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

Above the line deduction, Above the line deductions are certain kinds of de...

Above the line deductions are certain kinds of deductions that are deducted from your income before the adjusted gross income is computed for tax purposes. Above the line deduct

What is logistics, What is logistics? Explain the important activities in l...

What is logistics? Explain the important activities in logistics systems. Logistics - meaning . Working of logistics systems - three important activities - Order processing, I

What is a hedge fund, Q.What is a Hedge Fund? A Hedge Fund is a fund es...

Q.What is a Hedge Fund? A Hedge Fund is a fund established by one or else several partners with net worth of at least $1 million (although this maybe falling). It uses long as

Double declining balance method , Suppose that the business uses the double...

Suppose that the business uses the double declining balance method to depreciate  its equipment (a)  Determine the net book value, depreciation expense, and accumulated deprecia

Define flotation costs affect cost of raising that capital, When a company ...

When a company issues new securities, how do flotation costs affect the cost of raising that capital? While a company issues new securities flotation costs raise the cost of rais

Calculate the price of winnebago stock , Calculate the price of Winnebago s...

Calculate the price of Winnebago stock (Winnebago has no debt so this is the market value of the firm seperated by the number of common shares outstanding.) from the cashflows you

Compute the income available for equity shares, Evergreen Company Ltd has b...

Evergreen Company Ltd has been promoted by promoters. They are trying to decide how the company could be financed. There are three choices: i. Issue Rs 500,000 in Equity shares

Classification of the cost, 1) Future cost and historical cost: financial ...

1) Future cost and historical cost: financial decision is based on the future cost and not on the historical cost. The decision related to the future and hence the cost are likely

Calculate the standard deviation of a portfolio , Aquaman stock has exhibit...

Aquaman stock has exhibited a standard deviation in returns of 0.7, whereas Green Lantern stock has exhibited a standard deviation of 0.8. The correlation coefficient between the

What are the benefits of collecting early and how it attempt, What are the ...

What are the benefits of "collecting early" and how do companies attempt to do this? A fund has time value.The sooner money is collected the better.  Companies utilize regional

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