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

Call-put parity, Call-Put Parity P + S = C + E * [1/(1+i)] ^n     where...

Call-Put Parity P + S = C + E * [1/(1+i)] ^n     where:      P = the market price of the put    S = the market price of the stock    C = the market price of the call

Symmetric cash matching, We have earlier studied that the investor ma...

We have earlier studied that the investor may have to carry cash for some time because of discrepancies arising between the timing of the bond's cash-flow and the

Treasury bills in international markets, Treasury Bills in International Ma...

Treasury Bills in International Markets A brief discussion on treasury bills in international markets is given below: Primary Market T-bills are important money market

Computation of working capital, Will you please define the working capital ...

Will you please define the working capital and Calculation of working capital? I need urgent help in my assignment. help me!

What do you mean by misappropriation of fund, Q. What do you mean by Misapp...

Q. What do you mean by Misappropriation Of Fund? Misappropriation Of Funds allotted for specific works under capital or Revenue demand but the expenditure is incurred for anoth

Electronic communications networks, Electronic Communications Networks: ...

Electronic Communications Networks: In traditional stock exchanges, the buying and selling of stocks take place at a physical location only and the members have to conduct tradi

Discount Pricing, Discount Pricing The T-bills are issued at a discount...

Discount Pricing The T-bills are issued at a discount to face value and hence have no coupon. Commission rates on round lots generally range from $12.50 to $25.00 per $1 mil

Role of financial intermediaries in the financial system, Role of Financial...

Role of Financial Intermediaries in the financial system: Having designed the instrument, the issuer should then ensure that these financial assets reach the ultimate investor

State the factors of tests of controls, State the factors of Tests of contr...

State the factors of Tests of controls Tests of controls may include · Enquiries and observations corroborating internal control functions. Inspection of docu

Margin and marking to market, The collaterals used in the repo market...

The collaterals used in the repo market are high quality securities; but they are also not free from credit risk. In our earlier example, we see the dealer borrow

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