1) Write the emf equation for d.c. generator.
2) Describe why armature core in d.c machines is constructed with laminated steel sheets instead of solid steel sheets?
3) Explain why commutator is employed in d.c.machines?
4) Write down the difference between shunt and series field coil construction.
5) Describe how does d.c. motor differ from d.c. generator in construction?
6) How will you modify the direction of rotation of d.c.motor?
7) What do you mean by back emf in d.c. motor?
8) Explain the function of no-voltage release coil in d.c. motor starter.
9) Write down the factors on which speed of d.c.motor depends.
10) Under what situation, does a dc shunt generator fail to generate?
11) A 50 Hz, 400v, 4-pole cylindrical synchronous generator has 36 slots, two –layer winding with full pitch coils of 8 turns each. Mean air –gap diameter is 0.16m, axial length 0.12m and uniform air gap of 2mm. Compute the value of resultant AT/pole and peak air gap flux density. The machine is developing electromagnetic torque of 60 Nm as a generator at a torque angle of 260. What must be the rotor AT/pole? What is the stator AT and the angle it makes with the resultant AT? Also determine the stator current.