In: Electrical Engineering

A 1.5 KVA, 220/120 V, 60Hz real step-down transformer has the following parameters that are all referred to the primary-side: the total copper loss R = 2.4 Ω, the core loss Rc = 2.4 KΩ, the magnetization reactance Xm = 2 KΩ, and all the leakages are negligible. Suppose that the output port in the secondary-side is operated at full-load and rated voltage with the unity power factor p.f. = 1.

(a) Find the power factor p.f.1 at the primary-side input port;

(b) What is the voltage regulation (V R)?

(c) Determine the power efficiency η .

4.11)The equivalent circuit parameters of a 150 kVA, 2400 V/ 240
V, 60 Hz transformer are as follows:
RHV = 0.21Ω, RLV = 2mΩ, XlHV = 0.45Ω, XlLV = 4.6mΩ, XmHV =
1.6kΩ, and RcHV = 12kΩ.
The transformer delivers to a load, rated current at a power
factor of 0.85 lagging at rated voltage. Determine the input
voltage, current, apparent power and power factor, (a) using the
approximate equivalent circuit, and (b) not using the approximate
equivalent circuit.
Problem...

In a step-down converter, Vd = 25V, Vo = 15 V, Io = 1.5 A, Ls
= 200 µH, C = 500µF, and fs=50 kHz.
(a) Plot the iL and υL for a period of Ts showing clearly the
values of iLpeak, and υL. Assume boundary operation.

What is difference between a 120V/240V step-up and 240/120 V
step-down single phase transformers? Both transformers are rated 5
kVA and operated at 60 Hz. Explain your answer by means of relevant
diagrams and equations.What is difference between a 120V/240V
step-up and 240/120 V step-down single phase transformers? Both
transformers are rated 5 kVA and operated at 60 Hz. Explain your
answer by means of relevant diagrams and equations.What is
difference between a 120V/240V step-up and 240/120 V step-down
single...

A single phase, 300???, 11??/2.2??, 60 ?? transformer has the
following parameters referred to the high-voltage side: ?? =
57.6??, ?? = 16.34??, ??? = 2.784? and ??? = 3.5?. If a load of
????? = 16∠30°? connected to the low-voltage side: a)
Find the voltage regulation? b) Draw the phasor diagram? c) Find
the efficiency of the transformer? d) Repeat part a and b at ?????
= 16∠ − 30°??

(A) A plug-in transformer supplies 9.00 V to a video game system. How many turns are in its secondary coil if its input voltage is 120 V and the primary coil has 381 turns? What is its input current when its output is 1.33 A?
(B)What is the characteristic time constant of a 24.2 mH inductor that has a resistance of 4.08 Ω? If it is connected to a 12.0 V battery, what is the current after 12.5 ms?
(C)Two...

Let V be the set of all ordered pairs of real numbers. Consider
the following addition and scalar multiplication operations V. Let
u = (u1, u2) and v = (v1, v2).
Show that V is not a vector space.
• u ⊕ v = (u1 + v1 + 1, u2 + v2 + 1 )
• ku = (ku1 + k − 1, ku2 + k − 1)
1)Show that the zero vector is 0 = (−1, −1).
2)Find the...

A star-connected induction motor has the following rated
parameters: Voltage UN = 400 V, current IN = 8 A, frequency fN = 50
Hz, speed nN = 1480 rpm, power factor cos ĳN = 0.8, efficiency ȘN =
0.9, magnetizing inductance Lm = 280 mH, stator leakage inductance
LVı = 9 mH and rotor leakage inductance LUı = 14 mH.
For the rated operating point of the motor, calculate the
per-unit values for electric active power Pel, mechanical power
Pmech,...

Q3)
A three-phase, Y-connected, 220 V, 13 kW, 60 Hz, six-pole induction
motor has the following
parameter values in Ω/phase referred to the stator:
R1 = 0.3 Ω. R2' = 0.15 Ω
X1 = 0.5 Ω. X2'= 0.21 Ω Xm = 13.25 Ω
The total rotational losses are 450 W. The core loss is lumped in
with the rotational losses. For a slip of 0.02,
and based on approximate equivalent circuit, determine:
(i) The rotor speed.
(ii) The stator current....

A 440-V, 3-φ 50-Hz, 4 poles, 37.3 kW, Y-connected induction
motor has the following parameters:
R1= 0.1 Ω, X1 = 0.4 Ω , R2′ = 0.15 Ω , X2′ = 0.44 Ω
Motor has stator core loss of 1250 W and rotational loss of
1000 W. It draws a no-load line current of 20 A at a p.f. of 0.09
(lag). When motor operates at a slip of 3%, calculate
a. input line current and p.f. [57.4@29°A, 0.875 lag]
b....

A three-phase, 11.2-kW, 1750-rpm, 460-V, 60-Hz, four-pole,
Y-connected induction motor has the following parameters: Rs = 0.53
Ω, R’r = 0.38 Ω, Xs = 1.23 Ω, X’r = 1.45 Ω, and Xm = 25.2 Ω. The
motor is controlled by varying both the voltage and frequency. The
volts/hertz ratio, which corresponds to the rated voltage and rated
frequency, is maintained constant.
a) Calculate the maximum torque, Tm and the corresponding speed,
ꞷm for 60 Hz and 30 Hz.
b) Repeat...

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