- 1. What is a basic type of D.C. machine?
- 2. Explain the principle on which a generator works.
- 3. Explain the construction and working of an elementary generator.
- 4. Describe briefly various parts of a D,C. machine.
- 5. Why is a commutator and brush arrangement necessary for operation of a D.C. machine?
- 6. Name the main parts of a D.C. machine and state the materials of which each part is made.
- 7. Enumerate all the parts of a D.C. machine and indicate their functions.
- 8. Give the materials and functions of the following parts of a D.C. machine:
(i) Field poles
(iv) Commutating poles
- 9. Give the constructional features and working principle of a D.C. generator. Draw a cross-sectional view of a 4 pole D.C. generator and label there on all parts. Also sketch the shapes of:
(i) Commutator segment with riser, and
(ii) Armature stamping.
- 10. Give the advantages and uses of lap and wave windings.
- 11. Explain the following terms as applied to a D.C. armature winding.
(i) Front pitch
(ii) Back pitch
(iii) Pole pitch
(iv) Commutator pitch.
- 12. Draw up the winding table for a 4 pole, wave connected armature having 30 coil sides and give a developed diagram of the winding showing the polarity and position of the brushes, the main poles and the direction of motion of the armature for a D.C. motor.
- 13. Draw the developed winding diagram of lap winding for 6 poles, 18 slots with two coil sides/slot, double layer showing therein position of poles, direction of motion, direction of generated e.m.f and position of brushes.
- 14. Derive the e.m.f. equation of a D.C. generator.
- 15. Deduce an expression for the voltage induced in a D.C. generator.
- 16. Write a short note on equiliser rings.
- 17. How are ratings of electrical machines expressed?
- 18. Draw the magnetic circuit of a 4 pole D.C. machine.
- 19. Explain different methods of excitation of D.C. generators with suitable diagrams.
- 20. How are D.C. generators classified?
- 21. What is the difference between a separately excited and a self-excited generator?
- 22. Sketch the following types of D.C. generators:
State with reason(s) where each is used?
- 23. What is the difference between the short-shunt and long shunt compound generators?
- 24. With the help of a neat diagram show power division in a D.C. generator.
- 25. Answer the following questions briefly:
(i) State the principle on which generators operate.
(ii) Name the materials of which the following parts of a D.C. machine are made and why?
(iii) Why are field coils provided in a D.C. generator?
(iv) What is the function of an armature in a D.C. generator?
(v) Of what material are the laminations of an armature made up of?
(vi) What is the function of a commutator?
(vii) What purpose is served by brushes in a D.C. machine?