Help with a question about thermocouples

estrella99

Help with a question about thermocouples [Copy link]

It is required to measure the temperature between -100°C and +100°C using a K-type thermocouple and perform cold junction compensation according to the RTD (resistance temperature detection device) circuit in the figure below. RT is Pt100 with α = 0.385%/K at 0°C. 1. Derive the output voltage equation as a function of the thermopile sensitivity SK and RT value. 2. Determine the condition that the resistor should satisfy to obtain zero output when Ta = 0°C. 3. If R2 and R3 are selected so that the output of the bridge circuit formed by them together with RT and R1 can be considered linear. Try to determine their values for cold junction compensation over the entire range of Ta. 4. Determine the gain of the instrumentation amplifier that gives an output voltage of -1V to +1V; determine the maximum offset voltage of the instrumentation amplifier that limits the error to a maximum of 0.1°C.

maychang

This is no longer a question about analog circuits, it's simply a math problem.

To solve this problem, we must first find the power series expression of the K-type thermocouple temperature differential electromotive force, which can solve problems 1 and 2. From the result of problem 1, we can deduce problem 3.