Three-phase source voltages and phase sequence, Financial Management

Assignment Help:

Q. Three-phase source voltages and phase sequence?

The elementary three-phase, two-pole generator shown in Figure has three identical stator coils (aa, bb, and cc) of one or more turns, displaced by 120° in space from each other. The rotor carries a ?eld winding excited by the dc supply through brushes and slip rings. When the rotor is driven at a constant speed, voltages of equal amplitude but different phase angle will be generated in the three phases in accordance with Faraday's law. Each of the three stator coils constitutes one phase of this single generator. If the ?eld structure is so designed that the ?ux is distributed sinusoidally over the poles, the ?ux linking any phase will vary sinusoidally with time, and sinusoidal voltages will be induced in the three phases. These three induced voltage waves will be displaced by 120 electrical degrees in time because the stator phases are displaced by 120° in space. When the rotor is driven counterclockwise, Figure (a) shows the wave forms and Figure (b) depicts the corresponding phasors of the three voltages. The time origin and the reference axis are chosen on the basis of analytical convenience. In a balanced system, all three phase voltages are equal in magnitude but differ from each other in phase by 120°. The sequence of voltages in Figure 4.1.2(b), corresponding to that of Figure (a), is known as the positive sequence (a-b-c). On the other hand, if the rotor is driven clockwise, then Figure (c) shows the corresponding phasor of the three voltages; the sequence of voltages in Figure (c) is known as negative sequence (a-c-b). Notice that in positive sequence ¯Ebb lags ¯Eaa by 120°, and ¯Ecc lags ¯Ebb by 120°; in negative sequence, however, ¯ Ecc lags ¯ Eaa by 120°, and ¯ Ebb lags ¯ Ecc by 120°.

1933_Three-phase source voltages and phase sequence.png


Related Discussions:- Three-phase source voltages and phase sequence

Capital budegting, SCL Limited a highly profitable company is engaged in th...

SCL Limited a highly profitable company is engaged in the manufacture of power intensive products.

Calculate the amount invested in treasury bonds, You have an investment cap...

You have an investment capital of $1,000,000.  You plan to invest a portion of this money in Treasury bonds and the remainder in a stock portfolio.  Treasury bonds are expected to

What is nondiversifiable risk? how is it measured, What is nondiversifiable...

What is nondiversifiable risk? How is it measured? But for the returns of one-half the assets in a portfolio are flawlessly negatively correlated with the other half-which is e

Features of a budget, FEATURES OF A BUDGET a.         It is prepared f...

FEATURES OF A BUDGET a.         It is prepared for a specific period. b.         It is expressed in quantity or money or both. c.         It is a statement describing ob

Variance analysis of budget, Variance Analysis: In its commonest form v...

Variance Analysis: In its commonest form variance analysis is the process of comparing budgeted financial performance (or financial goals) against actual financial performance.

What happens when a bank charges discount interest on a loan, What happens ...

What happens when a bank charges discount interest on a loan? When a bank charges reduction in interest on a loan the required interest payment is subtracted from the loan proc

Floating-rate securities that have adjustable quoted margin, Floaters ...

Floaters that can be classified under this head are: 1. Stepped Spread Floaters 2.  Extendible Reset Bonds

Explain foreign equity ownership restrictions, Explain foreign equity owner...

Explain foreign equity ownership restrictions. Why do you think countries entail these restrictions? Several countries restrict the maximum fractional ownership of local organiza

What are the limitations of ratio analysis, What are the Limitations of rat...

What are the Limitations of ratio analysis A ratio on its own is meaningless. Accounting ratios should always be interpreted in relation to other information, for illustration:

Define variants of basic interest rate and currency swaps, Briefly discuss ...

Briefly discuss some variants of the basic interest rate and currency swaps. Answer:  In place of the basic fixed-for-floating interest rate swap, there are as well zero-coupo

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd