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

Yield, Yield Yield represents the actual return on the investments. Dif...

Yield Yield represents the actual return on the investments. Different types of yield are discussed below: Coupon Yield: The fixed interest rate on a government security or

Meaning of working capital, Problem 1 What are the characteristics of s...

Problem 1 What are the characteristics of small business? Describe the various forms of organisation under which small business operate. Characteristics List the vari

State the economic conditions of cost of capital, State the economic condit...

State the economic conditions of cost of capital General economic conditions These include demand for and supply of capital within the economy and level of expected inflatio

Regulation of mergers and acquisitions, Regulation of Mergers and acquisiti...

Regulation of Mergers and acquisitions Mergers and acquisitions are regulated by: Competition commission If office of fair trading thinks that merg

Evaluate the extent to which the balanced scorecard, Evaluate the extent to...

Evaluate the extent to which the Balanced Scorecard: The Balanced Scorecard has been described as an effective measurement system which enables managers of an organisation to

Cash flow estimation and risk ananlysis.., as a financial analyst, you must...

as a financial analyst, you must evaluate a proposed project to produce printer ink. the equipment would cost 60000 plus 10000 for installation. annual sales would be 5000 units at

Standard deviation for every project, AOT limited is considering two mutual...

AOT limited is considering two mutually exclusive projects - cable and satellite.  The possible NPVs for every project and their associated probabilities are as follows: Cable:

Savage friedman, Question: (a) Describe the axioms of utility. (b) An eco...

Question: (a) Describe the axioms of utility. (b) An economic agent has a logarithmic utility function, U(W) = lnw and has initial wealth $20,000. She is offered the subsequent g

#title.OPERATING CYCLE, DISCUSS THE APPLICABILITY OF OPERATING CYCLE IN VEG...

DISCUSS THE APPLICABILITY OF OPERATING CYCLE IN VEGETABLE GROWING.

Put option, Put Option This is a right which is granted in exchange for...

Put Option This is a right which is granted in exchange for an agreed-upon sum to sell property. Options are mostly used frequently in securities transactions it also used stoc

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