Electrical machine design Archives - Page 4 of 18 - MCQ and Quiz for Exams

31. Multiple inlet system of air cooling of turbo-alternators can be used for machines of rating upto

10 MW

30 MW

60 MW

150 MW

Detailed SolutionMultiple inlet system of air cooling of turbo-alternators can be used for machines of rating upto

32. Which of the following methods does not take into account the maximum temperature rise under variable loadconditions ?

Equivalent power method

Equivalent current method

Method of average losses

Equivalent torque method

Detailed SolutionWhich of the following methods does not take into account the maximum temperature rise under variable loadconditions ?

33. In a 3-phase power measurement by two wattmeter method the reading of one of the wattmeter was zero. The power factor of the load must be

unity

0.5

0.3

zero

Detailed SolutionIn a 3-phase power measurement by two wattmeter method the reading of one of the wattmeter was zero. The power factor of the load must be

34. A sensitive galvanometer produces large deflection for a

small value of current

large value of current

large value of power

large value of voltage E. none of the above

Detailed SolutionA sensitive galvanometer produces large deflection for a

35. Alternating current is measured by

induction ammeter

permanent magnet type ammeter

electrostatic ammeter

moving iron repulsion type voltmeter

Detailed SolutionAlternating current is measured by

36. The desirable static characteristics of a measuring system are

accuracy and reproducibility

accuracy, sensitivity and reproducibility

drift and dead zone

static error

Detailed SolutionThe desirable static characteristics of a measuring system are

37. ________ cooling is the process of dissipating the armature and field winding losses to a cooling medium circulating within the winding insulation wall

Direct

Indirect

Conventional

Any of the above

Detailed Solution________ cooling is the process of dissipating the armature and field winding losses to a cooling medium circulating within the winding insulation wall

38. Which of the following methods is used for air cooling of turbo-alternators ?

One sided axial ventilation

Two sided axial ventilation

Multiple inlet system

All of the above

Detailed SolutionWhich of the following methods is used for air cooling of turbo-alternators ?

39. The cold rolled grain oriented steel has ______ permeability in the direction of the grain orientation.

minimum

maximum

nil

none of the above

Detailed SolutionThe cold rolled grain oriented steel has ______ permeability in the direction of the grain orientation.

40. The weight of copper of both armature and field windings decreases with _____ in number of poles.

increase

decrease

either of the above

none of the above

Detailed SolutionThe weight of copper of both armature and field windings decreases with _____ in number of poles.

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