Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
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°.
Question 1: (i) How are education and economic growth connected? (ii) Explain how the export promotion trade strategy may be more growth promoting for developing economies,
Explain what a bond is and discuss its nature as a "fixed income" security.Discuss important terms in relation to bonds as the "price", "maturity", "current yield", "yield to matu
The NPV decision rule needs that a company invest in all projects that have a positive net present value. This presumes that sufficient funds are available for all incremental proj
(a) Lonesome Gulch Mines has a standard deviation of 42% per year and a beta of 0.10. Amalgamated Copper has a standard deviation of 31% a year and a beta of 0.66.
#questThe managing directors of three profitable listed companies discussed their companies'' dividend policies at a business lunch. Company A; has deliberately paid no dividends
Typically, there exist two types of bids in the treasury auction process. They are: Competitive bid and non-competitive bid. A non-competitiv
What is the fastest way to be rich?
What are the Market conditions of cost of capital Security may not be readily marketable when investor wants to sell; or even if a continuous demand for security does exist, p
Significant Performance Indicators Following are the most commonly used performance indicators used to assess the financial, and general health of any company: Gro
(i) No External Financing: - Walter' model presume that the firm's investment are financed exclusively by retained earnings and no external financing is used. If it was therefore t
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!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd