JNTU III B.Tech II Semester Supplimentary Examinations, Aug/Sep 2008

JNTU III B.Tech II Semester Supplimentary Examinations, Aug/Sep 2008

INSTRUMENTATION

(Electrical & Electronic Engineering)

SET-I

1. Enumerate the various sources of error encountered in a measurement system.

2. Define band width of a signal and explain the way signals are classified according the their band width.

 

3. (a) Why is a delay line used in the vertical section of the oscilloscopes.

(b) What are the advantages of dual trace over dual beam for multiple-trace oscilloscopes.

 

4. With a neat block diagram explain the circuit of a digital frequency meter, in detail.

5. (a) Explain the method of measurement of linear displacement using potentiometer.

(b) A heliport is provided with 40 turns/mm. The gearing arrangement is such that the motion of the main shaft by one revolution causes 5 revolutions of the potentiometer shaft. Calculate the resolution of the Potentiometer?

 

6. (a) Discuss in detail the operation of LVDT?

(b) What are the advantages and disadvantages of LVDT?

 

7. (a) With the help at a circuit diagram, explain the measurement of low pressure using ionization type gauge.

(b) Explain the measurement of pressure using resistive transducer.

 

8. (a) Explain with a neat sketch the measurement of angular velocity using toothed rotor variable reluctance tachometer. Give the advantage and disadvantage of this method.

(b) An inductive pick off operating from a 120 tooth wheel is used with a digital frequency meter to measure the speed of rotation of the shaft on which the wheel is mounted. The gating period is set to 0.01 sec and a reading of 0030 is obtained on the four digit display. What shaft speed does this in r.p.s. If the available gating periods are 102, 103, 104, 105, 106 and 107micro seconds respectively, what would be the optimum setting of gating period for making this measurement.

 

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