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

Define the process of wealth maximisation, Define the process of Wealth Max...

Define the process of Wealth Maximisation Shareholders' wealth can be defined as total market value of all the equity shares of company. So when we talk about maximising wealth

Describe the types of financial ratios, 1. Describe the types of financial ...

1. Describe the types of financial ratios and other financial performance measures that are used during a venture's successful life cycle. Who are the users of financial performan

Explain the methods used to treat the obsolete stock, Explain the methods u...

Explain the methods used to treat the obsolete stock Review Inventory for obsolete items Make materials review board Include an obsolescence review in the closing p

Features of capital budgeting decisions, Features of Capital Budgeting Deci...

Features of Capital Budgeting Decisions 1.       Existence of potentially large anticipated profits. 2.       Involves a comparatively high degree of risk 3.       Exist

State the significance of the cost of capital, State the Significance of th...

State the Significance of the Cost of Capital It must be recognized at the outset that cost of capital is one of the most difficult and disputed topics in the finance theory.

Which ratios would a banker be most interested, Which ratios would a banker...

Which ratios would a banker be most interested in when considering whether to approve an application for a short-term business loan? Explain. Bankers and other lenders use liq

Capital budgeting, #how to calculate initial investment cash flows ..

#how to calculate initial investment cash flows ..

Surplus economic unit deal with a deficit economic unit, What can a financi...

What can a financial institution often do for a surplus economic unit that it would have difficulty doing for itself if the surplus economic unit (SEU) were to deal directly with a

Conversion value, Conversion value is the amount which investors wi...

Conversion value is the amount which investors will receive by immediately exchanging the bonds for equity stock and selling the stock at prevailing market

Define the term- cash purchases, Define the term- Cash purchases     Shar...

Define the term- Cash purchases     Shareholders of the target company are bought out completely and have no further stake in business. This is good if predator shareholders want

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