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

Principle of calculation of goodwill, This question tested the core area of...

This question tested the core area of specifically gradually consolidation and acquisitions (control to control). The principle of calculation of goodwill at the date where control

Social assistance program for the elderly, Social Assistance Program for th...

Social Assistance Program for the Elderly For the elderly destitutes, the Central and many State Governments have designed several social assistance programs. Under the nationa

Illustrate the term quality of benefits, Illustrate the term quality of ben...

Illustrate the term quality of benefits It is clear from Table that total returns associated with two alternatives are identical in a normal situation but range of variati

What do you mean by utility, Q. What do you mean by Utility? Utility: -...

Q. What do you mean by Utility? Utility: - Financial leverage assists considerably the financial manager while devising the capital structure of the company. A high financial l

Define the meaning of overtrading, Define the meaning of Overtrading Wh...

Define the meaning of Overtrading When  a  company  is  trading  at  a  very  fast  pace,  it  would be  generating  sales  on  credit  with  speed, so have a large volume of t

What are the benefits of holding inventories, Q. What are the Benefits of H...

Q. What are the Benefits of Holding Inventories? (1) Timing of Demand and Supply: - Requirement to hold inventory of raw materials arises because it isn't possible for a firm

Mrs. Edwards, If invested 2500 in a bank that pays 1% annually. How long wi...

If invested 2500 in a bank that pays 1% annually. How long will it take for the funds to double?

Assignmment, what is logical process modelling? what is physical modelling?...

what is logical process modelling? what is physical modelling?

Pension fund management, Pension fund management Pension fund systems o...

Pension fund management Pension fund systems ought to be carefully designed and supervised to make sure that their purposes are met, the economic consequences are appropriate a

Explain the concept of the world beta of a security, Explain the concept of...

Explain the concept of the world beta of a security. Answer:  The world beta calculates the sensitivity of returns to a security to returns to the world market portfolio. It is

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