This document provides a history of electricity and discusses AC and DC theory. It begins with a brief history of electricity starting in 1800 with Volta's battery and continuing through key developments in AC motors, generators, and power distribution. It then explains some key differences between AC and DC, including that AC allows for more efficient power transmission using transformers. The document goes on to discuss AC theory in depth, including sine waves, RMS values, reactance, power factors, and phasors. It notes the rise of non-linear loads has led to harmonics issues. New energy definitions are being developed to address non-sinusoidal waveforms found with modern loads.
Electrical Technology Notes for preparation.
Kindly note :- Don't forget to use class note book while studying.
Use my theory questions to clear ET and solved all the problems.
Alternating current (AC), is an electric current in which the flow of electric charge periodically reverses direction, whereas in direct current (DC, also dc), the flow of electric charge is only in one direction.
this contant is physics related.Here AC current explain on the purpose of presentation with some equation and circuit diagram.i thaink it wiil be very effective for the students.
Starting with a little bit of history, this presentation dives into anything and everything AC, including resistive, inductive, and capacitive load, energy, instantaneous power, complex circuits, phasors, and more.
Take a look at the history of AC and DC power distributions, the differences between the two, and usage today - presented at NC Meter School 2022 Advance Track.
Electrical Technology Notes for preparation.
Kindly note :- Don't forget to use class note book while studying.
Use my theory questions to clear ET and solved all the problems.
Alternating current (AC), is an electric current in which the flow of electric charge periodically reverses direction, whereas in direct current (DC, also dc), the flow of electric charge is only in one direction.
this contant is physics related.Here AC current explain on the purpose of presentation with some equation and circuit diagram.i thaink it wiil be very effective for the students.
Starting with a little bit of history, this presentation dives into anything and everything AC, including resistive, inductive, and capacitive load, energy, instantaneous power, complex circuits, phasors, and more.
Take a look at the history of AC and DC power distributions, the differences between the two, and usage today - presented at NC Meter School 2022 Advance Track.
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Learn about the cost savings, reduced environmental impact, and minimal disruption associated with trenchless technology. Discover detailed explanations of popular techniques such as pipe bursting, cured-in-place pipe (CIPP) lining, and directional drilling. Understand how these methods can be applied to various types of infrastructure, from residential plumbing to large-scale municipal systems.
Ideal for homeowners, contractors, engineers, and anyone interested in modern plumbing solutions, this guide provides valuable insights into why trenchless pipe repair is becoming the preferred choice for pipe rehabilitation. Stay informed about the latest advancements and best practices in the field.
Final project report on grocery store management system..pdfKamal Acharya
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In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
Water scarcity is the lack of fresh water resources to meet the standard water demand. There are two type of water scarcity. One is physical. The other is economic water scarcity.
1. Theory of AC and
DC Meter Testing
Prepared by Bill Hardy, TESCO
For North Carolina Electric Meter School
Single Phase
Tuesday, June 25, 2019 at 3:15 p.m.
2. 2
A Little History
• 1800 Volta
– First electric battery
• 1830-31 Faraday and Henry
– Changing magnetic field can induce an electric
current. Build first very crude electric motors in lab.
• 1832 Pixii
– First crude generation of an AC current.
• 1856 Siemens
– First really practical electric motor
• 1860s Varley, Siemens and Wheatstone
– Each develop electric dynamos (DC Generators).
3. 3
A Little History
• 1870s
– First electric railroad and street lights in Berlin (DC).
• 1880
– First electric elevator (DC).
• 1885-88 Thomson, Ferraris, Tesla
– Each develop AC electric induction motors.
– Tesla is granted a US patent for induction motor in
1888.
• 1890 Dolivo-Dobrovolsky
– First three phase generator, motor and transformer
4. 4
A Little History
• Edison and Westinghouse
– Edison favored DC power distribution, Westinghouse
championed AC distribution.
– The first US commercial electric systems were
Edison’s DC systems.
• First AC system was in 1893 in Redlands, CA.
Developed by Almirian Decker it used 10,000
volt, three phase primary distribution.
• Siemens, Gauland and Steinmetz were other
pioneers.
5. 5
War of the Currents
Thomas Edison George Westinghouse Nikola Tesla
6. 6
AC Theory - History
• By 1900 AC power systems had won the
battle for power distribution.
– Transformers allowed more efficient
distribution of power over large areas.
– AC motors were cheaper and easier to build.
– AC electric generators were easier to build.
7. 7
AC vs DC
• Direct Current (DC) – an electric current
that flows in one direction.(IEEE100)
• Alternating Current (AC) – an electric
current that reverses direction at regularly
recurring intervals of time. (IEEE100)
8. 8
AC Circuits
• An AC circuit has three general characteristics
– Value
– Frequency
– Phase
• In the US, the household value is 120 Volts with
other common voltages being 208, 240, 277 and
480 Volts. The frequency is 60 Hertz (cycles per
second).
9. 9
AC Theory – Sine Wave
)2sin( ftVV pk
0
)2sin(2 ftVV rms
120rmsV
169pkV
10. AC Theory - Phase
Sine Wave
(15.000)
(10.000)
(5.000)
0.000
5.000
10.000
15.000
0 60 120 180 240 300 360 420 480 540 600 660 720
Degrees
Amplitude
)2sin(10 ftV )302sin(10 ftI
Here current LAGS voltage.
11. 11
AC vs DC
• In DC theory we learned
– Ohm’s Law
• Voltage = Current x Resistance
• V = IR
– Power
• P = I2R = V2/R
• For AC we would like the same equations to apply.
– Specifically we want to be able to say that a DC
voltage of 10 Volts applied to a resistor of value R
produces the same power dissipation as an AC
voltage of 10 volts applied to the same resistor.
12. 12
AC Theory – RMS
• For DC voltage to equal AC voltage we need
dtftV
RR
Vdc
)2(sin
1 22
0
2
R
V
R
Vdc
2
2
0
2
DCVV 20
13. AC Theory - RMS
)sin(68.169)sin(2120 ttV
(200)
(150)
(100)
(50)
0
50
100
150
200
0 60 120 180 240 300 360 420 480 540 600 660 720
Amplitude
Degrees
Sine Wave
RMS Value
14. 14
AC Theory – RMS
• So if we want to have the V in our equation for
an AC signal represent the same value as the its
DC counterpart we have
• By convention in AC theory we refer to VDC as
the RMS (Root Mean Squared) voltage.
• When we talk about AC values we always mean
the RMS value not the peak value unless we say
so specifically
)2sin(2)( ftVtV DC
16. AC Theory – Resistive Load
Sine Wave
-200
-150
-100
-50
0
50
100
150
200
0 60 120 180 240 300 360 420 480 540 600 660 720
Degrees
Amplitude
AC
RVrms
Irms
Resistors are measured in Ohms. When an AC voltage is applied to a resistor, the
current is in degrees. A resistive load is considered a “linear” load because when
the voltage is sinusoidal the current is sinusoidal.
17. 17
AC Theory – Inductive Load
Sine Wave
-200
-150
-100
-50
0
50
100
150
200
0 60 120 180 240 300 360 420 480 540 600 660 720
Degrees
Amplitude
AC
LVrms
Irms
Inductors are measured in Henrys. When an AC voltage is applied to an inductor,
the current is 90 degrees out of phase. We say the current “lags” the voltage. A
inductive load is considered a “linear” load because when the voltage is sinusoidal
the current is sinusoidal.
18. 18
AC Theory – Capacitive Load
Sine Wave
-200
-150
-100
-50
0
50
100
150
200
0 60 120 180 240 300 360 420 480 540 600 660 720
Degrees
Amplitude
AC CVrms
Irms
Capacitors are measured in Farads. When an AC voltage is applied to a capacitor,
the current is 90 degrees out of phase. We say the current “leads” the voltage. A
capacitive load is considered a “linear” load because when the voltage is
sinusoidal the current is sinusoidal.
19. 19
AC Theory – Active Power
• Active Power is defined as P = VI
• Power is a rate, i.e. Energy per unit time.
• The Watt is the unit for Power
– 1 Watt = 1000 Joules/sec
• Since the voltage and current at every point in
time for an AC signal is different, we have to
distinguish between instantaneous power and
average power.
• Generally when we say “power” we mean
average power.
20. 20
AC Theory – Energy
• Energy is power integrated over a period of time.
• The units of Energy are:
– Watt-Hour (abbreviated Wh)
– Kilowatt-Hour (abbreviated kWh)
• A Wh is the total energy consumed when a load
draws one Watt for one hour.
21. 21
AC Theory – Instantaneous Power
Sine Wave
(200)
(150)
(100)
(50)
0
50
100
150
200
0 60 120 180 240 300 360 420 480 540 600 660 720
Degrees
Amplitude
(25000)
(20000)
(15000)
(10000)
(5000)
0
5000
10000
15000
20000
25000
WATTS
)2sin(2120 ftV )2sin(296 ftI )2(sin23040 2
ftP
For a resistive load: ))2cos(1()(sin2 2
tVItVIvip
P = 11520 Watts
22. 22
AC Theory – Instantaneous Power
Sine Wave
-200
-150
-100
-50
0
50
100
150
200
0 60 120 180 240 300 360 420 480 540 600 660 720
Degrees
Amplitude
-15000
-10000
-5000
0
5000
10000
15000
)2sin(2120 ftV )902sin(296 ftI )2sin(11520 ftP
For an inductive load:
P = 0 Watts
)2sin()90sin()sin(2 tVIttVIvip
23. 23
AC Theory – Instantaneous Power
Sine Wave
-200
-150
-100
-50
0
50
100
150
200
0 60 120 180 240 300 360 420 480 540 600 660 720
Degrees
Amplitude
-15000
-10000
-5000
0
5000
10000
15000
)2sin(2120 ftV )902sin(296 ftI )2sin(11520 ftP
For an capacitive load:
P = 0 Watts
)2()90()(2 tVISintSintVISinvip
24. 24
AC Theory – Complex Circuits
• Impedance – The equivalent to the concept of resistance
for an AC circuit. It is also measured in Ohms.
Designated by the symbol X.
• In AC circuits non-resistive impedance affects both the
amplitude and phase of the current.
• A resistor R has an impedance which is frequency
independent. There is no phase shift.
• An inductor has an impedance which is proportional the
frequency, XL = 2πfL. The phase is shifted by 90
degrees lagging.
• A capacitor has an impedance which is inversely
proportional the frequency, XC = 1/2πfC. The phase is
shifted by 90 degrees leading.
25. 25
AC Theory – Complex Circuits
AC
C
Vrms
Irms
R
L
22
)
1
(
C
LR
V
I
Amplitude (Current)
R
C
L )
1
(
arctan
Phase (Current)
VC
V
VL
VC
VR
27. Time Out for Trig
(Right Triangles)
c
a
)cos(
a
b
)tan(
a
c
b
90°
The Right Triangle:
The Pythagorean theory
c2 = a2 + b2
c
b
)sin(
28. 28
AC Theory – Power Triangle
(Sinusoidal Waveforms)
If V = sin(ωt) and I = sin(ωt - θ) (and the load is linear)
then
Active Power = VIcos(θ) Watts
Reactive Power = VIsin(θ) VARs
Apparent Power = VI VA
Power Factor = Active/Apparent = cos(θ)
Watts
VARs
29. 29
Harmonics
Curse of the Modern World
• Every thing discussed so far was based on
“Linear” loads.
– For linear loads the current is always a simple
sine wave. Everything we have discussed is
true.
• For nearly a century after AC power was in
use ALL loads were linear.
• Today, many loads are NON-LINEAR.
31. 31
AC Theory - Phasors
• An easier way to view AC data
CURRENTVOLTAGE
A
B
C
Va 0°
I a 0°
Vb 120°
I b 120°
Vc 240°
I c 240°
THE VECTOR
DIAGRAM
32. AC Theory - Phasors
• The length of the phasor is
proportional to the value of the
quantity
• The angle of the phasor (by
convention phase A is drawn
as horizontal) shows the phase
of the quantity relative to
phase A voltage.
• Here the current “lags” the
voltage by 30 degrees.
)302sin(25.2 ftI
)02sin(2120 ftV
CURRENTVOLTAGE
A
Va 0°
I a 30°
THE VECTOR
DIAGRAM
33. 33
AC Theory - Phasors
Phasors are particularly useful in poly-phase situations
CURRENTVOLTAGE
A
B
C
Va 0°
I a 12°
Vb 120°
I b 126°
Vc 240°
I c 247°
THE VECTOR
DIAGRAM
34. 34
New Energy Definitions
• At the moment there is no non-sinusoidal
definition for VA
• New ANSI Standard coming very soon
C12.31
39. 39
Questions and Discussion
Bill Hardy, CTO
TESCO – The Eastern Specialty Company
Bristol, PA
865-279-1090 (cell)
215-785-2338 (office)
This presentation can also be found on the TESCO
website: www.tescometering.com