Lecture 3
Magnetic Materials and Transformers
Text Book: Chapter 4
Reference Book: Chapters 14, 15, 261, 262, and 263
1/25/09
ENG2MM3 Lecture 3
1
Magnetic Fields and Flux
Magnetic flux () has units of Webers (Wb)
Magnetic flux density (B = /A) in Wb/
Lecture 4
Nonideality of Transformers
Text Book Chapter: 5
Reference Book Chapters: 264, 265 and 266
2/3/09
ENG2MM3 Lecture 4
1
Exciting Current
The current in the primary windings that establishes
the flux is called the exciting current.
B (/A)
Io
2
Lecture 1
Fundamentals of Energy and Power System
Text Book 1: Page 236, 5882
Reference Book Chapters: 1 and 2; 51 to 54, 513 to 514; 61
to 65; 71 to 75, 79 to 712; 12, 18, and 20
ENG2MM3 Lecture 1
1
Reactions and Expectations
o Interesting ge
Question 1:
The results of the short and open circuit
test for a transformer rated at 1 kVA
200105 V is presented
Open Circuit
= 200 V
Short Circuit
= 11.3 V
= 0.32 A
=4A
= 40 W
= 31.4 W
ENG2MM3 Cantilever Equivalent Circuits and Voltage Regulation
1
a)
ENG 2MM3: Electrical Circuits & Power
Instructor: Dr. Matiar Howlader
Office: ITBA216
Extension: 26647
Email: [email protected]
Office hours: Instructor; Open Office Hours at ITBA216
Teaching Assistants and Office Hours:
Saba Mohtashami (sabamo
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Problem 11
First find the energy dissipated in the resistor:
R := 1
I := 20.0 A
2
t := 30 min
2
Pe := I R
Pe = ( 20.0 A ) 1
Pe = 0.4 kW
W e := Pe t
W e = 0.4 kW 30 min
60 sec
min
5
W e = 7.2 10 J
The kinetic energy in the car is given by 0.5Mv2
M := 20
Problem 21: Solution for homework
V = 169 sin 377t +
6
I = 282.8 sin 377t
6
From the given information:
Vpk := 169 V
Ipk := 282.8 A
Thus the RMS values are found by dividing the peak by the square root of two
Vrms :=
Vpk
2
Vrms = 119.501 V
Irms :=
Ipk
2
Lecture 2
Fundamentals of Energy and Power System
Text Book 1: Pages 7082
Reference Book: Chapters 21,225 and 226
1/16/2009
ENG2MM3 Lecture 2
1
Impedance in AC Circuits
Impedance is defined as the ratio between the
voltage across (V) and the current f
Question 1: [34]
Solution:
a)
[2]
[2]
[2]
[3]
[3]
b)
[3]
c)
[3]
[3]
[3]
d) [3]
e)
[3]
[2]
[2]
Question 2: [31]
Solution:
(a) The real power P = 680 W.
[1]
The apparent power
[3]
The reactive power
[3]
Because of capacitive load,
[1]
The power factor
leadi
Eng 2MM3 Assignment #2
Due: Nov 09, 2009 in Class
Question 1: (Points 87) A single phase stepup transformer is rated 60KVA, 300V
3000V. The results of Open Circuit and Short Circuit tests are as follows:
a) Calculate the rated current on each side of the
Eng 2MM3 Assignment #2
Due: March 12 by 4:15 PM at ITBA110 (ENG2MM3 Box).
Question 1: (Points 78) A single phase stepdown transformer is rated 80KVA, 4000V
400V. The results of Open Circuit and Short Circuit tests are as follows:
a) Calculate the rated
ENG2MM3 MidTerm Exam. #2, Term 1, 20082009 1 page 7:00pm ~ 8:40pm, Nov. 21, 2008
Points for Q1: 45
Q. 1. A threephase power system is shown in fig 1. The phase voltage of the Y connected generator is
220 V. The transmission line has an impedance of
per
ENG2MM3 MidTerm Exam. #1, Term 1, 2008
2 pages
1. The circuit shown is driven by a voltage of
7:0pm ~ 9:00pm, Oct. 16, 2008
at a frequency of
.
a) Find the input impedance
b) Find the power factor ( )for the circuit
c) Plot the phasor diagram for I using
Two Pages Formula Sheet for Final Examination of ENG2MM3
F em = BI
E = Bv
E = Bv [sin( )]
F em = BI sin = BI cos
E rms= 4.44 fN p
P
mech
2
n s=
120 f
RPM
P
n s=
2 f
rev / s
P
elec =
=
P out
100%
P in
P out
=
100%
P out + P loss
P in P loss
ENG2MM3 MidTerm Exam. #1, Term I, 2009
2 pages
7:00pm ~ 9:00pm, Oct. 20 2009
Question 1 [34 points]. Consider the circuit shown in Fig. 1. The voltage source is given
by
volt with the frequency of
. The resistance, inductance
and capacitance are
,
and
,
ENG 2MM3 Mid Term Examination II
November 18, 2009; 79 pm
Q1: A threephase power system is shown in the following figure. It consists of an ideal 240
volts Yconnected threephase generator connected through a threephase transmission line to
a connect
Q11. How fast (MPH) would a 2000 lb car have to move to have kinetic energy
that equals the energy dissipated in a 1 ! register carrying a 20.0amp current
for 30 min?
Ans: 89.12 mile/hr
Q12. A highvoltage capacitor bank operates at 7.97 kV and has a t
Solution for Q91.
Problem 92: Solution
Two motors connected to a 480 volt, threephase supply. The first motor is a 100 hp induction
motor with efficiency of 92%, and power factor of 0.8 lagging. The second motor is a 50 hp
synchronous motor operating a
ELECTRICAL CIRCUITS (cont.)
1. Thevenin Equivalent Circuit
Any linear electrical network with voltage and current sources and only
resistances can be replaced by an equivalent voltage source VTh in series
with an equ
MAGNETIC FIELDS AND CIRCUITS
1. Magnetic Fields
Magnetic fields are the fundamental mechanism by which motors and
generators convert electric energy to motion, and viceversa. Their
behaviour is described by Maxwell's
BEHAVIOUR OF MAGNETIC MATERIALS
1. Magnetic Domains
Iron and similar materials (cobalt, nickel, etc.) tend to have regions within
them where their atom's magnetic fields are closely aligned with each
other. These reg
ELECTRICAL ELEMENTS AND CIRCUITS
1. Linear Circuit Elements
Voltage source V (Volts, V)
Current source I (Amperes, A)
Resistor R (Ohms, )
=
Inductor L (Henrys, H)
=
Capacitor C (Fa
ENGINEER 2MM3
Fall 2015
Course Outline
ENGINEER 2MM3
Electrical Circuits and Power
Fall 2015
Course Outline
CALENDAR/COURSE DESCRIPTION
Fundamentals of electromechanical energy conversion. Motors and generators, transformers, single and
polyphase power ci
G1
G2
G3
G4
G5
G6
G7
G8
G9
G10
G11
G12
G13
G14
G15
G16
Sept
Oct
Nov
Dec
Mohammed Al Aryan
Eno Antai
Shahzaib Anwer
Surwinder Athwal
Vijay Balasundaram
Marty Burwell
Kaiyuan Cheng
Ben Cook
Nikhil D'mello
Reli De Sosa
Ken Duthie
Ayliah Fani
Hannah Freedberg