| 1. | The advantage of salient poles in an alternator is ? | |
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reduced windage loss
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reduced bearing loads and noise
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reduced noise
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adaptability of low and medium speed operation
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Report Question| 2. | Due to which of the following reasons, for aircraft alternators high frequency is used ? | |
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To reduce the bulk
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To compensate for high speeds
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To compensate for high altitudes
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To free the systems from external disturbance
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| 3. | When an alternator is supplying unity power factor load, the armature reaction will produce ? | |
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distortion of the main field
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magnetisation of the main field
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demagnetisation of the main field
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none of the above
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| 4. | ln an alternator, the flux created by the armature m.m.f. subtracts directly from the main flux for the following conditions of the load ? | |
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load power factor is unity
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load power factor is 0.6 lagging
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load power factor is zero lagging
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load power factor is zero leading
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| 5. | Which harmonic will be totally eliminated in an alternator by using a fractional pitch of 4/5 ? | |
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Third
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Fifth
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Seventh
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Ninth
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| 6. | In power generating stations (Thermal stations), The usual number of poles employed in alternators are ? | |
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twenty four
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thirty two
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forty eight
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none of these
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| 7. | An alternator coupled to which prime mover will usually have the highest rotating speed ? | |
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Steam engine
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Reciprocating diesel engine
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Francis turbine
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Steam turbine
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| 8. | The speed of a p-pole synchronous machine in r.p.m. is given by ? | |
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120f/p
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120p/f
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p/?120fp
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120fp
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| 9. | In a synchronous machine, all of the following losses are fixed except ? | |
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core loss
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copper loss
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bearing friction loss
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windage loss
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| 10. | To obtain sinusoidal flux distribution ? | |
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chamfering of poles is done in turbo alternators only
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chamfering of poles is done m salient pole alternators only
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either of the above
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none of the above
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