MCQOPTIONS
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MCQOPTIONS
This section includes 10 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Machines knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
In a DC machine, z, p, Ia and a are respectively the number of conductors, number of poles, armature current and number of parallel paths. The peak value of fundamental component of armature MMF wave is ____________ |
| A. | 8/ [(z/2p)(I<sub>a</sub>/a)] |
| B. | 8/ <sup>2</sup>[(z/p)(I<sub>a</sub>/a)] |
| C. | 4/ [(z/2p)(I<sub>a</sub>/a)] |
| D. | 8/ <sup>2</sup>[(z/p)(I<sub>a</sub>/a)] |
| Answer» E. | |
| 2. |
A sinusoidal current sheet in a rotating electrical machine has peak value along q-axis. The peak value of sinusoidal MMF would be ___________ |
| A. | in phase with current peak |
| B. | 90 lagging the current peak |
| C. | 90 leading the current peak |
| D. | may lag or lead depending upon the type of machine |
| Answer» D. may lag or lead depending upon the type of machine | |
| 3. |
A winding of 20 full pitched series turns, distributed over a band of 60 under each pole, carries a current of 3A. The winding produces a uniform current sheet of density (in AT s per electrical radiangs) of ___________ |
| A. | 180/ |
| B. | 120/ |
| C. | 90/ |
| D. | 60/ |
| Answer» B. 120/ | |
| 4. |
MMF produced by one N-turn coil carrying a current i is ____________ |
| A. | rectangular of amplitude Ni/2 |
| B. | trapezoidal of amplitude Ni/2 |
| C. | rectangular of amplitude Ni |
| D. | trapezoidal of amplitude Ni |
| Answer» B. trapezoidal of amplitude Ni/2 | |
| 5. |
A uniformly distributed winding on the stator has three full pitched coils, each coil having N turns and each turn carrying a current i. The MMF produced by the winding is? |
| A. | sinusoidal in waveform with an amplitude 3Ni |
| B. | sinusoidal in waveform with an amplitude 3Ni/2 |
| C. | trapezoidal in waveform with an amplitude of 3Ni |
| D. | trapezoidal in waveform with an amplitude of 3Ni/2 |
| Answer» E. | |
| 6. |
Peak value of fundamental component of MMF produced by one N-turn coil carrying a current i is ____________ |
| A. | 4/ (Ni) |
| B. | 2/ (Ni) |
| C. | 1/ (Ni) |
| D. | 1/2 (Ni) |
| Answer» C. 1/ (Ni) | |
| 7. |
If the current in a coil is AC, the amplitude of MMF ___________ |
| A. | varies with time but not with space |
| B. | varies with space but not with time |
| C. | varies with both space and time |
| D. | doesn t vary with both space and time |
| Answer» B. varies with space but not with time | |
| 8. |
If the current in the coil is DC, then MMF doesn t vary with ____________ |
| A. | space |
| B. | time |
| C. | both space and time |
| D. | none of the mentioned |
| Answer» D. none of the mentioned | |
| 9. |
A knowledge of the air gap flux distribution in a machine helps in determining the ___________ |
| A. | generated EMF waveform and its magnitude |
| B. | electrical torque |
| C. | winding MMF |
| D. | both generated EMF waveform and electrical torque |
| Answer» E. | |
| 10. |
The winding MMF in rotating machines depends on ___________ |
| A. | winding arrangement |
| B. | winding current |
| C. | air gap length,slot openings etc |
| D. | both winding arrangement and winding current |
| Answer» E. | |