Electrical Machines Questions and Answers – Synchronous Machines
EMF Polygon – 2
0%
A 3phase, 4pole alternator has 48 stator slots carrying a 3phase distributed winding. Each coil of the winding is short chorded by one slot pitch. The winding factor is given by ___________
Correct!
Wrong!

Which among the given harmonics are called belt harmonics?
Correct!
Wrong!

A 6pole alternator with 36 slots carries a 2phase distributed winding. Each coil is short pitched by one slot. The winding factor is given by
Correct!
Wrong!

In 48 slot, 4pole,3 phase alternator, the coilspan is 10. Its distribution and pitch factors are respectively ___________
Correct!
Wrong!

The winding’s for a 3phase alternator are:
(i) 36 slots, 4 poles, span 1 to 8
(ii) 72 slots, 6 poles, span 1 to 10
(iii) 96 slots, 4 poles, span 1 to 21
The winding’s having pitch factor of more than 0.97 are
(i) 36 slots, 4 poles, span 1 to 8
(ii) 72 slots, 6 poles, span 1 to 10
(iii) 96 slots, 4 poles, span 1 to 21
The winding’s having pitch factor of more than 0.97 are
Correct!
Wrong!

Machine A has 60° phase spread and machine B has 120° phase spread. Both the machines have uniformly distributed winding. The ratio of distribution factors of machine A to machine B is ___________
Correct!
Wrong!

Consider the following statements:
(i) breadth factor for third harmonic k_{d3} is more than that for fundamental k_{d1}
(ii) k_{d3} < k_{d1}
(iii) k_{d3} may be less or more than k_{d1} depending upon the number of slots and poles
(iv) coilspan factor for third harmonic k_{p3}>k_{p1} (coil span factor for fundamental)
(v) k_{p3} < k_{p1}
(vi) k_{p3} may be less or more than k_{p1} depending upon the number of slots and poles
From these, the correct answer is
(i) breadth factor for third harmonic k_{d3} is more than that for fundamental k_{d1}
(ii) k_{d3} < k_{d1}
(iii) k_{d3} may be less or more than k_{d1} depending upon the number of slots and poles
(iv) coilspan factor for third harmonic k_{p3}>k_{p1} (coil span factor for fundamental)
(v) k_{p3} < k_{p1}
(vi) k_{p3} may be less or more than k_{p1} depending upon the number of slots and poles
From these, the correct answer is
Correct!
Wrong!

The chording angle for eliminating 5th harmonic should be __________
Correct!
Wrong!

For eliminating nth harmonic from the EMF generated in the phase of a 3phase alternator, the chording angle should be
Correct!
Wrong!
