accuracy of measurement. Affects accuracy of measurement.
Response Better response. Comparatively slow response.
Cost High cost.  Moderate cost.

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