Name of the College : DMI College OF Engineering
Department : Electronics & Communication Engineering
Subject Code/ Name : EE-6352 Electrical Engineering & Instrumentation
Degree : B.E
Website : dmice.ac.in
Document Type : Question Bank
Electrical Engineering & Instrumentation : https://www.pdfquestion.in/uploads/dmice.ac.in/1702-EE6352.docx
Electrical Engineering & Instrumentation Question Paper
Unit – I
PART-A :
1. What is the purpose of yoke in a DC machine
2. The core of the armature is laminated in DC machines. Justify
3. What are types of armature windings available in DC machines?
Related : DMI College OF Engineering IT2402 Mobile Communication B.E Question Bank : www.pdfquestion.in/2784.html
4. What is the purpose of commutator in a DC generator?
5. Define back emf.
6. Why series motor cannot be started without any load.
7. How does a series motor develop high starting torque?
8. A 4 pole generator with wave wound armature has 51 slots each having 24 conductors. Flux per pole is 0.01 Weber. At that speed must be armature rotate to give an induced emf of 250v.What will be voltage developed, if the winding is lap connected and armature rotates at the same speed.
9. A 6 pole DC motor has 936 wave connected armature conductors. The useful flux per pole is 0.02 wb and Ra is 0.5?.Calculate
i) The speed and ii) the torque developed when its armature takes 35A at 400V.
10. Write down the speed equation of a DC motor
11. State the functions of interpoles.
12. What are the functions of brushes?
13. If speed is decreased in a DC motor, what happens to the back emf and armature current?
14. A dc motor operates from a 240v supply. The armature resistance is 0.2 ohm. Find the back emf when the armature current is 50A.
15. Give the applications of dc motors.
16. Mention the factors affecting the speed of dc motor.
17. Draw the characteristics of d.c compound motor.
18. Define speed regulation of dc motor.
19. State the voltage equation of a dc motor.
20. How to reverse the direction of a dc motor.
PART-B : (16 marks)
Explain the construction features of a DC Machine
a. Explain the E.M.F Equation of the D.C Generator.
b. Explain the Principle of operation of a D.C Motor.
** Sketch and Explain the load Characteristics of DC shunt and series Generators
** Explain the Performance characteristics of a d.c Series Motor With the relevant derivations to justify their shape.
** Explain the Performance characteristics of a d.c Shunt Motor With the relevant derivations to justify their shape.
** Explain the Speed control Methods of D.C Shunt Motor.
** Explain the Speed control Methods of D.C Series Motor.
UNIT-II
TRANSFORMER :
PART-A :(2 marks)
1.Define a Transformer.
2. What are turns ratio and transformation ratio of Transformer
3. Write the e.m.f equation of two winding transformer
4. .Classify the transformer according to the construction
5. What is step up transformer
6. A sinusoidal flux 0.02wb links with 55 turns of a transformers secondary coil.Calculatethrrms value of the induced emf in the secondary.The supply frequency is 50Hz.
7. A 230/115 V transformer takes a 0.05A at a powerfactor of 0.2 on open circuit.Find the magnetising and working components of no load primary current.
8. Give the principle of transformer
9. Define regulation of a transformer
10. .What are the losses in a transformer? How will you minimise them?
11. Define all -day efficiency and efficiency of a transformer?
12 What are the typical uses of auto transformer
13. Does the transformer draw any current when secondary is open
14. Why transformers are rated in kVA
15. Mention the advantages of auto transformer
16. State the functions of transformer oil.
17.Mention the function of breather in transformer.
18.Determine the optimum value of load resistancefor maximum power transfer if the load is connected to an amliffier of output resistance 150? through a transformer with a turns ratio 5:1
19.Draw the load characteristics of transformer for different types of load.
20. Why transformer is called constant flux machine.
PART-B : (16 MARKS)
** Discuss the construction,and principle of operation of a transformer in detail.
** From first principles, derive the emf equation of a transformer. Also show that the voltage induced per turn is the same, whether it is primary or secondary .
** Explain the behaviour of transformer on no load with phasor diagram.
** Explain the behaviour of transformer on load with phasor diagram
** Develop the equivalent circuit of a transformer.
** List the various losses in a transformer. How these losses can be minimized.(8)