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

Volume of issues of central and state government securities, Volume of Issu...

Volume of Issues of Central and State Government Securities The growth of government securities market in India and the investor response to the government bond issues can be k

Calculate the economic order quantity, Q. Calculate the Economic Order Quan...

Q. Calculate the Economic Order Quantity? Calculate the Economic Order Quantity from the following details: Annual Inventory Requirements = 4, 00,000 units Cost of placin

State about the manufacturing overseas, State about the Manufacturing overs...

State about the Manufacturing overseas or exporting Dyson (appliances manufacturer) relocated UK production to Malaysia in 2002 though still retained its head office within the

Why is the replacement value of assets method, Why is the replacement value...

Why is the replacement value of assets method not generally used to value complete businesses? The replacement value of assets method isn't often applied to entire business val

Short-term volatility position, (a) The position of an agency that sells a ...

(a) The position of an agency that sells a callable coupon bond. We supposed that coupon bond has a maturity of 3 years and is callable only at the second year. (b) The market t

Working capital financing plan for company implementation, What is the most...

What is the most conservative type of working capital financing plan a company could implement?  Explain. An all equity capital structure would be the mainly conservative type

Calculate the compound return, a)  What two legal documents should the coup...

a)  What two legal documents should the couple ensure are up-to-date if they want a sound estate plan?  What would happen if either became incapacitated or died and didn't have any

Calculate the waac, Question 1: You hold a diversified portfolio consi...

Question 1: You hold a diversified portfolio consisting of a Rs.5,000 investment in each of 20 different common stocks. The portfolio beta is equal to 1.15. You have decided t

Valuation using forward rates, We can discount cash flows either by u...

We can discount cash flows either by using spot rates or forward rates, because a spot rate is simply a package of short-term forward rates. Assume that the cash

The safety margin, Norfolk Ltd is specialized in producing & selling air co...

Norfolk Ltd is specialized in producing & selling air conditions.  In 2010, the manufacturing cost per unit included:

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