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Instrumentation and Control Lab

Ex 4: Measurement of Temperature Using Thermocouple

4.1 Objective:

To measure the temperature using thermocouple

4.2 Apparatus:

(i) Thermocouple (ii) Heat bar (iii) Thermometer (iv) OP AMP etc.

4.3 Procedure and Experimental Results:

(i) Design an amplifier or instrumentation amplifier of gain 1000.

(ii) Note down the materials used for construction of the thermocouple used for this experiment.

(iii) Connect the thermocouple with the instrumentation amplifier. Now put the both end of the thermocouple in room temperature and observe the output of the amplifier.

(iv) Put the thermocouple and thermometer inside the water tank and switch on the heater. Wait still the steady state in heating is reached.

(v) Now vary the position of thermocouple starting from the closest point of the heater, observe the temperature of the hot and cold junction as well as output voltage.

(vi) Plot the output voltage versus the temperature difference. Also plot the thermocouple emf versus temperature difference.

(vii) Now repeat the steps (iii) to (vi) while the other junction of the thermocouple is in ice.

(viii) Compare the results with the theoretical values.

(ix) Now determine the room temperature using thermocouple.

4.4 Few Questions for Viva Voce:

(i) What are the different types of thermocouple use in industry?
(ii) Do you know the construction detail of the thermocouple used for industrial purpose?
(iii) What are Seebeck, Peltier and Thomposon effects?
(iv) What is the law of intermediate metal?
(v) What do you mean by compensating lead in thermocouple?

3.5 Reference:

(i) Feedback manual, “complete transducers kit TK2942-001”.
(ii) E O Doebelin and D.N. Manik, “Measurement systems”, Tata McGraw Hill, special Indian edition, 2007.
(iii) A. K. Sawhney and P. Sawhney, “A Course in Electrical and Electronics Measurement and Instrumentation”, Dhanpat Rai & Co PLtd, Seventh edition 2009.