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With respect to cylindrical rotor alternator explain what is meant by effective
resistance of the armature.
Can the alternators have the fixed field system and rotating armature? Why?
Explain the reasons why the harmonics are introduced into the generated emf
of an alternator. Also explain how these harmonics can be minimized.
Explain how the slot harmonics are introduced in to the generated emf of an
alternator.
What are the different types of windings employed in alternators?
Discuss the effect of harmonics on the generated emf of an alternator.
Explain Blondel’s two reaction theory for salient pole synchronous machine.
Explain how synchronizing power is developed in an alternator. Derive an
expression for the synchronizing power.
Explain hunting as applied to synchronous motor. How it can be reduced?
Explain how the direct and quadrature axis synchronous reactances are
determined?
List the advantages of having rotating field system in alternators.
Derive an expression for the power angle equation of salient pole alternator
connected to an infinite bus bar.
Explain with vector diagrams and excitation characteristics the operation of
synchronous motor at constant power and variable excitation. Explain the
industrial application of this operation.
Derive the expressions for pitch and distribution factors.
What are the conditions that are to be satisfied before connecting a three phase
alternator to a three phase bus bars for parallel operation. Explain any one
method of synchronizing of alternators.
Explain why a synchronous motor is not self starting.
Draw the vector diagram for a cylindrical rotor alternator under
Explain the parallel operation of synchronous generators and load sharing
when two generators are connected in parallel.
What is reluctance power? What is its significance? Explain.
Show that an over excited synchronous machine has higher synchronous
power than that of an under excited one.
Derive an expression for the maximum power received by the synchronous
motor when it is connected to an infinite bus bar.
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22. Using Two reaction theory of salient pole synchronous generators with usual
notations show that the real and reactive power developed can be given by
23. Assume that a round rotor synchronous machine is running at synchronous
speed. The field current is constant. The stator currents of all the phases are
given by
I R = I cos ωt; I Y = I cos (ωt -120); I B = I cos (ωt+120) and
field current = I f , show that the torque developed can be given by
where M is the mutual inductance between the between rotor and stator per
phase, δ i is the torque angle.
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