MCQOPTIONS
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MCQOPTIONS
This section includes 9 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. |
IF_‚ÂÀ√¨‚ÀÖ√∫M_IS_THE_MAXIMUM_VALUE_OF_FLUX_DUE_TO_ANY_ONE_PHASE,_THEN_RESULTANT_FLUX_IN_2_PHASE_AND_3_PHASE_AC_MACHINES_WOULD_RESPECTIVELY_BE_GIVEN_BY__________?$# |
| A. | φ<sub>m</sub> and 1.5φ<sub>m</sub>, both rotating |
| B. | φ<sub>m</sub> and 1.5φ<sub>m</sub>, both stand still |
| C. | φ<sub>m</sub> stand still and 1.5φ<sub>m</sub> rotating |
| D. | 1.5φ<sub>m</sub> and 2φ<sub>m</sub>, both rotating |
| Answer» B. ‚âà√¨‚àö√∫<sub>m</sub> and 1.5‚âà√¨‚àö√∫<sub>m</sub>, both stand still | |
| 2. |
In case of the 3 phase winding with delta or star connection without neutral, if one of the supply lines gets disconnected, then the MMF becomes _________? |
| A. | Stationary and pulsating |
| B. | Rotating with synchronous speed |
| C. | Rotating with sub synchronous speed |
| D. | Rotating with super synchronous speed |
| Answer» B. Rotating with synchronous speed | |
| 3. |
A 3 phase star connected winding is fed from symmetrical 3 phase supply with their neutrals connected together. If one of the 3 supply lines gets disconnected, then the revolving MMF wave will have a ___________ |
| A. | Constant amplitude but sub synchronous speed |
| B. | Varying amplitude but synchronous speed |
| C. | Constant amplitude but super synchronous speed |
| D. | Varying speed and a speed fluctuating around the synchronous speed |
| Answer» E. | |
| 4. |
The rotating MMF wave of constant amplitude can be produced, only if the time angle displacement between currents is _____________ |
| A. | Less than the space angle displacement between winding axis |
| B. | More than the space angle displacement between winding axis |
| C. | Equal to the space angle displacement between winding axis |
| D. | Any of the mentioned |
| Answer» D. Any of the mentioned | |
| 5. |
Three phase voltages are applied to the three windings of an electrical machine. If any two supply terminals are interchanged, then the rotating MMF wave _____________ |
| A. | Direction reverses, amplitude alters |
| B. | Direction reverses, amplitude unaltered |
| C. | Direction remains same, amplitude alters |
| D. | Direction remains same, amplitude unaltered |
| Answer» C. Direction remains same, amplitude alters | |
| 6. |
What does the space angle α in the equation Fr(α,t)=3/2Fmcos(α-ωt) for MMF produced when 3-phase balanced windings excited by three phase balanced currents represent?$ |
| A. | MMF wave at any moment is sinusoidally distributed in space |
| B. | Entire MMF waveform is travelling at (constant angular speed) synchronous speed |
| C. | MMF wave is of constant amplitude |
| D. | None of the mentioned |
| Answer» B. Entire MMF waveform is travelling at (constant angular speed) synchronous speed | |
| 7. |
When a single-phase winding is excited by an alternating current, then which of the following statements are correct? |
| A. | It produces one stationary MMF wave |
| B. | Produced MMF wave pulsates along its magnetic axis |
| C. | It doesn’t produce two counter rotating MMF wave |
| D. | All of the mentioned |
| Answer» E. | |
| 8. |
Which of the following harmonics are present in the resultant MMF produced by 3 phase currents flowing in the 3 phase windings? |
| A. | Triplen harmonics (3K), where K is an integer |
| B. | 6K+1 harmonics only, where K is an integer |
| C. | 6K-1 harmonics only, where K is an integer |
| D. | 6k+1 and 6K-1 harmonics, where K is an integer |
| Answer» E. | |
| 9. |
If F1 is the constant amplitude of fundamental rotating MMF wave, the for the space harmonics of order 6K-1 (where K=1,2,3….), the harmonic MMF wave is of _____________ |
| A. | Constant amplitude and stationary in space |
| B. | Constant amplitude and rotates along F<sub>1</sub> |
| C. | Varying amplitude and rotates along F<sub>1</sub> |
| D. | Constant amplitude and rotates against F<sub>1</sub> |
| Answer» C. Varying amplitude and rotates along F<sub>1</sub> | |