8 One phase of a 3-phase alternator consists of twelve coils in series. Each coil has an rm.s. voltage of 10 V induced in it and the coils are arranged in slots so that there is a successive phase displacement of 10 clectrical degrees between the e.m.f. in each coil and the next. Find graphically or by calculation, the E.M.S, value of the total phase voltage developed by the winding. If the alternator has six pole and is driven at 100rp.m., calculate the frequency of the e.m.f. generated I 108 V: 50 Ha)

8 One phase of a 3-phase alternator consists of twelve coils in series. Each coil has an rm.s. voltage of 10 V induced in it and the coils are arranged in slots so that there is a successive phase displacement of 10 clectrical degrees between the e.m.f. in each coil and the next. Find graphically or by calculation, the E.M.S, value of the total phase voltage developed by the winding. If the alternator has six pole and is driven at 100rp.m., calculate the frequency of the e.m.f. generated I 108 V: 50 Ha)

Delmar's Standard Textbook Of Electricity

7th Edition

ISBN:9781337900348

Author:Stephen L. Herman

Publisher:Stephen L. Herman

Chapter31: Three-phase Alternators

Section: Chapter Questions

Problem 1RQ: What conditions must be met before two alternators can be paralleled together?

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What conditions must be met before two alternators can be paralleled together?
8. One phase of a 3-phase alternator consists of twelve coils in series. Each coil has an r.m.s. voltage of 10 V induced in it and the coils are arranged in slots so that there is a successive phase displacement of 10 electrical degrees between the e.m.f. in each coil and the next. Find graphically or by calculation, the r.m.s. value of the total phase voltage developed by the winding. If the alternator has six pole and is driven at 100 r.p.m., calculate the frequency of the e.m.f. generated. [108 V; 50 Hz] 9. A 4-pole, 50-Hz, 3-phase, Y-connected alternator has a single-layer, full-pitch winding with 21 slots per pole and two conductors per slot. The fundamental flux is 0.6 Wb and air-gap flux contains a third harmonic of 5% amplitude. Find the r.m.s. values of the phase e.m.f. due to the fundamental and the 3rd harmonic flux and the total induced e.m.f. [3,550 V; 119.5 V; 3,553 V] (Elect. Machines-III, Osmania Univ. 1977)
v. With reference to an 50 Hz3 phase alternator explain how P,Q,V and F are controlled.
Q5: A 3-phase, 50 Hz, 8-pole alternator has a star-connected winding with 120 slots and 8 conductors per slot.The flux per pole is 0.05 Wb, sinusoidally distributed. Determine the phase and line voltages.
3. One phase of a 3-phase alternator consist of 12 coils in series. Each coil has an rms voltage of 10V induced in it and the coils are arranged in slots so that there is a successive phase displacement of 10 electrical degrees between the emf in each coil an the next. Find by calculation the rms value of the total phase voltage developed by the winding. If the alternator has six pole and is driven at 100 rpm.
Q1/ Caleulate the voltage per phase for a 3-phase 1500 rpm, 4-pole alternator having a 16 conductors per slot connected in two layers. The slots per pole per phase are 8 and the coil span is 20 slots. The phase spread is 60° and the flux per pole is 25-8 x 10 weber.
ALTERNATOR (AC GENERATOR) 1. A part of an alternator winding consist of six coil in series, each coil having an e.m.f. of 10 v (r.m.s.) induced in it. The coils are placed in successive slots and between each slot and the next, there is an electrical phase displacement of 30°. Find the e.m.f. of the six coils in series.
7. A 3-phase, Y-connected, 2-pole alternator runs at 3,600 r.p.m. If there are 500 conductors per phase in series on the armature winding and the sinusoidal flux per pole is 0.1 Wb, calculate the magnitude and frequency of the generated voltage from first principles. 8. One phase of a 3-phase alternator consists of twelve coils in series. Each coil has an r.m.s. voltage of 10 V induced in it and the coils are arranged in slots so that there is a successive phase displacement of 10 electrical degrees between the e.m.f. in each coil and the next. Find graphically or by calculation, the r.m.s. value of the total phase voltage developed by the winding. If the alternator has six pole and is driven at 100 r.p.m., calculate the frequency of the e.m.f. generated. [60 Hz; 11.5 kV] [ 108 V; 50 Hz]
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Q4 A 11 kV, 500 MVA alternator is connected to a slow C.B. through a bus-bar. Determine the three ratings of the C.B, the average RRRV, and the oscillation frequency knowing that it reaches the peak re-striking voltage with 100 µs time.
The rotating part in an alternator is ................
A three phase, 50 Hz, 8 pole alternator has a star connected winding with 120 slots and 6 conductor per slot. The flux per pole is 0.05 Wb, sinusoidally distributed. Determine the phase and line voltages if the coil is full pitched.