The first try was wrong as shown (part A) Part B Show that the sum of the three

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The first try was wrong as shown (part A)

Part B Show that the sum of the three phases is zero, producing what is referred to as neutral. In single-phase electricity, provided by the familiar 120 V/60 Hz electric outlets in your home. one side of the outlet is neutral, as established at a nearby electrical substation. The other, called the hot side, is one of the three phases. (The round opening is connected to ground.) Essay answers are limited to about 500 words (3800 characters maximum, including spaces). 3800 Character(s) remaining Part C Find an expression for the rms value of the potential difference between any two of the phases. Assume that E is the familiar single-phase rms voltage. Some high-power home appliances, especially electric clothes dryers and hot-water heaters, are designed to operate between two of the phases rather than between one phase and neutral. Heavy-duty industrial motors are designed to operate from all three phases. But full three-phase power is rare in residential or office use. Express your answer in terms of epsilon rm. Part D Problem 35.63 Commercial electricity is generated and transmitted as three-phase electricity. Instead of a single emf epsilon = epsilon 0 cos wt, three separate wires carry currents for the emfs epsilon 1 = epsilon 0 cos omega t, 6 = epsilon 0 cos(wt + 120 degree), and epsilon 3 = epsilon 0 cos(wt - 120 degree). This is why the long- distance transmission lines you see in the countryside have three parallel wires, as do many distribution lines within a city Part A Draw a phasor diagram showing phasors for all three phases of a three-phase emf.

Explanation / Answer

PARTB)

transmission lines are 3 phase type

they are designated as R Y B

line will be balanced only when phasor sum of all three lines equal to zero

it has to satisfy that they should have same frequency

I=IR+IY+IB

=Ecos(wt)+Ecos(wt-120)+Ecos(wt+120)

=Ecos(wt)+Ecos(wt)*0.866-Esin(wt)*0.5-Ecos(wt)*0.866+Esin(wt)*0.5

=0

PARTC)

transmissionlines are starconnected

phase voltage=line voltage/sqrt(3)

vline=Ecos(wt)-Ecos(wt-120)

=sqrt(3)*phasevoltage

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