Synchronous motors Archives

41. The magnitude of field flux in a 3-phase synchronous motor

remains constant at all loads

varies with speed

varies with the load

varies with power factor

Detailed

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Solution

42. If the field winding of an unloaded salient pole synchronous motor is open circuited, the motor will

stop

run as induction motor

function as static condenser

burn with dense smoke

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an unloaded salient pole synchronous motor is open circuited, the motor will" class="read-more button" href="https://exam.pscnotes.com/mcq/if-the-field-winding-of-an-unloaded-salient-pole-synchronous-motor-is-open-circuited-the-motor-will/#more-52613">Detailed Solution

43. A synchronous motor is running on a load with normal excitation. Now if the load on the motor is increased

power factor as well as armature current will decrease

power factor as well as armature current will increase

power factor will increase but armature current will decrease

power factor will decrease and armature current will increase

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44. A synchronous motor running with normal excitation adjusts to load increases essentially by increase in

back e.m.f.

armature current

power factor

torque angle

Detailed SolutionA synchronous

motor running with normal excitation adjusts to load increases essentially by increase in

45. Stability of a synchronous machine

decreases with increase in its excitation

increases with increase in its excitation

remains unaffected with increase in excitation

any of the above

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46. The effect of increasing the load on a synchronous motor running with normal excitation is to

decrease both armature current and power factor

decrease armature current but increase power factor

increase armature current but decrease power factor

increase both its armature current and power factor

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href="https://exam.pscnotes.com/mcq/the-effect-of-increasing-the-load-on-a-synchronous-motor-running-with-normal-excitation-is-to/#more-52180">Detailed Solution

47. The net armature voltage of a synchronous motor is equal to the

vector sum of Eb and V

arithmetic sum of Eb and V

arithmetic difference of Eb and V

vector difference of Eh and V

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48. In a synchronous motor, the magnitude of stator back e.m.f. (Eb) depends on

d.c. excitation only

speed of the motor

load on the motor

both the speed and rotor flux

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viewBox="0 0 576 512"> Subscribe on YouTube e.m.f. (Eb) depends on" class="read-more button" href="https://exam.pscnotes.com/mcq/in-a-synchronous-motor-the-magnitude-of-stator-back-e-m-f-eb-depends-on-2/#more-51726">Detailed Solution