Electrical Machines Objective Questions
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Armature coil is short circuited by brushes when it lies
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The rapid wear of brushes takes place due to
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If the armature electric current is increased to double its previous value, and the time of commutation is halved, how will the reactance voltage vary?
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In a DC generator sparking between brushes and commutator surface may be due to
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The commutator segments are connected to the armature conductors by means of
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To have sparkless commutation, the armature reaction effect in a DC machine is neutralized by
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In a DC generator, the armature reaction results in
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Iron losses in a DC machine are independent of variation in
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Sparkless commutation can be achieved by employing
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The terminal voltage of a DC shunt generator drops on load because of all of the following reasons except
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In a DC generator the actual flux distribution depends upon
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In DC generators, the cause of rapid brush wear may be
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Current in a coil undergoing commutation is not able to get reversed completely by the end of commutation period. It is due to
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Commutation in a DC machine may be explained as a process
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The change in speed of a DC generator due to increased load is corrected by
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The demagnetising component of armature reaction in a DC generator
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Armature reaction of an unsaturated DC machine is
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A Dc generator can be considered as
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Number of tappings for each equalizer ring is equal to
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Satisfactory commutation of DC machine requires
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Compensating windings are used in DC generators
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In a DC generator in order to reduce sparking at brushes, the self-induced emf in the coil is neutralized by all of the following except
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Which of following components of a DC generator plays vital role for providing direct electric current of a DC generator?
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In a DC generator the ripples in the direct emf generated are reduced by
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The self induced emf in the coil undergoing commutation is called the
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In a DC shunt generator working on load, the brushes are moved forward in the direction of rotation, as a result of this, commutation will
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In a DC generator in case the brushes are moved so as to bring them in magnetic neutral axis, then, there will be
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To achieve spark less commutation brushes of DC generator are rocked ahead so as to bring them
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Under commutation results in
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The voltage drop for which of the following types of brush can be expected to be least ?
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