Electrical Machines MCQs Part 03

21. Which of the following can be worked with higher flux densities?
a. Mild steel
b. Silicon iron
c. Cold rolled silicon steel
d. Hot rolled silicon steel

22. In large bulky materials the uniaxial anisotropy can be induced by
a. cold rolling
b. magnetic anncaling
c. magnetic quenching
d. any of the above

23. Magnetostriction
a. grain oriented magnetic properties
b. represents the upper limit to which magnetic properties can be induced
c. change in dimensions resulting from magnetisation of ferromagnetic materials
d. none of the above

24. An ideal insulating material should have low
a. insulation resistance
b. dielectric strength
c. dielectric loss angle
d. mechanic strength

25. The class of insulation used for large rating HV alternators
a. Y
b. A
c. B
d. C

26. Asbestos has
a. fibrous structure
b. crystalline structure
c. grain oriented crystalline structure
d. none of the above

27. Asbestos can bear a temperature upto ……. without loosing its insulating properties
a. 100 degree
b. 200 degree
c. 300 degree
d. 400 degree

28. Fibre glass insulation can be used upto temperature of
a. 60 degree
b. 80 degree
c. 130 degree
d. 180 degree

29. Raw form of natural rubber is known as
a. malamine
b. milk of lime
c. epoxy
d. latex

30. Which of the following is the characteristics of ceramic insulators?
a. These are hards , strong and dense
b. These are stable at high temperature
c. These are unaffected by commercial acids and alkalies
d. All of the above