Power Generator

41. Cumulatively compounded motors are used in applications where ___________ is required

1. variable speed
2. poor speed regulation
3. sudden heavy loads for a short duration
4. constant speed

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42. Damper windings are used in alternators to

1. prevent hunting
2. achieve synchronism
3. reduce wind age losses
4. reduce eddy current loss

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43. DC machines which are subjected to abrupt changes of load are provided with

1. interpole windings
2. compensating winding
3. equalizers
4. copper brushes

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44. DC series motors are used in those applications where ___________ required

1. high starting torque
2. low no load speed
3. constant speed
4. variable speed

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45. DC shunt motors are used in those applications where ___________ is required

1. high starting torque
2. high no load speed
3. practically constant speed
4. variable speed

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46. Difference between the speed of a rotating magnetic field and the associated rotor

1. split
2. salient pole
3. slip
4. pull out torque

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47. Excessive motor vibration is caused by

1. too much brush tension
2. open armature coil
3. worn bearings
4. bent shaft

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48. Excessive sparking at the brushes may caused due to

1. dirt on the commutator
2. misalignment of machine
3. loose coupling
4. worn bearings

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49. For 20% increase in current, the motor that will give the greatest increase in ___________ torque is motor

1. shunt
2. series
3. differentially compounded
4. commulatively compounded

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50. For a given dc generator, the generated voltage depends upon

1. flux only
2. both speed and flux
3. speed only
4. armature rotation

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