An electric circuit is a path in which electrons from a voltage or current source flow. The point where those electrons enter an electrical circuit is called the "source" of electrons.
An electric circuit is a path in which electrons from a voltage or current source flow. The point where those electrons enter an electrical circuit is called the "source" of electrons.
Industrial Star Delta Starter for a 3-Phase Induction Motorelprocus
The most basic feature of an Induction motor is its self starting mechanism. Due to the rotating magnetic field, an emf is induced in the rotor, because of which current starts flowing in the rotor.
Ohm's Law V = I x R (Volts = Current x Resistance). The Ohm (Ω) is a unit of electrical resistance equal to that of a conductor in which a current of one ampere is produced by a potential of one volt across its terminals. 1)Measurement of Low resistance: 1) Ammeter Voltmeter method: This is very popular method for measurement of medium resistances since ...
this slides are used for the definition of capacitor and inductor and also it types
this slides describe circuit of capacitor and inductors like capacitor in series and parallel and vice versa
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.
Industrial Star Delta Starter for a 3-Phase Induction Motorelprocus
The most basic feature of an Induction motor is its self starting mechanism. Due to the rotating magnetic field, an emf is induced in the rotor, because of which current starts flowing in the rotor.
Ohm's Law V = I x R (Volts = Current x Resistance). The Ohm (Ω) is a unit of electrical resistance equal to that of a conductor in which a current of one ampere is produced by a potential of one volt across its terminals. 1)Measurement of Low resistance: 1) Ammeter Voltmeter method: This is very popular method for measurement of medium resistances since ...
this slides are used for the definition of capacitor and inductor and also it types
this slides describe circuit of capacitor and inductors like capacitor in series and parallel and vice versa
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.
Starting with a little bit of history, this presentation dives into the theory of AC and DC Meter Testing, including resistive, inductive, and capacitive load, energy, instantaneous power, complex circuits, phasors, and more. Presented at NC Meter School 2022.
Starting with a little bit of history, this presentation dives into the theory of AC and DC Meter Testing, including resistive, inductive, and capacitive load, energy, instantaneous power, complex circuits, phasors, and more. 6/25/2019
Starting with a little bit of history, this presentation dives into the theory of AC and DC Meter Testing, including resistive, inductive, and capacitive load, energy, instantaneous power, complex circuits, phasors, and more. 6/26/2019
Epistemic Interaction - tuning interfaces to provide information for AI supportAlan Dix
Paper presented at SYNERGY workshop at AVI 2024, Genoa, Italy. 3rd June 2024
https://alandix.com/academic/papers/synergy2024-epistemic/
As machine learning integrates deeper into human-computer interactions, the concept of epistemic interaction emerges, aiming to refine these interactions to enhance system adaptability. This approach encourages minor, intentional adjustments in user behaviour to enrich the data available for system learning. This paper introduces epistemic interaction within the context of human-system communication, illustrating how deliberate interaction design can improve system understanding and adaptation. Through concrete examples, we demonstrate the potential of epistemic interaction to significantly advance human-computer interaction by leveraging intuitive human communication strategies to inform system design and functionality, offering a novel pathway for enriching user-system engagements.
JMeter webinar - integration with InfluxDB and GrafanaRTTS
Watch this recorded webinar about real-time monitoring of application performance. See how to integrate Apache JMeter, the open-source leader in performance testing, with InfluxDB, the open-source time-series database, and Grafana, the open-source analytics and visualization application.
In this webinar, we will review the benefits of leveraging InfluxDB and Grafana when executing load tests and demonstrate how these tools are used to visualize performance metrics.
Length: 30 minutes
Session Overview
-------------------------------------------
During this webinar, we will cover the following topics while demonstrating the integrations of JMeter, InfluxDB and Grafana:
- What out-of-the-box solutions are available for real-time monitoring JMeter tests?
- What are the benefits of integrating InfluxDB and Grafana into the load testing stack?
- Which features are provided by Grafana?
- Demonstration of InfluxDB and Grafana using a practice web application
To view the webinar recording, go to:
https://www.rttsweb.com/jmeter-integration-webinar
DevOps and Testing slides at DASA ConnectKari Kakkonen
My and Rik Marselis slides at 30.5.2024 DASA Connect conference. We discuss about what is testing, then what is agile testing and finally what is Testing in DevOps. Finally we had lovely workshop with the participants trying to find out different ways to think about quality and testing in different parts of the DevOps infinity loop.
LF Energy Webinar: Electrical Grid Modelling and Simulation Through PowSyBl -...DanBrown980551
Do you want to learn how to model and simulate an electrical network from scratch in under an hour?
Then welcome to this PowSyBl workshop, hosted by Rte, the French Transmission System Operator (TSO)!
During the webinar, you will discover the PowSyBl ecosystem as well as handle and study an electrical network through an interactive Python notebook.
PowSyBl is an open source project hosted by LF Energy, which offers a comprehensive set of features for electrical grid modelling and simulation. Among other advanced features, PowSyBl provides:
- A fully editable and extendable library for grid component modelling;
- Visualization tools to display your network;
- Grid simulation tools, such as power flows, security analyses (with or without remedial actions) and sensitivity analyses;
The framework is mostly written in Java, with a Python binding so that Python developers can access PowSyBl functionalities as well.
What you will learn during the webinar:
- For beginners: discover PowSyBl's functionalities through a quick general presentation and the notebook, without needing any expert coding skills;
- For advanced developers: master the skills to efficiently apply PowSyBl functionalities to your real-world scenarios.
"Impact of front-end architecture on development cost", Viktor TurskyiFwdays
I have heard many times that architecture is not important for the front-end. Also, many times I have seen how developers implement features on the front-end just following the standard rules for a framework and think that this is enough to successfully launch the project, and then the project fails. How to prevent this and what approach to choose? I have launched dozens of complex projects and during the talk we will analyze which approaches have worked for me and which have not.
GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using Deplo...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
Essentials of Automations: Optimizing FME Workflows with ParametersSafe Software
Are you looking to streamline your workflows and boost your projects’ efficiency? Do you find yourself searching for ways to add flexibility and control over your FME workflows? If so, you’re in the right place.
Join us for an insightful dive into the world of FME parameters, a critical element in optimizing workflow efficiency. This webinar marks the beginning of our three-part “Essentials of Automation” series. This first webinar is designed to equip you with the knowledge and skills to utilize parameters effectively: enhancing the flexibility, maintainability, and user control of your FME projects.
Here’s what you’ll gain:
- Essentials of FME Parameters: Understand the pivotal role of parameters, including Reader/Writer, Transformer, User, and FME Flow categories. Discover how they are the key to unlocking automation and optimization within your workflows.
- Practical Applications in FME Form: Delve into key user parameter types including choice, connections, and file URLs. Allow users to control how a workflow runs, making your workflows more reusable. Learn to import values and deliver the best user experience for your workflows while enhancing accuracy.
- Optimization Strategies in FME Flow: Explore the creation and strategic deployment of parameters in FME Flow, including the use of deployment and geometry parameters, to maximize workflow efficiency.
- Pro Tips for Success: Gain insights on parameterizing connections and leveraging new features like Conditional Visibility for clarity and simplicity.
We’ll wrap up with a glimpse into future webinars, followed by a Q&A session to address your specific questions surrounding this topic.
Don’t miss this opportunity to elevate your FME expertise and drive your projects to new heights of efficiency.
UiPath Test Automation using UiPath Test Suite series, part 4DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 4. In this session, we will cover Test Manager overview along with SAP heatmap.
The UiPath Test Manager overview with SAP heatmap webinar offers a concise yet comprehensive exploration of the role of a Test Manager within SAP environments, coupled with the utilization of heatmaps for effective testing strategies.
Participants will gain insights into the responsibilities, challenges, and best practices associated with test management in SAP projects. Additionally, the webinar delves into the significance of heatmaps as a visual aid for identifying testing priorities, areas of risk, and resource allocation within SAP landscapes. Through this session, attendees can expect to enhance their understanding of test management principles while learning practical approaches to optimize testing processes in SAP environments using heatmap visualization techniques
What will you get from this session?
1. Insights into SAP testing best practices
2. Heatmap utilization for testing
3. Optimization of testing processes
4. Demo
Topics covered:
Execution from the test manager
Orchestrator execution result
Defect reporting
SAP heatmap example with demo
Speaker:
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
Dev Dives: Train smarter, not harder – active learning and UiPath LLMs for do...UiPathCommunity
💥 Speed, accuracy, and scaling – discover the superpowers of GenAI in action with UiPath Document Understanding and Communications Mining™:
See how to accelerate model training and optimize model performance with active learning
Learn about the latest enhancements to out-of-the-box document processing – with little to no training required
Get an exclusive demo of the new family of UiPath LLMs – GenAI models specialized for processing different types of documents and messages
This is a hands-on session specifically designed for automation developers and AI enthusiasts seeking to enhance their knowledge in leveraging the latest intelligent document processing capabilities offered by UiPath.
Speakers:
👨🏫 Andras Palfi, Senior Product Manager, UiPath
👩🏫 Lenka Dulovicova, Product Program Manager, UiPath
The Art of the Pitch: WordPress Relationships and SalesLaura Byrne
Clients don’t know what they don’t know. What web solutions are right for them? How does WordPress come into the picture? How do you make sure you understand scope and timeline? What do you do if sometime changes?
All these questions and more will be explored as we talk about matching clients’ needs with what your agency offers without pulling teeth or pulling your hair out. Practical tips, and strategies for successful relationship building that leads to closing the deal.
Kubernetes & AI - Beauty and the Beast !?! @KCD Istanbul 2024Tobias Schneck
As AI technology is pushing into IT I was wondering myself, as an “infrastructure container kubernetes guy”, how get this fancy AI technology get managed from an infrastructure operational view? Is it possible to apply our lovely cloud native principals as well? What benefit’s both technologies could bring to each other?
Let me take this questions and provide you a short journey through existing deployment models and use cases for AI software. On practical examples, we discuss what cloud/on-premise strategy we may need for applying it to our own infrastructure to get it to work from an enterprise perspective. I want to give an overview about infrastructure requirements and technologies, what could be beneficial or limiting your AI use cases in an enterprise environment. An interactive Demo will give you some insides, what approaches I got already working for real.
Search and Society: Reimagining Information Access for Radical FuturesBhaskar Mitra
The field of Information retrieval (IR) is currently undergoing a transformative shift, at least partly due to the emerging applications of generative AI to information access. In this talk, we will deliberate on the sociotechnical implications of generative AI for information access. We will argue that there is both a critical necessity and an exciting opportunity for the IR community to re-center our research agendas on societal needs while dismantling the artificial separation between the work on fairness, accountability, transparency, and ethics in IR and the rest of IR research. Instead of adopting a reactionary strategy of trying to mitigate potential social harms from emerging technologies, the community should aim to proactively set the research agenda for the kinds of systems we should build inspired by diverse explicitly stated sociotechnical imaginaries. The sociotechnical imaginaries that underpin the design and development of information access technologies needs to be explicitly articulated, and we need to develop theories of change in context of these diverse perspectives. Our guiding future imaginaries must be informed by other academic fields, such as democratic theory and critical theory, and should be co-developed with social science scholars, legal scholars, civil rights and social justice activists, and artists, among others.
Neuro-symbolic is not enough, we need neuro-*semantic*Frank van Harmelen
Neuro-symbolic (NeSy) AI is on the rise. However, simply machine learning on just any symbolic structure is not sufficient to really harvest the gains of NeSy. These will only be gained when the symbolic structures have an actual semantics. I give an operational definition of semantics as “predictable inference”.
All of this illustrated with link prediction over knowledge graphs, but the argument is general.
How world-class product teams are winning in the AI era by CEO and Founder, P...
Theory of AC and DC Meter Testing
1. Theory of AC and
DC Meter Testing
Prepared by Tom Lawton, TESCO
For North Carolina Electric Meter School
Advanced
Tuesday, June 15, 2021 at 9:30 a.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
Westinghouse
• 1884 – George Westinghouse establishes
the Union Switch & Signal Co. in
Pittsburgh, PA
• Buys the U.S. rights to a transformer
patented in Europe
• The company reorganizes as the
Westinghouse Electric and Manufacturing
Company
• William Stanley joins the company as the
chief electrical engineer and Oliver B.
Shallenberger resigns as an officer in the
U.S. Navy to work under him as the chief
electrician. George Westinghouse
7. 7
AC Starts to Win
• Stanley and Schallenberger: They refine the transformer design and in
1886 Stanley demonstrates the first complete system of high voltage AC
transmissions including generators, transformers, and high voltage
transmission lines.
• AC had none of the issues of DC (voltage drop in long lines and a lack of
an easy way to increase or decrease the voltage). However there was no
meter that could accurately record the usage of electricity on AC circuits.
William Stanley, Jr. Oliver Schallenberger
8. 8
Thomas Edison - 1889
"Fooling around with
alternating current is just
a waste of time. Nobody
will use it, ever."
- Thomas Edison, 1889
9. 9
1888: A Young Serb Named Никола Тесла (Nicola
Tesla) Meets George Westinghouse
Nicola Tesla,
"The Wizard of
The West"
1893: World’s Fair Chicago
lighted by Westinghouse / Tesla
1882:
Induction
Motor
1888: Westinghouse,
American entrepreneur
and engineer meets
Tesla
10. 10
1893: Westinghouse Awarded the Contract for
Powerhouse at Niagara Falls
Edward Dean Adams power station at Niagara, with ten 5,000-horsepower
Tesla/Westinghouse AC generators — the culmination of Tesla's dream.
(Courtesy Smithsonian Institution)
11. 11
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.
12. 12
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)
13. 13
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).
14. 14
AC Theory – Sine Wave
)
2
sin(
ft
V
V pk
0
)
2
sin(
2
ft
V
V rms
120
rms
V
169
pk
V
15. 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
)
2
sin(
10 ft
V
)
30
2
sin(
10
ft
I
Here current LAGS voltage.
16. 16
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.
17. 17
AC Theory – RMS
• For DC voltage to equal AC voltage we need
dt
ft
V
R
R
Vdc
)
2
(
sin
1 2
2
0
2
R
V
R
Vdc
2
2
0
2
DC
V
V 2
0
18. AC Theory - RMS
)
sin(
68
.
169
)
sin(
2
120 t
t
V
(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
19. 19
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
)
2
sin(
2
)
(
ft
V
t
V DC
21. 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
R
Vrms
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.
22. 22
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
L
Vrms
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.
23. 23
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 C
Vrms
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.
24. 24
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.
25. 25
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.
26. 26
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
)
2
sin(
2
120 ft
V
)
2
sin(
2
96 ft
I
)
2
(
sin
23040 2
ft
P
For a resistive load: ))
2
cos(
1
(
)
(
sin
2 2
t
VI
t
VI
vi
p
P = 11520 Watts
27. 27
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
)
2
sin(
2
120 ft
V
)
90
2
sin(
2
96
ft
I )
2
sin(
11520 ft
P
For an inductive load:
P = 0 Watts
)
2
sin(
)
90
sin(
)
sin(
2 t
VI
t
t
VI
vi
p
28. 28
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
)
2
sin(
2
120 ft
V
)
90
2
sin(
2
96
ft
I )
2
sin(
11520 ft
P
For an capacitive load:
P = 0 Watts
)
2
(
)
90
(
)
(
2 t
VISin
t
Sin
t
VISin
vi
p
29. 29
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.
30. 30
AC Theory – Complex Circuits
AC
C
Vrms
Irms
R
L
2
2
)
1
(
C
L
R
V
I
Amplitude (Current)
R
C
L )
1
(
arctan
Phase (Current)
VC
V
VL
VC
VR
31. 31
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
)
2
sin(
2
120 ft
V
)
60
2
sin(
2
96
ft
I
)
60
4
cos(
23040
19953
))
60
4
cos(
)
60
(cos(
23040
ft
ft
VI
P
32. 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(
33. 33
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
34. 34
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.
36. 36
AC Theory - Phasors
• An easier way to view AC data
CURRENT
VOLTAGE
A
B
C
Va 0°
I a 0°
Vb 120°
I b 120°
Vc 240°
I c 240°
THE VECTOR
DIAGRAM
37. 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.
)
30
2
sin(
2
5
.
2
ft
I
)
0
2
sin(
2
120
ft
V
CURRENT
VOLTAGE
A
Va 0°
I a 30°
THE VECTOR
DIAGRAM
38. 38
AC Theory - Phasors
Phasors are particularly useful in poly-phase situations
CURRENT
VOLTAGE
A
B
C
Va 0°
I a 12°
Vb 120°
I b 126°
Vc 240°
I c 247°
THE VECTOR
DIAGRAM
39. 39
New Energy Definitions
• At the moment there is no non-sinusoidal
definition for VA
• New ANSI Standard coming soon
C12.31
44. 44
What about DC?
• We have had DC Metering since the
1870’s.
• The first patented meter was a DC meter
in 1872, six years before the first AC
meter.
45. 45
Elihu Thomson
• 1889 Thomson introduced his
recording wattmeter (AC or DC – a
commutator-type meter).
• This was the first true watthour meter,
and it was an immediate commercial
success, many utilities adopting it as
their "standard" model.
• Although this meter was initially
designed for use on AC circuits, it
worked equally well with the DC
circuits in use at the time.
• The introduction and rapid acceptance
of induction-type watthour meters in
the late 1890s relegated the use of this
commutator-type meter to DC circuits.
46. 46
DC Theory?
No need for new definitions. Power is
simply VA. If we can measure the
fundamental Volt and the fundamental Amp
then we can create a Standard to measure
against and can effectively test our DC
meter.
47. 47
What about DC?
• There are still a number of DC meters out on our systems, primarily
in the larger, older urban areas such as San Francisco and New
York City.
• There has been no effective way to test these legacy meters for
some time. This is shortcoming was highlighted as new DC
metering applications have begun to make an appearance on the
grid and are demanding we find a solution (e.g. DC superchargers)
• Using labs with traceable Voltage sources and measurement
capabilities and traceable Current sources and measurement
capabilities we are now starting to do this.
48. 48
ANSI C12.32
• As always, the theory is only the start. We now need to take this
theory and create a practical process. For AC Meters we have been
using ANSI C12.1 for many years to guide us on how to move from
theory to practice.
• We have never had a comparable Standard for DC Metering
• ANSI Standard ANSI C12.32 for Electricity Meters for the
Measurement of DC Energy has been developed over the past
several years and is actively being balloted and is expected to be
released in 2022.
• This Standard lays out the tests, the definitions, the acceptable
performance levels for accuracy as well as functional testing.
• Definitions are given and the practical means of type testing as well
as acceptance testing are given.
49. 49
Questions and Discussion
Tom Lawton
President
tom.lawton@tescometering.com
TESCO – The Eastern Specialty Company
Bristol, PA
215-228-0500
This presentation can also be found under Meter Conferences and
Schools on the TESCO website: www.tescometering.com
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