Assume that we can either use a thermocouple or a RTD Resist

Assume that we can either use a thermocouple or a RTD (Resistive Temperature Detector) for a given industrial application. Discuss the pros and cons of using a thermocouple versus using an RTD.

Solution

Thermocouple vs Resistance temperature detector:

1. Range of temperature measurement : Thermocouples have higher range of measurement (-300 to 4000⁰F) as compared to RTDs(-60 to 600⁰F).

2.Price: Cost of thermocouple is nearly three times less than that of an RTD.

3.Stability : RTD is stable for years whereas a thermocouple can drift within hours.

4.Size : A thermocuple element wire size is smaller i.e less than 1.6 mm as compared to RTD element wire which is 3-6 mm.

5.Response Time : A thermocouple has a better response time which is less than a second as compared to RTD which has a response time of 2.5-10 seconds.

6.Fragile:A thermocouple is not fragile whereas RTD is fragile.

7.Tolerance: A thermocouple has higher tolerance of measurement i.e 2⁰C as compared to RTD whose tolerance is 0.15⁰C.

8.Technology: RTD technology is better as it uses a platinum wire as compared to a thermocuple which uses voltage created across bimetal junction.