Electrical Machines MCQs Part 04

31. The number of commutator segments in a 1 machine is equal to the no of
a. coil-sides
b. turns
c. coils
d. slots

32. Dielectric strength of PVC is around
a. 5 kV/mm
b. 10 kV/mm
c. 15 kV/mm
d. 30kV/mm

33. Gaseous insulating material
a. Teflon
b. Sulphur hexafluoride
c. Stealite
d. Phologopite mica

34. Silver finds applications generally as
a. contact material
b. fusing material
c. low temperature insulating material
d. none of the above

35. The fusing current depends on
a. diameter of fuse wire
b. number of strands of wire
c. length of the fuse wire
d. all of the above

36. Class H incillation is normally used in
a. traction motors
b. submersible pump motors
c. single phase motor
d. dc motors

37. An ideal liquid insulating material should have low
a. heat conductivity
b. dielectric strength
c. mechanical strength
d. volatility

38. The electric breakdown strength of an insulating material depends on
a. composition of the material
b. thickness of the material
c. time of application of voltage
d. all of the above

39. Which has lowest dielectric strength
a. Cotton
b. Empire cloth
c. Poreclain
d. Mica

40. In silicon steel designation like E320 The second figure 2 represents
a. specific loss
b. direction of grain orientation
c. magnetic variety
d. non-magnetic variety