Chat with AIExam 12: Alternating-Current Generators
AC generators are also known as ____________________ because they supply electrical energy with an alternating voltage.
(36) 
Verifiedalternators
Explain the effect of lagging power factor.
(24) VerifiedWhen an alternator operates with a lagging power factor, a magnetomotive force (mmf) is set up by the current in the armature conductors. This magnetizing force opposes the magnetomotive force of the main field and causes a decrease in the main field flux. As a result, there is a decrease in the induced voltage. The lower the value of the lagging power factor, the greater is the armature mmf that opposes and weakens the field. For the few applications where an alternator supplies a load with a leading power factor, the armature current sets up an mmf in the armature. This force aids the mmf of the main field so that the main field flux increases. The voltage of the alternator increases with an increase in the load current. The lower the value of the leading power factor, the greater is the armature mmf. This force aids the mmf of the main field, resulting in an increase in the main field flux.
How is the division of the load between dc generators obtained?
(45) VerifiedThe division of the load between dc generators is obtained by changing the field excitation of each generator until the load is shared.
The arithmetic sum of the two alternator currents equals the total current supplied to the load.
(37) The capacity of an alternator is given in kilowatts rather than kilovolt-amperes.
(30) In an AC generator, the direct voltage induced in the armature conductors is changed to an alternating voltage at the brushes by means of the commutator.
(43) ____________________ causes the current to surge back and forth between alternators operating in parallel.
(36) All of the coils of one single-phase winding are collectively known as a(n) ____________________.
(37) Alternators operating in parallel in various central stations often will operate in a network power system.
(27) Why is the practice of operating several alternators in parallel preferred by power-generating stations?
(36) A(n) ____________________ is a single-phase instrument that indicates synchronism accurately.
(42) A(n) ____________________ is generated in stationary armature conductors when the field poles rotate past the conductors.
(35) 
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