QUESTION BANK

SUB.CODE : EE 6352
SUB NAME : Electrical Engineering and Instrumentation
DEGREE/BRANCH : BE/ECE
YEAR//SEM : II / III
UNIT I - DC MACHINES
PART-A
1. Draw the open circuit characteristics of D.C generator.
2. List the types of D.C motors.Give any one difference between them.
3. Why in a DC machine the armature core should be laminated?
4. In a DC machine the armature is rotating and the field is stationery. True or False.
5. State the losses in a DC machine.
6. State the condition for maximum efficiency in a DC generator.
7. How many number of parallel paths are available in lap & wave windings?
8. State the function of commutator in DC machine.
9. Write the emf equation of DC generator.
10. What is meant by armature reaction?
11. What is meant by excitation?
12. Name the 2 types of armature winding.
13. What is the purpose of field winding of a DC machine?
14. What is the function of brushes in a DC machine?
15. Name the different types of DC generators.
16. List out the essential parts of a DC machine.
17. Define back & front pitch of lap winding in DC machine.
18. What are the effects of armature reaction in DC machine?
19. Draw the load characteristics of DC shunt generator. State why the terminal voltage
decreases when load current increases?
20. Draw the load characteristics of DC series generator.
21. Draw the open circuit characteristics of a DC generator.
22. Write the torque equation of DC motor.
23. A DC series motor should always be started with load-Why?
24. State 2 applications of DC shunt motor.
25. Draw the speed torque characteristics of DC shunt motor.
26. State the condition for maximum efficiency in a DC motor.
27. Explain how to limit the starting current of DC motor.
28. Name the starters used for starting in DC motors.
29. Why are starters necessary for DC motor?
30. What is meant by back emf in DC motor?
31. Mention the different methods of speed control of DC shunt motor?
32. Mention the different methods of speed control of DC series motor?
33. Define critical resistance.
34. Name the different methods of testing available for DC machines.
35. Draw the connection diagram for Swinburne’s test.
36. Draw the connection diagram of a long shunt compound generator.
37. What is commutation in DC machine?
38. State Faraday’s law of Electromagnetic induction and Lenz law.
39. Mention the following functions in DC Machine (i) Commutator (ii) Brushes (iii) Yoke
(iv) Field coils.
40. What are the main constructional element of a DC Machine?
41. What is meant by excitation of dc machine? What are the different methods for the excitation
of DC Machine?
42. What are the necessary conditions for the generators to be self-excited?
43. Mention any 2-popular methods for the speed control of DC Shunt motor.
44. What is meant by motor ? How the Faraday’s Left hand rule is used explain it.
45. Define critical resistance of a dc generator?
46. List the different method of speed control of DC Shunt motor?
47. In speed control of DC Shunt Motor how the armature control method is distinguished
with field control method.
48. What are the different techniques used for the speed control of DC Series Motor?
49. Write the formulae for voltage equation of a DC Motor.
50. What is meant by armature reaction?
51. Write the formulae for generated emf of a Generator.
52. State two applications of DC shunt motor and series motor.
53. What is the significance of back emf Motor?
54. List the different variable and constant losses in electrical machine.
55. What is the basic principle of a DC Generator? How the Faraday’s Right Hand rule is
implemented explain it.
56. Draw the mechanical characteristics of DC Series and DC Shunt Motor.
57. Explain the circuit for Star connection and Delta connection.

PART-B

1. Describe the construction and working of DC Generator.

2. Explain the different methods of speed control of D.C. Motors.
3. With neat diagram explain the working of3 point starter.
4. Explain in detail electrical, mechanical & electro-mechanical characteristics of DC
compound motor.
5. Explain Swinburne’s test with neat diagram.
6. A shunt machine, connected to a 200 V mains has a armature resistance of 0.15 and the
field resistance is 100 . Find the ratio of its speed as a generator to its speed as a motor,
the line current in each case is 75 A.

7. A dc motor takes an armature current of 110 A at 480 V. The armature current resistance
 is 0.2. The machine has 6 poles and the armature is lap connected with 864 conductors.
The flux per pole is 0.05 Wb Calculate
(i) The speed (ii) the gross torque developed by the armature.
8. The armature winding of a 200 V, 4 pole, and series motor is lap connected. There are
280 slots and each slot has 4 conductors. The current 45A and the flux per pole is 18
mWb. The field resistance is 0.3, armature resistance is 0.5 and the iron and friction
losses total 800 W. The pulley diameter is 0.41 m. Find the pull in Newton at the rim of
pulley.
9. A 400 V dc shunt motor takes 5 A at no load. Its armature resistance (including brushing)
is 0.5 and shunt field resistance is 200. Estimate the efficiency when the motor takes 50 A
on full load.
10. Explain the construction of DC machine in detail & derive the emf equation of DC
generator.
11. Discuss the open circuit & load characteristics of DC shunt generator.
12. With a neat sketch, explain the construction and working of DC Motor and explain each parts.
13. Obtain the mathematical expression for the Generated EMF or EMF Equation of a Generator.
14. Calculate the emf generated by 4-pole wave wound generator having 65 slots with 12
conductors per slot when driven at 1200 rpm. The flux per pole is 0.02 Weber.
15. How the DC Motor can be classified and also explain the following characteristics (i)No
Load Saturation characteristics (ii) Internal or Total Characteristics (iii) External
Characteristics.
16. Explain the following methods for speed control of DC Motor (i) Armature Control
Method (ii) Field Control Method.
17. A 250 V Shunt motor takes the total current of 20 A. The shunt field and armature
resistances of 200 ohm and 0.3 ohm respectively. Determine (i) Value of back emf (ii)
Gross mechanical power in armature.
18. The armature of a 6-pole, 600 rpm lap wound generator has 90 slots. If each coil has 4-
turns. Calculate the flux per pole required to generate emf of 288 Volts.
19. A 4 pole d.c shunt generator with a wave wound armature has to supply a load of 500
lamps each of 100W at 250 V. allowing 10V for the voltage drop in the connecting leads
between the generator and the load and drop of 1 voltage per brush, calculate the
speed at which the generator should be driven. The flux per pole is 30mW and armature
& shunt field resistances are respectively 0.05Ω & 65Ω. The number of armature
conductor is 390.
20. A 220V DC shunt motor having an armature resistance of 0.25Ω carries an armature
current of 50A & runs at 600 rpm. If the flux is reduced by 10% by field regulator, find
the speed assuming low torque remains the same.
 UNIT – II TRANSFORMER
PART–A

1. Define regulation in a transformer.

2. Draw the no load phasor diagram of a transformer.
3. What is an ideal transformer?
4. Draw the phasor diagram of an ideal transformer
5. Why transformer core is laminated?
6. Differentiate core type and shell type transformer
7. Why transformer rating is in KVA?
8. What is eddy current loss?
9. Define voltage regulation
10. What is the condition for maximum efficiency in transformer?
11. Name the tests that are performed on a transformer .
12. What is magnetizing current?
13. What are the two components of core loss?
14. Write the emf equation of transformer?
15. Draw the equivalent circuit of transformer
16. Why the efficiency of transformer is higher as compared to other electrical machines?
17. Why the short circuit test is performed on the high voltage side of the transformer?
18. Why core loss is almost negligible in short circuit test?
19. Why core loss is neglected in open circuit test?
20. Does the flux in a transformer core increase with load?
21. Draw the approximate equivalent circuit of transformer
22. What are the losses occurring in a transformer?
23. Why low voltage winding is placed next to the core and after high voltage winding?
24. What is the function of oil in transformer?
25. Why the main flux remain s physically constant from no load to full load?
26. What are the different types of transformer?
27. Give expression for secondary resistance as referred to primary
28. Write the name of material used for transformer core?
29. Name the loss that can be obtained by conducting no load test on the transformer
30. What are the uses of open circuit test and short circuit test performed on a
transformer?
31. What is transformer?
32. Define transformation ratio .
 PART – B

1. Derive EMF equation of a transformer.

2. Explain the operating principle of transformer and derive the emf equation.
3. Draw equivalent circuit of a transformer.
4. Discuss about
i) Transformer losses and efficiency. ii)Explain the working of auto transfer.
5. With neat sketches explain the constructional details of transformer .
6. (i)Describe the tests to determine the core loss and the full load copper loss of a single
phase transformer?
(ii)A 2000/200V transformer has primary resistance and reactance of 2 ohm and 4 Ohm
respectively. The corresponding secondary values are 0.025 Ohm and 0.04 Ohm.
Determine (i) equivalent resistance and reactance of primary referred to secondary
(ii) total resistance and reactance referred to secondary,
(iii) equivalent resistance and reactance of secondary referable to primary,
(iv) total resistance and reactance referred to primary.
7.(i) Draw Kapp’s regulation diagram and explain how the regulation of the transformer in
determined from the diagram?
(ii) The required no load voltage ratio in a 150 kVA, 50 Hz, 1_ transformer 5000/250 v. Find
the efficiency at half rate kVA, UPF and also efficiency at full load 0.8 pf lag if the full
load cu losses are 1800 W. Core losses are 1500 W.
8.(i)The OC and SC tests on a 4 kVA, 200/400 V, 50 Hz single phase transformer gave the
following results: OC tests on LV side: 200 V, 1 A, 100 W, SC test with LV side shorted:
15 V, 10 A, 85 W, Determine the parameters of the equivalent circuit and draw and
equivalent circuit referred to LV side.
(ii) Draw the phasor diagram and explain the operation of a practical transformer on load.
11. Deduce the equivalent circuit of transformer starting from the basic.
12. What are the various losses in a transformer and how each loss varied with load?
Derive the condition for maximum efficiency of a transformer.
13.Give the theory of open circuit and short circuit tests on a single phase transformer and
show how from these tests efficiency and percentage voltage drop of a load of known
magnitude and power factor can be obtained.
14. Describe the tests to determine and explain how the regulation of the transformer is
determined form the diagram.
15. A single phase 2200/250V, 50Hz transformer has a net core area of 36 cm2 and a maximum
flux density of 6 Wb/m2. Calculate the number of turns of primary and secondary.
16. The no load current of a transformer is 5A at 0.3 power factor lagging & supplied at
2.30V,50 Hz. The number of turns on the primary winding is 200. Calculate (a)maximum
value of flux in the core. (b) the core losses (c) magnetizing current.
17. A single-phase transformer with a ratio of 6600/600 V as a load impedance of (4+j3)Ω
connected across the terminals of low voltage winding. Calculate the KW delivered to the
load.neglacting losses in the transformer, find the current taken by it from the supply lines.

UNIT III INDUCTION MACHINES AND SYNCHRONOUS MACHINES

 [A] INDUCTION MACHINES
PART – A

1. Write the principle of operation of a transformer.

2. Name the types of alternators.
3. Why induction motors are called as asynchronous motors?
4. Which type of 3 phase Induction motor develops higher starting torque?
5. How can the direction of rotation of 3 phase Induction motor be reversed?
6. Why an 3 phase Induction motor cannot run at syn. Speed?
7. What is slip of an 3 phase Induction motor?
8. What is the condition for producing maximum torque in a 3 phase Induction motor?
9. Is the maximum torque of a 3 phase Induction motor dependent on the rotor resistance?
10. What is the relationship of developed torque of a 3 phase Induction motor with supply
voltage?
11. How does slip varies with load?
12. What are the losses in 3 phase Induction motor?
13. Draw torque slip characteristics of 3 phase Induction motor
14. Differentiate squirrel cage and slip ring Induction motor.
15. Why a starter is necessary to start an Induction motor?
16. What are the various types of starters used for SCIM?
17. Draw the equivalent circuit of 3 phase Induction motor
18. Write the applications of 3θ Induction motor
19. What are the various methods used for speed control of 3 phase Induction motor?
20. Why single phase induction motor is not self starting?
21. What is double field revolving theory?
22. What is meant by Induction motor?
23. What are the two types of 3 phase Induction motor?

PART – B

1. Describe the construction and working of 3 phase induction motor.

2. Explain the working principle of 3 phase Induction motor
3. Derive the expression for torque of an 3 phase Induction motor and obtain the condition for
maximum torque.
4. Draw and explain the torque speed characteristics of 3 phase Induction motor?
5. Explain the construction and operation of 3 phase Induction motor
6. Explain the different methods of speed control of 3 phase Induction motor
7. Explain double field revolving theory of 3 phase Induction motor
8. Explain different types of starters used for 3 phase Induction motor
9. Draw the Equivalent circuit diagram for a Three phase Induction Motor and at any slip.
And also explain (i) Equivalent circuit of the rotor (ii)Transformer Equivalent circuit for
Induction Motor.

10. A 3300 V, 10 pole, 50 Hz, three-phase star connected motor has slip ring rotor
 resistance per phase = 0.015and standstill reactance per phase = 0.25 Ohm. If the motor
runs at 2.5 percent slip on full load.Find,
(i) the speed of the motor.
(ii) speed at which the torque will be maximum.
(iii) the ratio of maximum torque to full load torque.
10. Explain the torque Vs Slip characteristics of a slip ring three phase induction motor?

[B] SYNCHRONOUS MACHINES

PART-A
1. Write the advantages of stationery armature and rotating field in an alternator.
2. Compare salient & non-salient pole synchronous machines.
3. Deduce the relation between the number of poles, frequency and speed of the alternator.
4. State the advantages & disadvantages of using short pitched & distributed winding in
alternator.
5. Write short notes on the following: Turbo-alternators, armature reaction.
6. Distinguish between hydro & turbo generators.
7. State the working principle of alternator.
8. What is meant by full pitched & short pitched windings?
9. What is meant by winding factor?
10. Why alternators are rated in KVA rather than in KW?
11. What is meant by synchronous impedance of alternator?
12. Define regulation in alternator.
13. What type of rotor is adopted for high speed alternators?
14. Name the 2 types of alternators depending on rotor construction.
15. Why are salient pole alternators more suitable for low speed & non salient pole for high
speed operation?
16. What is an exciter?
17. What is the effect of armature reaction for an alternator for zero power factor lagging?
18. What is hunting?
19. Write the torque equation of synchronous mot
20. What are the advantages of brushless alternator?
21. List the applications of hysteresis motor.

PART-B

1. Discuss methods of starting of synchronous motor.

2. Discuss torque equation synchronous motor.
3. Write short notes on brushless alternator & hysterisis motor.
4. Explain how to calculate regulation using emf method
5. A 3 phase 12 pole synchronous machine has a star connected full
pitch winding with108 slots and 12 conductor s per slot. The flux per
pole is 50 mWb and sine distributed. The speed of rotation is 500 rpm. Find the
frequency, phase emf and line emf.

6. Explain the construction of salient pole synchronous machine?

7. A 600 V, 600 KVA single phase alternator has Ra =0.3 _. An exciting current of 5 A
produces an emf of 400 V, on open and an armature current of 200 A on short circuit.
Calculate a.Synchronous impedance
b. The full load regulation with 0.8 p.f lagging.
8. Derive the induced emf equation of an alternator.
9. From the following test results, determine the voltage regulation of A 2000 V single
phase alternator delivering a load current of 100 A at 0.8 lagging p.f . Test results: An
excitation of 2.5 A produces a current of 100 A in the stator winding on short circuit and
an emf of 500 V on open circuit. Assume an effective resistance of 0.8.
10. Explain the construction of synchronous machine & derive the emf equation.
11. Explain how to calculate regulation using mmf method.
12. In synchronous Motor explain the following terms (i) Torque Equation (ii) V-Curve
Characteristics.

UNIT IV BASICS OF MEASUREMENT AND INSTRUMENTATION

PART-A

1. What is meant by error in measurement system?

2.What is transducer?
3. What is meant by error? Classify.
4. What is meant by static and dynamic characteristics?
5. What is meant by Standard and list out its types?
6. What is the need for measurement and what are its types?
7. Write the need for Calibration
9. What is the function of manipulation element in a measurement system?
10. What are Primary standards? Where are they used.?
11. How are instruments classified?
12. What is an absolute instrument? Give examples
13. What is a secondary instrument? Give examples.
14. Why MI instruments can be used on both AC and DC?
15. What are the errors that occur in MI instruments?
16. What is meant by sensitivity?
17. Define accuracy and resolution.
18. What is meant by static characteristics in measurement system? Mention any 4-static
characteristics of instrumentation.
19. Define the following static characteristics (i) Accuracy (ii)Precision (iii)Span (iv) Static
sensitivity.
20. What is meant by dynamic characteristics in measurement system? Mention any 4-
dynamic characteristics of measurement system.
21. What is meant by error ? Mention the different types of errors produced in
measurement system.

22. How the active transducer is distinguished with passive transducer? Give examples for
 each.
23. What is meant by analog and digital transducer ? Give examples for each.
24. How the primary transducer is distinguished with secondary transducer ? Give
examples for each.
25. What is meant by variable resistance type or potentio meter ? How the potentio meter
can be classified?

26. Draw the schematic diagram for translational type potentio meter and also write the
mathematical expression for output voltage.
27. Mention the different materials used for potentio meter.
28. What is meant by strain gauge ? And also define the term Piezo resistive effect.
29. What are the different materials used for the construction of strain gauges ? And also
write the formulae for gauge factor.
30. What is meant by semi conductor type strain gauges ? Mention the different materials
used for the construction and also write the advantages of it.
31. What is meant by thermistor ? Why thermistor is said to be Negative Temperature
Coefficient of Resistance(NTCR) ?
32. What is meant by RTD ? Write the mathematical expression for RTD? Why RTD is said
to be Positive Temperature Coefficient of Resistance(PTCR) ?
33. Draw the schematic diagram of parallel plate capacitor. And also write the
mathematical expression for it.
34. Mention any 4-applications of capacitance type transducer.
35. What is meant by piezo electric effect ? Give any 4-materials used for piezo electric
effect.
36. What is meant by variable inductive transducer ? Mention the different types of
variable inductive transducer.
37.What is meant by Linear Variable Differential Transformer(LVDT) ? Draw the schematic
diagram of LVDT. And also write the output equation for
(i) Null Position (ii) Left Position (iii) Zero Position.

PART-B

1. Explain the working of following sensors

i)Strain Gauge
ii)Thermistor
2. Explain the operation of
i)Capacitor microphone
ii)piezoelectric transducer
3. Explain static and dynamic characteristics of Measurement systems .
4. Explain in detail variable resistive and capacitive transducer.
5. What are the functional elements of generalized instrumentation systems?
6. (i)Explain types of error in measurement and instrumentation systems.
(ii)Explain units and standards.
7. Explain Piezoelectric transducer.
8. With a neat diagram explain in detail the Construction of a RVDT .
9. With a neat diagram explain in detail the Construction of a LVDT.
10.Explain the following characteristics of measurement system (i) Static Characteristics (ii)
Dynamic Characteristics.
11. What is meant by error in measurement system? Explain the following types of errors (i)
Gross Error (ii) Systematic Error (iii) Random Error.
12. Explain the following types of transducer (i) Active and Passive Transducer (ii) Primary and
Secondary Transducer (iii) Analog and Digital Transducer (iv) Transducer and Inverse
Transducer.
13. What is meant by variable resistance transducer or potentio meter ? Explain the following
types of potentio meter (i) Translational type Potentio meter (ii)Rotational type potentio
meter (iii) Helical type potentio meter. And also write the advantages, disadvantages and
applications of it.
14. What is meant by Piezo electric effect ? Obtain the mathematical expression for gauge factor
in strain gauge. Explain the different types of strain gauges (i) Wire wound type strain gauges
(ii) Bonded metal foil strain gauges (iii) Thin film type of strain gauges (iv) Semi conductor
type strain gauges (v) Rosettes. And also write the applications of strain gauges.
15. Explain the principle, construction, working, mathematical expression of RTD. Also explain
the following RTD Scheme (i) Two lead arrangement (ii) Three lead arrangement (iii) Four
lead platinum thermometer.
16. Explain the principle, construction, working, mathematical expression of Thermistor.And
also write the advantages, disadvantages and applications of it.
17. Explain the following types of capacitive type transducers (i) Parallel plate capacitor (ii)
Cylindrical plate capacitor (iii) Capacitor type transducer as microphone.
18. What is meant by piezoelectric effect ? Mention any 4-materials used for piezoelectric effect.
Obtain the expression for output voltage and equivalent circuit of piezoelectric crystal. And
also write the advantages, disadvantages and applications of it.
19.What is meant by variable inductive transducer ? Explain the following different types of
variable inductive transducer (i) Variation of self - inductance of the coil (ii) Variation of
mutual inductance of the coil (iii) Production of eddy current.
20. Explain the construction, working and characteristics of LVDT. And also write the
advantages, disadvantages and applications of it.
21. Explain the construction, working and characteristics of RVDT.

UNIT V ANALOG AND DIGITAL INSTRUMENTS

PART-A

1 .Compare analog and digital instruments.

2.Write the working principle of Q meter.
3. What is Q meter?
4. What are the applications of Q meter?
5. What are the different connections in Q meter?
6. What is digital instrument?

7. What is analog instrument?

8. What are the advantages of digital instruments over analog instruments?
9. What is digital voltmeter?
10. Compare analog and digital instruments.
11. What is DVM?
12. Draw the block diagram of Integrated DVM.
13. What is Q factor?
14. List the types of DC and AC bridges?
15. Mention any 4-different types of digital voltmeter.
16. Draw the block diagram of ramp type digital voltmeter.
17. What is digital multimeter ? Mention the different quantities measured by digital multimeter.
18. Write some of the advantages of digital multimeter.
19. How the resistance can be classified into low, medium and high value? And also Mention the
different instruments used for measure purpose.
20. What is meant by bridges ? Mention any 2-examples for source and detectors for bridges.
21. Draw the general circuit diagram for AC bridge. And also write the general equation for
magnitude and impedence of it .
22. Mention any 4-examples for AC bridges for measurement of different quantities.
23. What are the advantages of digital mode of operation compare with analog mode of
operation.
24. What is meant by storage oscilloscope ? Mention any 2-applications of storage oscilloscope.
25. Write some of the advantages of digital voltmeter compare with analog voltmeter.
26. How the analog instrument is distinguished with digital instruments explain it ?

PART-B

1. With neat diagram explain the operation of storage oscilloscope.

2. With neat diagram explain the working of Wein’s bridge for capacitance measurement.
3. What are the various sources of errors in Q-Meter?
4. (i) Discuss in detail about Kelvin double bridge.
(ii)With a neat diagram explain in detail about Hay Bridge.
5. With the neat diagram explain Anderson Bridge and Schering Bridge.
6. Explain with block diagram, the operation of ramp type DVM.
7. Write brief notes on Digital Storage Oscilloscope .
8. Explain the working of electronic multi-meter with necessary diagrams .
9. Explain the following types of Digital voltmeter (i) Ramp type Digital Voltmeter (ii)
Dual slope integrating type Digital Voltmeter.
10. Draw the block diagram and explain the following types of voltmeter (i) Successive
approximation type DVM (ii) Potentiometric type DVM .
11.Draw the block diagram of Digital MultiMeter. How it can be used for the measurement of
(i) DC Voltage (ii) AC Voltage (iii)DC Current (iv) Resistance. And also write the advantages of
it.

12.Draw the schematic diagram of storage oscilloscope and explain each parts.
13.Draw the circuit diagram of Wheat stone bridge. How it can be used for the measurement of
medium value of resistance.
14.Draw the circuit diagram of Kelvin’s double bridge. How it can be used for the measurement
of low value resistance.
13. Draw the circuit diagram of Anderson’s bridge. How it can be used to measure the value of
self inductance explain it.
14. Draw the circuit diagram of Schering bridge. How it can be used to measure the value of
capacitance explain it.
15. Draw the circuit diagram of Wien’s bridge. How it can be used to measure the value of
frequency explain it.
16. What is meant by Q-factor of a coil? Draw the circuit diagram of Q-meter. How it can be
used to measure the value of Q-factor of the coil explain it.
17. How the effective resistance at high frequency can be measured by Q-Meter explain it.