Electrical Engineering Solutions Manual | Key Formulas, MATLAB Code & Problem Answers

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Electrical Engineering Solutions Manual Overview

How are the line losses (PL and QL) calculated in the program? -
. . ANSWER ✓✓ PL is the real power loss calculated as PL =
real(SL), and QL is the reactive power loss calculated as QL =
imag(SL).


How are the real and reactive powers for source 1 calculated? - .
. ANSWER ✓✓ Real power P1 is obtained using P1 = real(S1) and
reactive power Q1 using Q1 = imag(S1).


How are the three identical transformers connected in Problem
3.8? - . . ANSWER ✓✓ Connected in Y on the high-voltage side
and Δ on the low-voltage side.


How can MATLAB be used to visualize voltage, power, and
current over time? - . . ANSWER ✓✓ By plotting v(t), p(t), and i(t)
over a specified time range using appropriate commands.


How can one improve note-taking based on the observations
from these notes? - . . ANSWER ✓✓ By ensuring clarity,
summarizing key points, and avoiding excessive placeholders.

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How can real and reactive power be estimated from the plots? - .
. ANSWER ✓✓ By analyzing the pr(t) and px(t) plots.


How can you identify the frequency of a waveform from a graph?
- . . ANSWER ✓✓ The frequency can be identified by measuring
the number of cycles per unit time.


How can you plot the instantaneous powers pa, pb, and pc in
MATLAB? - . . ANSWER ✓✓ Use the commands:
pa=25000*cos(wt).*cos(wt-36.87*pi/180); pb=25000*cos(wt-
120*pi/180).*cos(wt-120*pi/180-36.87*pi/180); pc=25000*cos(wt-
240*pi/180).*cos(wt-240*pi/180-36.87*pi/180); p = pa + pb + pc;
plot(wt, pa, wt, pb, wt, pc, wt, p), grid.


How do you calculate the line-to-line voltage at the high-voltage
terminals of the transformer in Problem 3.8? - . . ANSWER ✓✓
The line-to-line voltage is calculated as V1LL = √3 * V1, where V1
is the phase voltage.


How do you calculate the no-load generated voltage Eφ for the
alternator? - . . ANSWER ✓✓ Eφ = Vφ + (0.35 + j1.2)(Ia).


How do you calculate the phase voltage V1 in Problem 3.9? - . .
ANSWER ✓✓ V1 = 138.564̸ 0◦ + (1.2 + j6)(962.25̸ −36.87◦)(10−3).

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How do you calculate the phasor current for a delta-connected
load? - . . ANSWER ✓✓ Iab = Vab / Z, where Z is the impedance.


How do you calculate the phasor current for a Y-connected load?
- . . ANSWER ✓✓ Ia = Van / Z, where Z is the impedance.


How do you calculate the reactance X in the circuit? - . .
ANSWER ✓✓ X = |V|² / Q = (1200)² / 18000 = 80 Ω.


How do you calculate the resistance R in the circuit? - . .
ANSWER ✓✓ R = |V|² / P = (1200)² / 24000 = 60 Ω.


How do you calculate the total energy (W) in the MATLAB code
provided? - . . ANSWER ✓✓ W = P' * Dt, where P is the load and
Dt is the demand interval.


How do you calculate the total kvar of the system after adding
the capacitor bank? - . . ANSWER ✓✓ Total kvar is calculated by
subtracting the required kvar for the desired power factor from
the existing reactive power.


How do you calculate the total voltage across a delta-connected
load? - . . ANSWER ✓✓ Use the line-to-line voltage of the
source, which is 207.85 V rms.

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How do you convert from line-to-line voltage to phase voltage in
a Y-connected system? - . . ANSWER ✓✓ Phase voltage = Line-
to-line voltage / √3.


How do you find the instantaneous current i(t) from the complex
power S? - . . ANSWER ✓✓ Using S = 1/2 Vm Im*, where Vm is
the voltage and Im is the current.


How does the power factor affect transformer efficiency? - . .
ANSWER ✓✓ The power factor influences the real power
delivered and the reactive power, affecting overall efficiency.


How does the program handle the voltage magnitude of source
2? - . . ANSWER ✓✓ The voltage magnitude of source 2 is kept
constant and represented as a column array of the same length
as E1.


How is complex power (S) expressed in terms of real (P) and
reactive power (Q)? - . . ANSWER ✓✓ S = P + jQ, where j is the
imaginary unit.


How is the angle θ calculated for a lagging power factor of 0.8? -
. . ANSWER ✓✓ θ = cos⁻¹(0.8) = 36.87°.