Electrical measurement & measuring instrument

PART-A(2 MARKS QUESTION)

    1.  Define accuracy.

2.  What are the different classifications of resistance?

3.  What is phase sequence?

4.  What is a clamp-on ammeter?

5.  Define Resolution.

6.  Why voltmeter is connected in parallel and ammeter in series with the load?

7.  Define tolerance.

8.  Why mirrors are provided in measuring instrument?

9.  What is the difference between indicating type and integrating type instrument ?

10. What is burden in Instrument transformer?

11. What is multiplying factor in a wattmeter?

12. What is rectifier type instrument?

13. What is controlling torque?

14. Define precision.

15.What do you understand by calibration of a measuring instrument?

16.How damping is provided in measuring instruments?

17.State the advantage of digital multimeter over analog type.

18.State the purpose of using multipliers in measuring instruments.

19.What is the necessity of using copper shading bands in the pressure coil                      magnet of an induction type wattmeter?

20. State the use of Instrument transformer.

21.  Define error.

22.  Distinguish between attraction type and repulsion type MI Instrument.

23.  What is the need of LPF wattmeter?

24.  Write the difference between dynamometer type and Induction type wattmeter.

25.   What do you mean by creeping?

26.   What is the condition for a bridge to be balanced?

27.   Define Ratio error.

28.   What do you understand by phase angle error?

29.  List the various methods used for the measurement of low, medium and high  

  Resistance.

30.  By which instrument the insulation resistance is measured?

PART-B (5 marks question)

1.  Explain Rectifier Type Instrument.

2.  Explain measurement of medium resistance by Wheatstone bridge method.

3.  State the use of CT and PT.

4.  Explain phase sequence indicators.

5.  Explain damping arrangement in indicating instruments.

6.  State with example how can you extend the range of voltmeters and ammeters.

7.  State the errors in dynamometer type wattmeter and methods of their correction.

8.  What is a tachometer? Explain its types.

9.  State the characteristics of digital meters.

10. Explain the method of measuring capacitance by De-Sauty bridge method.

11. Write down the difference in operation of CT and PT.

12. Derive an expression of the deflecting torque of an Electro-dynamometer type Instrument.

13.           At its rated load of 25 VA, a 100/5 A current transformer has an iron loss of 0.20 W and a magnetizing current of 1.5 A. Compute its ratio error and phase angle when supplying rated output to a meter having a ratio of resistance to reactance to 5.

14.           The meter constant of a 230V, 10A watt hour meter is 1800 revolutions per kWh. This meter is tested at half load and rated voltage and unity power factor. The meter is found to make 80 revolutions in 138 second. Determine the meter error at half load.

15. Classify various electrical measuring instruments and explain each of them with all system.

16.    State the advantage and disadvantage of MI type Instrument over PMMC type instrument.

17.    What are the errors in energy meter and how they can be compensated?

18.    Explain the different methods of testing of energy meter.

19.    Derive the expression for measurement of inductance using owen’s bridge method. Also mention its advantages and disadvantages.

20.      Explain the measurement of high resistance by loss of charge method.

PART-C (7 marks question)

1.     Explain two types of controlling arrangement in indicating type of instrument.

2.     Explain principle of operation of PMMC instrument.

3.     Explain principle of operation of dynamometer type wattmeter.

4.     Explain mechanical resonance type frequency meter.

5.     Explain measurement of capacitance by Schering bridge method.

6.     Explain single phase Induction type energy meter.

7.     Explain the measurement of three-phase power by two-wattmeter method.

8.     Explain the construction and principle of single-phase dynamometer type power factor meter.

9.     Explain the construction and principle of Megger.

10. State the objective and working of a synchroscope.

11. Derive the expression for the measurement of unknown inductance by Maxwell bridge method.

12. Explain the working of MI type measuring Instrument with necessary diagram and derive the expression for torque.

13. Explain digital multimeter with the help of a block diagram.

14. With a neat sketch, explain the working principle of an electrical resonance type frequency meter.

15. Write short notes on: a) Digital Voltmeter b) Instrument transformer.