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_GENERATOR,_THE_COMMUTATOR_SERVES_AS_A__________?$ |
| A. | mechanical rectifier for alternating EMF to direct EMF |
| B. | mechanical inverter to invert the direct applied voltage to alternating voltage |
| C. | any of the mentioned |
| D. | none of the mentioned |
| Answer» B. mechanical inverter to invert the direct applied voltage to alternating voltage | |
| 2. |
In a DC motor, the commutator serves as a ___________$ |
| A. | mechanical rectifier for alternating EMF to direct EMF |
| B. | mechanical inverter to invert the direct applied voltage to alternating voltage |
| C. | any of the mentioned |
| D. | none of the mentioned |
| Answer» C. any of the mentioned | |
| 3. |
In a DC machine, the pole core is usually of smaller cross section than the pole shoe because __________? |
| A. | smaller cross section requires less copper |
| B. | larger pole shoe increases the air gap reluctance |
| C. | larger pole shoe increases the flux per pole entering the armature |
| D. | larger pole shoe reduces the mechanical strength |
| Answer» D. larger pole shoe reduces the mechanical strength | |
| 4. |
In larger DC machines, the reason behind using fabricated steel instead of cast iron in the manufacture of yoke is ? |
| A. | economical considerations |
| B. | permeability considerations |
| C. | mechanical considerations |
| D. | insulation considerations |
| Answer» C. mechanical considerations | |
| 5. |
A synchronous machine can be connected to an energy system only when ___________ |
| A. | frequency/rotational speed matches |
| B. | voltage matches |
| C. | current matches |
| D. | power matches |
| Answer» B. voltage matches | |
| 6. |
In a synchronous generator, the frequency of the generated EMF depends on |
| A. | rotational speed |
| B. | poles |
| C. | both rotational speed and poles |
| D. | none of the mentioned |
| Answer» D. none of the mentioned | |
| 7. |
For relatively large sizes of synchronous machines, which of the following are used for providing closed circuit cooling? |
| A. | air |
| B. | water |
| C. | hydrogen/helium |
| D. | any of the mentioned |
| Answer» E. | |
| 8. |
Commercially, which of the following generators is called turbo-alternators or turbo-generators? |
| A. | salient pole rotor synchronous generators |
| B. | cylindrical pole rotor induction generators |
| C. | salient pole rotor induction generators |
| D. | cylindrical rotor synchronous generators |
| Answer» E. | |
| 9. |
In a synchronous machine, cylindrical pole construction has been found to suit best for ___________ |
| A. | low speed prime movers |
| B. | high speed prime movers |
| C. | medium speed prime movers |
| D. | any of the mentioned |
| Answer» C. medium speed prime movers | |
| 10. |
How many poles should the alternators, driven by the steam and gas turbines prime movers must have, for better operation? |
| A. | fewer number of poles |
| B. | large number of poles |
| C. | medium number of poles |
| D. | any of the mentioned |
| Answer» B. large number of poles | |