MCQs of DC Machines (Electrical Machine - I - 3140913)

Showing 31 to 40 out of 167 Questions

31.

What is/are the necessary conditions for voltage build up in a self-excited generator?

(a)	Poles should contain residual flux
(b)	Field winding should be properly connected to the armature winding
(c)	Field winding resistance should be less than critical resistance
(d)	All of the above

32.

No-load saturation characteristics are plotted between

(a)	no-load voltage and field current
(b)	no-load voltage and armature current
(c)	short circuit current and field current
(d)	short circuit current and armature current

33.

The effect of __________ on main field flux is known as armature reaction.

34.

Armature flux is__________ with respect to main field flux or main field poles?

35.

Cross magnetization effects which of the following?

(a)	commutation
(b)	reduction in main field flux
(c)	reduces the terminal voltage
(d)	both 2 and 3

36.

Demagnetization effects which of the following?

(a)	commutation
(b)	reduction in main field flux
(c)	reduces the terminal voltage
(d)	both B and C

37.

Brushes are always placed on __________ , in order to achieve sparkles commutation?

38.

Flux density under trailing pole tips in case of generator will

39.

Flux density under leading pole tips in case of generator will

40.

Which of the following is/are effects of armature reaction?

(a)	increase the iron loss
(b)	increase the maintenance and repair
(c)	increases the design cost
(d)	all of the above

Showing 31 to 40 out of 167 Questions