Electrical Machines Questions and Answers – Synchronous Machines
EMF Polygon – 1
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Consider the following statements regarding the design of distributed armature winding in a 3phase alternator:
(i) it reduces the phasebelt harmonics
(ii) it increases the utilization of the armature iron and copper
(iii) it increases rigidity and mechanical strength of the winding
(iv) it reduces copper in the overhang of the winding
Which of these statements are correct?
(i) it reduces the phasebelt harmonics
(ii) it increases the utilization of the armature iron and copper
(iii) it increases rigidity and mechanical strength of the winding
(iv) it reduces copper in the overhang of the winding
Which of these statements are correct?
Correct!
Wrong!

The pitch factor, in rotating electrical machinery, is defined as the ratio of resultant EMF of a
Correct!
Wrong!

What is the coil span for a 2 pole 18 slot machine?
Correct!
Wrong!

If a stator has 48 slots, 6 poles and 3 phase with narrow spread winding, then the third harmonic belt factor is _______
Correct!
Wrong!

The belt factor is defined as the ratio of
Correct!
Wrong!

1. The angular slot pitch, γ is given by
Correct!
Wrong!

A fraction pitch winding is used to reduce
(i) amount of copper in the winding
(ii) size of the machine
(iii) harmonics in the generated EMF
(iv) cost of the machine
From these, the correct answer is
(i) amount of copper in the winding
(ii) size of the machine
(iii) harmonics in the generated EMF
(iv) cost of the machine
From these, the correct answer is
Correct!
Wrong!

In a machine with coil span 9, if a coil has its one coilside in slot 1, then its other coilside must be in ____________
Correct!
Wrong!

A 3phase machine has integral slot winding with fundamental distribution factor k_{d}_{1}, the distribution factor for nth harmonic k_{d}_{n} is ____________
Correct!
Wrong!

The armature winding of a 2pole, 3phase alternator for each phase is distributed in a number of slots per phase. The RMS value of the voltage per phase is less than the RMS value of the voltage per coil multiplied by the number of coils in series because the
Correct!
Wrong!
