Correct Answer - Option 2 : 1500 to 3000 rpm
Turboalternators:
- High speed alternators are called as Turbo alternators. The range of speed is 1500 to 3000 rpm.
- To provide high speed of rotation, the rotor diameter is reduced, and the axial length is increased
- Two or four poles are normally used in the turbo alternators
- Mostly steam turbines are used as prime movers
- Wrought iron is used for the manufacture of large turbo-alternator
- Cylindrical type rotors are used in turbo alternators and these are made up of solid steel forging to get high mechanical stress
Non-salient pole type or cylindrical type rotors are used in high-speed alternators or turbo-alternators having speed between 1500 rpm to 3000 rpm.
Salient pole rotors are used in low-speed devices, from 100 rpm to 1500 rpm.
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Salient pole rotor
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Cylindrical rotor
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Large diameter and short axial length
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Small diameter and long axial length
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Used for low-speed alternators
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Used for high-speed turbo alternators
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Has projecting poles
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Has no projecting poles
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Needs damper windings
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Do not need damper windings
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Windage loss is more
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Windage loss is less
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