In D.C. machines the usual limit of slot pitch is________________?

Related Mcqs:

1. In D.C. machines, the ________ in field mmf results in increase in size and cost of machines?

   A. increase
   B. decrease
   C. either of the above
   D. none of the above

2. The slot leakage can be calculated by making which of the following assumptions ?

   A. The current in the slot conductors is uniformly distributed over their cross-section
   B. The leakage path is straight across the slot and around the iron at the bottom
   C. The permanence of air paths is only considered. The reluctance of iron paths is assumed as zero
   D. All of the above

3. The usual values of maximum flux densities for distribution transformers using hot rolled silicon steel are______________?

   A. 0.5 to 0.8 Wb/m2
   B. 0.8 to 1.0 Wb/m2
   C. 1.1 to 1.35 Wb/m2
   D. 1.4 to 1.8 Wb/m2

4. The forced oil and air circulation method is usual one for transformers of capacities____________?

   A. upto 5 MVA
   B. upto 10 MVA
   C. upto 20 MVA
   D. 30 MVA upwards

5. When the two coil sides forming a coil are spaced exactly one pole pitch apart they are said to be of_____________?

   A. short pitch
   B. full pitch
   C. either of the above
   D. none of the above

6. The design of mechanical parts is particularly important in case of __________ speed machines?

   A. low
   B. medium
   C. high
   D. any of the above

7. The action of electromagnetic machines can be related to which of the following basic principles __________?

   A. Induction
   B. Interaction
   C. Alignment
   D. All of the above

8. _______________is universally used for windings of electrical machines because it is easily workable without any possibility of fracture?

   A. Silver
   B. Steel
   C. Aluminium
   D. Copper

9. Multiple inlet system of air cooling of turbo-alternators can be used for machines of rating upto_______________?

   A. 10 MW
   B. 30 MW
   C. 60 MW
   D. 150 MW

10. In D.C. machines, ir order to prevent excessive distortion of field form by the armature reaction, the field mmf must be made____________?

    A. equal to that of armature mmf
    B. less in comparison with the armature mmf
    C. large in comparison with the armature mmf
    D. none of the above