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

What is corporate social responsibility, (a) The term "financial reporting"...

(a) The term "financial reporting" incorporates not only financial statements, but also includes other means of communicating financial and non-financial information. Financial rep

Breaks in specific cost of capital, Breaks in Specific Cost of Capital: Th...

Breaks in Specific Cost of Capital: The specific costs of capital may also be affected by the amount of finance the firm wants to raise. As the amount of financing increases, the

Explain the structure of main financial statement, Citilink has just comple...

Citilink has just completed its 2010/11 management accounts. The directors are going to review the financial statements in the next board meeting. You have to prepare a FINANCIAL

Waht are additional information required in chromex plc, Additional informa...

Additional information required Specification of a time scale for the evaluation. Predict cash flow details year by year for period specified in the time scale. An approxima

Defne iu.s. companies that benefit from a stronger dollar, What kinds of U....

What kinds of U.S. companies would benefit most from a stronger dollar in the foreign exchange market?  Explain. U.S. companies which import goods from other countries would bene

Accounting framework - convention of consistency, Accounting Framework  - ...

Accounting Framework  - Convention of Consistency This doctrine denotes that accounting rules, practices & conventions should be continuously observed and applied that implies

Display the position explicitly, Q. Display the position explicitly Ex...

Q. Display the position explicitly Example: I borrow 7800000 HKD at time t = t 0 at an interest rate r t0 . After one year I pay back 7800000(1 + rt o ). At

What is the basic approach of the financial management, Q. What is the basi...

Q. What is the basic Approach of the financial management ? 1) The first approach view finance as to providing the funds needed by a business on the most suitable terms. This ap

Lookback options, Can you describe what the payoffs from lookback options d...

Can you describe what the payoffs from lookback options depend on? Can you write in a concise notation the payoff of a floating lookback call? a. What is the payoff of a portfol

Factors considered in assigning a credit rating, Credit rating agenci...

Credit rating agencies carry out credit rating. Companies appoint these agencies to assign credit rating for their corporate issues. The rating agencies may condu

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