A 3-phase, 8-pole, 60-Hz, star-connected alternator has 96 slots with 10 turns per coil. The coil span is 10 slots. 60o groups, 2-layer winding is used. All coils in a phase are connected in series. (a)Find the total number of coil groups in the machine. (b)Find the total number of coils in the machine, C. (c)Find the number of coils in a coil group, m.
Synchronous Generator
In comparison to an asynchronous generator, it is a machine where the rotor speed is equal to the rotating magnetic field produced by the stator, i.e., mechanical speed is equal to the electrical speed, thus called synchronous, and not asynchronous.
Salient Pole Rotor
Salient pole rotor includes a large number of exposed poles mounted on a magnetic wheel. The construction of a bright pole is as shown in the image on the left. The proposed poles are made of metal laminations. The rotor winding is provided on these poles and is supported by pole shoes.
A 3-phase, 8-pole, 60-Hz, star-connected alternator has 96 slots with 10 turns per coil. The coil span is 10 slots. 60o groups, 2-layer winding is used. All coils in a phase are connected in series.
(a)Find the total number of coil groups in the machine.
(b)Find the total number of coils in the machine, C.
(c)Find the number of coils in a coil group, m.
(d)Find the number of turns per phase, Tph.
(e)Given that the upper side of coil 1 lies in slot 1, find the following slots:
(i) the slot which carries the lower side of coil 1
(ii)the slot which carries the lower side of coil 90
(f)Give the numbers of the following coils:
(i)all coils forming coil group 1 [ i.e. the first group named A] of phase A winding
(ii)all coils forming coil group 2 [ i.e. the first group named A’] of phase A winding
(g)Calculate the distribution and coil span factors.
(i)Calculate the phase voltage on no load, when the air-gap flux per pole is 0.05 Wb.
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