| 1. | Buchhalz's relay is used in ? | |
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motor protection
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line protection
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generator protection
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transformer protection
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Report Question| 2. | Transformer cores are built-up from laminations , rather than from solid metal so that ? | |
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less insulation is required for the windings
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oil penetrates the core more easily
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turn ratio is higher than voltage ratio
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eddy current loss is reduced
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| 3. | The function of an instrument transformer is to ? | |
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act as an isolating device to protect equipment and operation personnel from high voltages
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act as a radio device to enable the use of standardized low range instruments
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discharge both of the above functions
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discharge none of the above functions
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| 4. | The value of useful flux least depends on ? | |
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load
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magnetomotive force
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voltage
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all of the above
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| 5. | The efficiencies of transformers compared with that of electric motors of the same power are ? | |
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about the same
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much smaller
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much higher
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somewhat smaller
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| 6. | For the parallel operation of single phase transformer it is necessary that they should have ? | |
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same efficiency
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same polarity
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same kVA rating
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same number of turns on the secondary side
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| 7. | An ideal transformer will have maximum efficiency at a load such that ? | |
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copper loss = iron loss
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copper loss < iron loss
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copper loss > iron loss I
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none of the above
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| 8. | Star/star transformers work satisfactorily when ? | |
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load is unbalanced only
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load is balanced only
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on balanced as well as unbalanced loads
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none of the above
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| 9. | Transformer breaths in when ? | |
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load on it increases
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load on it decreases
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load remains constant
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none of the above
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| 10. | The purpose of providing iron core in a step-up transformer is ? | |
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to provide coupling between primary and secondary
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to increase the magnitude of mutual flux
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to decrease the magnitude of magnetizing current
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to provide all above features
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