III SEMESTER DIPLOMA EXAMINATION 2007 E & C BOARD, ELECTRICAL MEASUREMENTS Question paper

Time : 3 Hours Max. Marks : 100

Instruction: (1) Section – I is compulsory.
(2) Answer six full questions choosing any two full questions each from Section II, III and IV.

SECTION – I

1. (a) Fill in the blanks with appropriate word / words :
(i) Human errors in making measurements are termed as _____
(ii) PMMC is the abbreviation for ____
(iii) _____ used for making AC measurements on high voltage lines.
(iv The range of ammeter can be extended using ____ resistance.
(v) The SI unit of power is ____ .
(b) Explain briefly primary standards of frequency.

SECTION – II

2. (a) Explain the construction of saturated Weston cell.
(b) What are the advantages of MKS system.
(c) Write the dimension of: (i) Current (ii) MMF (iii) Charge (iv) Electrical flux

3. (a) Explain briefly systematic errors.
(b) Explain with example the difference between accuracy and precision.
(c) Explain loading effect.

4. (a) Explain the method of determining series resistance in DC voltmeter with a neat diagram.
(b) State the reasons for electro magnetic damping. How is it classified?
(c) What is torque?

SECTION – III

5. (a) Enumerate various causes of failures in equipments.
(b) Write a brief note on corrective maintenance.
(c) Define failure rate with respect to instruments.

6. (a) Compare PMMC and Electro dynamometer.
(b) Explain the working of single phase watt meter.
(b) What is electrostatic instrument?

7. (a) Explain the working of attractive and repulsive type instrument with a neat diagram.
(b) What are the advantages of PMMC instruments?
(c) List the classifications of moving iron instruments.

SECTION - IV

8. (a) What are the advantages and disadvantages of hot wire instruments?
(b) Give the uses of the following electro dynamometer.
(i) Megger (ii) Watt meter
(c) Give the applications of electro dynamometer.

9. (a) Explain
(i) Current transformer (ii) Voltage transformer
(b) Explain the block diagram, method of calibration of DC ammeter.
(c) What is calibration?

10. (a) Explain what factors does mean time to repairs [MTR] depends.
(b) Distinguish between indicating and recording instruments.
(c) Define the following terms :
(i) Maintainability (ii) Reliability