JNTU B.Tech II Semester INSTRUMENTATION Examinations, Apr/May 2008

JNTU B.Tech II Semester INSTRUMENTATION Examinations, Apr/May 2008

(Electrical & Electronic Engineering)

Time: 3 hours Max Marks: 80

Answer any FIVE Questions

All Questions carry equal marks


1. (a) Describe the various sources of errors encountered in a measuring system.

(b) What do you understand by the terms

i. Systematic errors

ii. Instrumental errors. [8+8]


2. (a) Explain the common forms of periodic signals with their waveforms.

(b) What is complex form representation of periodic signal? [8+8]


3. What is digital frequency meter? Explain its principle of operation, construction

and working. [16]

4. (a) Explain in detail about integrating type DVM.

(b) Explain the successive approximation conversion techniques. [8+8]


5. (a) Explain the working of a Frequency selective wave analyzer with a neat block


(b) What is harmonic distortion? What are the types of the distortion? Discuss them. [8+8]


6. (a) Discuss the materials used for potentiometers.

(b) A voltage dividing potentiometer is used to measure an angular displacement of 600 and the total angle travel of the potentiometer is 3550. Calculate the voltage output on open circuit if the potentiometer is excited by a 60V source. Calculate the actual value of the output voltage at this setting if a voltmeter of 1M resistance is connected across the output. The resistance of the potentiometer is 1K. Calculate the % error. [6+10]


7. (a) Discuss in detail about strain gauge Rosettes.

(b) The strain gauge having a gauge factor of 2 is connected in a bridge circuit

having an excitation voltage 8V. The resistances are equal.It is subjected to a

strain of 0.006. If this output is to represent 2/3rd of full scale deflection of a

recorder, what should be the gain of the amplifier. The full scale input

voltage of the recorder is 1V. [10+6]


8. (a) Discuss about the radiation receiving elements used in Radiation pyrometers.

 (b) The emitted radiant energy from a piece of metal measured and the temperature is found to be 1065 0C assuming surface emissivity of 0.82. It was later found that the true emissivity is 0.75. Calculate the error in the temperature measurement. [10+6]


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