Explain balanced wye-connected load, Electrical Engineering

Assignment Help:

Balanced Wye-Connected Load

Let us consider a three-phase, four-wire 208-V supply system connected to a balanced wye connected load with an impedance of 10 20° , as shown in Figure (a). We shall solve for the line currents and draw the corresponding phasor diagram.

Conventionally it is assumed that 208 V is the rms value of the line-to-line voltage of the supply system, and the phase sequence is positive, or A-B-C, unless mentioned otherwise. The magnitude of the line-to-neutral (or phase) voltages is given by 208/√3, or 120 V. Selecting the line currents returning through the neutral conductor, as shown in Figure, we have

1407_Balanced Wye-Connected Load.png

Note that ¯VBC has been chosen arbitrarily as the reference phasor, as in Figure (b). Assuming the direction of the neutral current toward the load as positive, we obtain

1532_Balanced Wye-Connected Load1.png

That is to say that the system neutral and the star point of the wye-connected load are at the same potential, even if they are not connected together electrically. It makes no difference whether they are interconnected or not.

Thus, for a balanced wye-connected load, the neutral current is always zero. The line currents and phase currents are equal inmagnitude, and the line currents are in phasewith the corresponding phase currents. The line-to-line voltages, in magnitude, are √3 times the phase voltages, and the phase voltages lag the corresponding line voltages by 30°.

The phasor diagram is drawn in Figure(b), from which it can be observed that the balanced line (or phase) currents lag the corresponding line-to-neutral voltages by the impedance

55_Balanced Wye-Connected Load2.png

angle (20° in our example). The load power factor is given by cos 20° for our problem, and it is said to be lagging in this case, as the impedance angle is positive and the phase current lags the corresponding phase voltage by that angle.

The problem can also be solved in a simpler way by making use of a single-line equivalent circuit, as shown in Figure(c),

303_Balanced Wye-Connected Load3.png

in which ¯ VL-N is chosen as the reference for convenience. The magnitude of the line current and the power factor angle are known; the negative sign associated with the angle indicates that the power factor is lagging. By knowing that the line (or phase) currents ¯IA, ¯IB, ¯IC lag their respective voltages ¯VAN, ¯VBN, and ¯VCN by 20°, the phase angles of various voltages and currents, if desired, can be obtained with respect to any chosen reference, such as ¯VBC.


Related Discussions:- Explain balanced wye-connected load

The electrical circuit, Normal 0 false false false EN-U...

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4

Product of two sinsoids, Connect the two signals used in section 2 above to...

Connect the two signals used in section 2 above to the "Multiplier" module. Make sure that you record the amplitude of each signal. Observe and record the resultant waveform in

Obtain an expression for the closed-loop transfer function, Q. A noninverti...

Q. A noninverting op-amp circuit and its closed-loop representation are given in Figure. Obtain an expression for the closed-loop transfer function H(ω) = Y (ω)/X(ω) and comment on

Find the highest speeds at which linkage would be possible, Q. Two coupled ...

Q. Two coupled synchronous machines are used as a motor-generator set to link a 25-Hz system to a 60-Hz system. Find the three highest speeds at which this linkage would be possibl

Control, Ask The goal of this project is to model a system and to design a ...

Ask The goal of this project is to model a system and to design a controller for the system so that the closed-loop system performs satisfactorily. We want to accurately positio

Calculate the gross torque developed for a flux, Q. A four-pole, dc seriesm...

Q. A four-pole, dc seriesmotor has a lap-connected, two-layer armature winding with a total of 400 conductors. Calculate the gross torque developed for a flux per pole of 0.02 Wb a

Define transmission-system efficiency, Q. Define Transmission-system effici...

Q. Define Transmission-system efficiency? The transmission-system ef?ciency is de?ned as the ratio of the real power delivered to the receiving-end bus to the real power transf

N-channel enhancement mosfet, Given an n-channel enhancement MOSFET having ...

Given an n-channel enhancement MOSFET having V T = 4V, K = 0.15 A/V 2 , I DQ = 0.5A, V DSQ = 10 V, and V DD = 20 V. Using the dc design approach outlined in this section, dete

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