Homework_4
docx
School
University Of Connecticut *
*We aren’t endorsed by this school
Course
3231
Subject
Mechanical Engineering
Date
Dec 6, 2023
Type
docx
Pages
3
Uploaded by ChefMeerkatPerson593
ECE 3231 Introduction to Modern Power Systems
Homework 4 Due 11/30/2023 by 11:59 pm
Q1)
A 90 MVA transformer is rated 345kV/115 kV and is connected in wye/wye configuration. The transformer impedance (purely inductive) is 7.5% on its own base. The transformer is tied to a 115 kV line whose impedance is 0.375+j1.5 ohms. Using 100MVA and rated voltage as the base values, find the total p.u. impedance of the transformer and line. (20 points)
Q2)
A single-phase 100-kVA, 1200/120-volt, 60-Hz distribution transformer has been showed in below. The load, which is connected to the 120-volt secondary winding, absorbs 60 kVA at 0.85 power factor lagging and is at 115 volts. Assuming an ideal transformer, calculate the following: (20 points)
(a) primary voltage
(b) load impedance
(c) load impedance referred to the primary
(d)the real and reactive power supplied to the primary winding
Q3)
A single
phase transformer rated 1.2kV/120V, 7.2kVA yields the following test results at 60Hz: ‐
(20 points)
Open
circuit test (primary
open)
‐
‐
Voltage V
2 = 125V; current I
2 = 1.5A; power consumption W
2 = 60W
Short
circuit test (secondary
shorted)
‐
‐
Voltage V
1 = 25V; current I
1 = 8.0A; power consumption W
1 = 54W
The diagram below already converts all variables to the primary side. Determine the Z
P and Z
m in per
Z = 0.375 + j 1.5 X = 7.5%
115 kV
345 kV
E
2
=
115
V
<
0
°
1200:120
unit value; (hint: Z
P can be neglected in calculating Z
m
; Z
m can be neglected in calculating Z
P
Q4)
A single-phase 50-kVA, 1200/120-volt, 60-Hz distribution transformer is used as a step-down transformer at the load end of a 1200-volt feeder whose series impedance is given below. (20 points)
The load at a 0.90 power factor lagging and at a rated secondary voltage. Neglecting the
transformer exciting current, determine:
(a) Determine the voltage I
2
, I
1
, E
1
(b) Determine the voltage V
s
(c) Calculate the P and Q power delivered to the sending end of the feeder
Q5)
A 2400/240 V, 60 Hz XFMR below. (20 points)
R
1
=
1
Ω
, X
l
1
=
2.5
Ω
R
2
=
0.012
Ω, X
l
2
=
0.015
Ω
X
M
=
2000
Ω
, R
he
=
negligible
1200:120
120<0°
Determine input voltage if output voltage is 240 V (rms) and feeding a load 1.5 ohm and PF = 0.9 (lagging).
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help
Related Documents
Related Questions
The following data were obtained on a 50 kVA 2400/120 V transformer:
Open circuit test, instruments on low voltage side:
Waltmeter reading = 396 Watts
Ammeter reading = 9.65 amperes
Voltmeter reading = 120 Volts
Short circuit test, instruments on high voltage side:
Waltmeter reading = 810 Watts
Ammeter reading = 20.8 amperes
Voltmeter reading = 92 Volts
Find the efficiency when rated kVA is delivered to a load having a power
factor of 0.8 lagging.The following data were obtained on a 50 kVA 2400/120 V transformer :
Open circuit test, instruments on low voltage side:
Waltmeter reading = 396 Watts
Ammeter reading = 9.65 amperes
Voltmeter reading = 120 Volts
Short circuit test, instruments on high voltage side:
Waltmeter reading = 810 Watts
Ammeter reading = 20.8 amperes
Voltmeter reading = 92 Volts
Find the efficiency when rated kVA is delivered to a load having a power
factor of 0.8 lagging.
arrow_forward
Don't Use Chat GPT Will Upvote And Give Solution In 30 Minutes Please
arrow_forward
The arc length voltage characteristic of a DC arc is given by the equation V=24+4L where
'V' is the arc voltage in volts and L' is the length in mm. The static volt-ampere
characteristic of the power source is approximated by a straight line with no load voltage of
80V and the short circuit current of 600A. Then the optimum arc length is
(mm).
arrow_forward
4. A circuit contains a 20-2 resistor and
an inductor with an inductance of
0.093 H. If the circuit has a frequency
of 60 Hz, what is the total impedance
of the circuit?
5. An R-L series circuit has a power
factor of 86%. By how many degrees
are the voltage and current out of
phase with each other?
6. An R-L series circuit has an apparent
power of 230 VA and a true power of
180 W. What is the reactive power?
7. The resistor in an R-L series circuit
has a voltage drop of 53 V, and the
inductor has a voltage drop of 28 V.
What is the applied voltage of the
circuit?
arrow_forward
A balanced positive-sequence wye-connected
60-Hz three-phase source has line-to-line
voltages of VL = 440 V rms. This source is
connected to a balanced wye-connected load.
Each phase of the load consists of a 0.5-H
inductance in series with a 50-? resistance.
Assume that the phase of Van is zero.
A) Find the line-to-neutral voltage phasor
Van.
Enter your answer using polar notation.
Express argument in degrees.
B) Find the line-to-neutral voltage phasor
Vbn.
Enter your answer using polar notation.
Express argument in degrees.
C) Find the line-to-neutral voltage phasor
Vcn.
Enter your answer using polar notation.
Express argument in degrees.
D) Find the line-to-line voltage phasor Vab.
Enter your answer using polar notation.
Express argument in degrees.
arrow_forward
Good solution
arrow_forward
7. A step-down transformer has a turn ratio Np/Ns of 4:1. If the primary voltage Vp is
120 V(rms), the secondary voltage Vs is
(а) 480 V
(b) 120 V
(c)30 V
(d) It cannot be determined.
arrow_forward
Please Solution Step by Step
arrow_forward
Example 5: A 2400 V/400V single-phase transformer takes a no-load current of 0.5A and the
core loss is 400 W. Determine the values of the angle p. and the magnetising and core loss
components of the no-load current.
arrow_forward
2. For the circuit shown in fig. 2. Find the Node Voltages using Nodal
Analysis.
W
voor
20
200
10
I -
6A 20°
20
100
宣
Fig.2
E-30V 20°
arrow_forward
Find out the error for the given program
io = 1.7e-8; % dark saturation current in amperes
tc = 27;
% cell temperature in degree celsius
isc = 250 ; % short circuit current density A/ square meter
pin = 820; % solar radiation in w/square meter
k =1.381e-23; % Boltzmann's gas constant
e= 1.602e-19; % electronic charge
t= 273+tc
% cell temperature in Kelvin
vmax=0.526; % mayi mum voltage in volts
imax = (e*vmax)*(isc+io)/(k*t+e*vmax)
pmax= vmax*imax
efficiency = (pin/pmax)*100
O error in efficiency
O no error
O Error in pmax
O Error in imax
O no output
arrow_forward
If the impedance Z1 = 10 +j10 and the impedance Z2 = 10 - j0 are connected in series, the equivalent impedance
would be:
O A. 20-j10 ohms
O B. 20+ j20 ohms
O C. None of the other choices are correct
O D. 20 ohms
O E. 20+ j 10 ohms
arrow_forward
Don't use chatgpt will upvote
arrow_forward
In the network below, find the power
associated to the current source, for V1 = 10
V.
Vi +
2 A (T
14 V
Select one:
а. -14
b. -4
С. -8
d. -20
е. -18
2.
arrow_forward
SEE MORE QUESTIONS
Recommended textbooks for you

Electrical Transformers and Rotating Machines
Mechanical Engineering
ISBN:9781305494817
Author:Stephen L. Herman
Publisher:Cengage Learning
Related Questions
- The following data were obtained on a 50 kVA 2400/120 V transformer: Open circuit test, instruments on low voltage side: Waltmeter reading = 396 Watts Ammeter reading = 9.65 amperes Voltmeter reading = 120 Volts Short circuit test, instruments on high voltage side: Waltmeter reading = 810 Watts Ammeter reading = 20.8 amperes Voltmeter reading = 92 Volts Find the efficiency when rated kVA is delivered to a load having a power factor of 0.8 lagging.The following data were obtained on a 50 kVA 2400/120 V transformer : Open circuit test, instruments on low voltage side: Waltmeter reading = 396 Watts Ammeter reading = 9.65 amperes Voltmeter reading = 120 Volts Short circuit test, instruments on high voltage side: Waltmeter reading = 810 Watts Ammeter reading = 20.8 amperes Voltmeter reading = 92 Volts Find the efficiency when rated kVA is delivered to a load having a power factor of 0.8 lagging.arrow_forwardDon't Use Chat GPT Will Upvote And Give Solution In 30 Minutes Pleasearrow_forwardThe arc length voltage characteristic of a DC arc is given by the equation V=24+4L where 'V' is the arc voltage in volts and L' is the length in mm. The static volt-ampere characteristic of the power source is approximated by a straight line with no load voltage of 80V and the short circuit current of 600A. Then the optimum arc length is (mm).arrow_forward
- 4. A circuit contains a 20-2 resistor and an inductor with an inductance of 0.093 H. If the circuit has a frequency of 60 Hz, what is the total impedance of the circuit? 5. An R-L series circuit has a power factor of 86%. By how many degrees are the voltage and current out of phase with each other? 6. An R-L series circuit has an apparent power of 230 VA and a true power of 180 W. What is the reactive power? 7. The resistor in an R-L series circuit has a voltage drop of 53 V, and the inductor has a voltage drop of 28 V. What is the applied voltage of the circuit?arrow_forwardA balanced positive-sequence wye-connected 60-Hz three-phase source has line-to-line voltages of VL = 440 V rms. This source is connected to a balanced wye-connected load. Each phase of the load consists of a 0.5-H inductance in series with a 50-? resistance. Assume that the phase of Van is zero. A) Find the line-to-neutral voltage phasor Van. Enter your answer using polar notation. Express argument in degrees. B) Find the line-to-neutral voltage phasor Vbn. Enter your answer using polar notation. Express argument in degrees. C) Find the line-to-neutral voltage phasor Vcn. Enter your answer using polar notation. Express argument in degrees. D) Find the line-to-line voltage phasor Vab. Enter your answer using polar notation. Express argument in degrees.arrow_forwardGood solutionarrow_forward
- 7. A step-down transformer has a turn ratio Np/Ns of 4:1. If the primary voltage Vp is 120 V(rms), the secondary voltage Vs is (а) 480 V (b) 120 V (c)30 V (d) It cannot be determined.arrow_forwardPlease Solution Step by Steparrow_forwardExample 5: A 2400 V/400V single-phase transformer takes a no-load current of 0.5A and the core loss is 400 W. Determine the values of the angle p. and the magnetising and core loss components of the no-load current.arrow_forward
- 2. For the circuit shown in fig. 2. Find the Node Voltages using Nodal Analysis. W voor 20 200 10 I - 6A 20° 20 100 宣 Fig.2 E-30V 20°arrow_forwardFind out the error for the given program io = 1.7e-8; % dark saturation current in amperes tc = 27; % cell temperature in degree celsius isc = 250 ; % short circuit current density A/ square meter pin = 820; % solar radiation in w/square meter k =1.381e-23; % Boltzmann's gas constant e= 1.602e-19; % electronic charge t= 273+tc % cell temperature in Kelvin vmax=0.526; % mayi mum voltage in volts imax = (e*vmax)*(isc+io)/(k*t+e*vmax) pmax= vmax*imax efficiency = (pin/pmax)*100 O error in efficiency O no error O Error in pmax O Error in imax O no outputarrow_forwardIf the impedance Z1 = 10 +j10 and the impedance Z2 = 10 - j0 are connected in series, the equivalent impedance would be: O A. 20-j10 ohms O B. 20+ j20 ohms O C. None of the other choices are correct O D. 20 ohms O E. 20+ j 10 ohmsarrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
- Electrical Transformers and Rotating MachinesMechanical EngineeringISBN:9781305494817Author:Stephen L. HermanPublisher:Cengage Learning

Electrical Transformers and Rotating Machines
Mechanical Engineering
ISBN:9781305494817
Author:Stephen L. Herman
Publisher:Cengage Learning