This document discusses transformer-rated metering fundamentals, including:
- Transformer-rated meters measure current through current transformers and sometimes voltage transformers, unlike self-contained meters which connect directly to the load.
- Blondel's theorem states that total power in a polyphase system can be measured using N-1 meters connected between each line and a common point.
- Meeting Blondel's theorem ensures accurate power measurements under all conditions, while violations may cause errors if voltage and current are not balanced.
- Examples show how to apply Blondel's theorem correctly for 3-phase 4-wire systems.
Four quadrant metering can be used to understand individually or collectively:
Real Power consumed by the end user
Apparent Power delivered by the utility
Real Power delivered to the utility by an end user’s generation source
Apparent Power generated by the end user’s generation source
Having these measurements allows for the calculation of Reactive Power, VA and VARS as well as providing kWh for billing purposes.
This presentation discusses the differences between self-contained and transformer or instrument rated meter sites; transformer rated meter forms; test switches and CTs; meter accuracy testing in the field; checking the health of your CTs and PTs; and Site Verification. This presentation was given at the MEUA Meter School. 03/03/20
Four quadrant metering can be used to understand individually or collectively:
Real Power consumed by the end user
Apparent Power delivered by the utility
Real Power delivered to the utility by an end user’s generation source
Apparent Power generated by the end user’s generation source
Having these measurements allows for the calculation of Reactive Power, VA and VARS as well as providing kWh for billing purposes.
This presentation discusses the differences between self-contained and transformer or instrument rated meter sites; transformer rated meter forms; test switches and CTs; meter accuracy testing in the field; checking the health of your CTs and PTs; and Site Verification. This presentation was given at the MEUA Meter School. 03/03/20
This presentation was for an Advanced Session at North Carolina Meter School and discussed CT functionality Basics, Terminology and Specifications, Ratio Testing, Burden Testing, Admittance Testing, and Demag Functions.
Learn the differences between self-contained and transformer or instrument rated meter sites, test switches and CTs, Blondel’s Theorem, meter accuracy testing, site verification, and more! This presentation was given at MEUA Meter School. 03.03.20
In this presentation, the topics covered include: differences between self contained and transformer or instrument rated meter sites; transformer rated meter forms; test switches and CT's; Blondel's Theorem and why this matters to us in metering; meter accuracy testing in the field; checking the health of your CT's and PT's; and site verification.
In this presentation, the topics covered include: differences between self contained and transformer or instrument rated meter sites; transformer rated meter forms; test switches and CT's; Blondel's Theorem and why this matters to us in metering; meter accuracy testing in the field; checking the health of your CT's and PT's; and site verification. This presentation was given at the Mississippi Electric Meter School on October 10, 2018.
This presentation will cover the basics and differences between self-contained and transformer or instrument rated meter sites. Also discussed are transformer rated meter forms, test switches and CT's, Blondel's Theorem and why this matters to metering, meter accuracy testing in the field, checking the health of your CT's and PT's, and Site Verification (and not just meter testing).
This presentation discusses self-contained vs. transformer rated CTs, functions and terminology, CT testing, ratio testing, burden testing, and more. 06/26/2019
This presentation covers the basics of self-contained and transformer rated meter sites, transformer rated meter forms, test switches and CTs, Blondel's Theorom, meter accuracy testing in the field, and site verification. This presentation was given during the PREA Meter School in March 2019.
Did you know vehicle manufacturers have announced over 100 electric vehicle models are to be introduced by 2024? This presentation was given at the Southeastern Distribution Apparatus School in Auburn, AL and covers Electric Vehicle Service Equipment (EVSE) and the testing of Electric Vehicle stations. This presentation covers types of EVSEs, market growth, regulatory environment and type approval and testing.
Why test on site? The utility wants to receive full payment for the services it provides. The customer wants to be billed fairly to get the lowest bill possible. This set of infographics is to facilitate the understanding of the need to test electricity meters and practically show how testing should be done. Intended for technicians, engineers, students, utilities staff and all interested in reliable energy measurement. Many definitions and examples are simplified to get clear way of reliable test results obtaining. Although the author tried to avoid errors, they can probably be found in the content, hence any comments are welcomed.
This presentation will cover the basics and differences between self-contained and transformer or instrument rated meter sites. Also discussed are transformer rated meter forms, test switches and CT's, Blondel's Theorem and why this matters to metering, meter accuracy testing in the field, checking the health of your CT's and PT's, and Site Verification (and not just meter testing).
Calmet Ltd. produces sophisticated testing equipment for Energy Meter and Power Quality Analyzers testing. There are both: single and three phase sources and high accuracy reference energy meters. Portable working standards enables testing on site energy meters and current transformers.
Learning meter forms is as easy as 1S-2S-3S! You’ll learn the most common metering forms and how they are used. This presentation also dives into Blondel’s Theorem and how it is used to determine what type of meter to install at different services.
This presentation was given at the PREA Meter School and gives an introduction to transformer rated metering including meter forms, test switches, CTs, Blondel's Theorem, site verification and more. 03/10/20
This presentation was for an Advanced Session at North Carolina Meter School and discussed CT functionality Basics, Terminology and Specifications, Ratio Testing, Burden Testing, Admittance Testing, and Demag Functions.
Learn the differences between self-contained and transformer or instrument rated meter sites, test switches and CTs, Blondel’s Theorem, meter accuracy testing, site verification, and more! This presentation was given at MEUA Meter School. 03.03.20
In this presentation, the topics covered include: differences between self contained and transformer or instrument rated meter sites; transformer rated meter forms; test switches and CT's; Blondel's Theorem and why this matters to us in metering; meter accuracy testing in the field; checking the health of your CT's and PT's; and site verification.
In this presentation, the topics covered include: differences between self contained and transformer or instrument rated meter sites; transformer rated meter forms; test switches and CT's; Blondel's Theorem and why this matters to us in metering; meter accuracy testing in the field; checking the health of your CT's and PT's; and site verification. This presentation was given at the Mississippi Electric Meter School on October 10, 2018.
This presentation will cover the basics and differences between self-contained and transformer or instrument rated meter sites. Also discussed are transformer rated meter forms, test switches and CT's, Blondel's Theorem and why this matters to metering, meter accuracy testing in the field, checking the health of your CT's and PT's, and Site Verification (and not just meter testing).
This presentation discusses self-contained vs. transformer rated CTs, functions and terminology, CT testing, ratio testing, burden testing, and more. 06/26/2019
This presentation covers the basics of self-contained and transformer rated meter sites, transformer rated meter forms, test switches and CTs, Blondel's Theorom, meter accuracy testing in the field, and site verification. This presentation was given during the PREA Meter School in March 2019.
Did you know vehicle manufacturers have announced over 100 electric vehicle models are to be introduced by 2024? This presentation was given at the Southeastern Distribution Apparatus School in Auburn, AL and covers Electric Vehicle Service Equipment (EVSE) and the testing of Electric Vehicle stations. This presentation covers types of EVSEs, market growth, regulatory environment and type approval and testing.
Why test on site? The utility wants to receive full payment for the services it provides. The customer wants to be billed fairly to get the lowest bill possible. This set of infographics is to facilitate the understanding of the need to test electricity meters and practically show how testing should be done. Intended for technicians, engineers, students, utilities staff and all interested in reliable energy measurement. Many definitions and examples are simplified to get clear way of reliable test results obtaining. Although the author tried to avoid errors, they can probably be found in the content, hence any comments are welcomed.
This presentation will cover the basics and differences between self-contained and transformer or instrument rated meter sites. Also discussed are transformer rated meter forms, test switches and CT's, Blondel's Theorem and why this matters to metering, meter accuracy testing in the field, checking the health of your CT's and PT's, and Site Verification (and not just meter testing).
Calmet Ltd. produces sophisticated testing equipment for Energy Meter and Power Quality Analyzers testing. There are both: single and three phase sources and high accuracy reference energy meters. Portable working standards enables testing on site energy meters and current transformers.
Learning meter forms is as easy as 1S-2S-3S! You’ll learn the most common metering forms and how they are used. This presentation also dives into Blondel’s Theorem and how it is used to determine what type of meter to install at different services.
This presentation was given at the PREA Meter School and gives an introduction to transformer rated metering including meter forms, test switches, CTs, Blondel's Theorem, site verification and more. 03/10/20
This presentation covers the differences between self contained and transformer or instrument rated meter sites, transformer rated meter forms, test switches and CT's, Blondel's Theorem and why it matters to metering, meter accuracy testing in the field, checking the health of your CT's and PT's, and site verification (not just meter testing).
This presentation covers differences between self-contained and instrument or transformer rated sites; transformer rated meter forms; test switches and CTs; Blondel's Theorem; meter accuracy testing; checking the health of your CTs and PTs; and site verification (and not just meter testing). This presentation was given at the PREA Meter School. 03/10/20.
A detailed presentation on Power meters which includes watt meter , poly phase power measurement , VAR meter, Energy (kilo-watt/hour) meter ,power factor meter
Learn the differences between self-contained and transformer or instrument rated meter sites, test switches and CTs, Blondel's Theorem, meter accuracy testing, site verification, and more! 01/29/2019
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.
Come join the area's leading power quality experts as we demonstrate and replicate common power quality issues, problems and solutions in today's industrial and commercial electrical environments.
Why test on site? The utility wants to receive full payment for the services it provides. The customer wants to be billed fairly to get the lowest bill possible. This set of infographics is to facilitate the understanding of the need to test electricity meters and practically show how testing should be done. Intended for technicians, engineers, students, utilities staff and all interested in reliable energy measurement. Many definitions and examples are simplified to get clear way of reliable test results obtaining. Although the author tried to avoid errors, they can probably be found in the content, hence any comments are welcomed.
Power measurement is a valid technique to measure that how much the power is being transmitted through the entire system.
In this presentation you will estimate and understand the following objectives
Wattmeter as a device
Power measurement techniques
Classical based history
Construction of wattmeter
Working of Wattmeter
Power measurement of direct and indirect way
Power measurement in three phase applications
Applications of Wattmeter
Alt. GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using ...James Anderson
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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
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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: The Art of Triggers and Actions in FMESafe Software
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We’ll kick things off by showcasing the most commonly used event-based triggers, introducing you to various automation workflows like manual triggers, schedules, directory watchers, and more. Plus, see how these elements play out in real scenarios.
Whether you’re tweaking your current setup or building from the ground up, this session will arm you with the tools and insights needed to transform your FME usage into a powerhouse of productivity. Join us to discover effective strategies that simplify complex processes, enhancing your productivity and transforming your data management practices with FME. Let’s turn complexity into clarity and make your workspaces work wonders!
GridMate - End to end testing is a critical piece to ensure quality and avoid...ThomasParaiso2
End to end testing is a critical piece to ensure quality and avoid regressions. In this session, we share our journey building an E2E testing pipeline for GridMate components (LWC and Aura) using Cypress, JSForce, FakerJS…
Sudheer Mechineni, Head of Application Frameworks, Standard Chartered Bank
Discover how Standard Chartered Bank harnessed the power of Neo4j to transform complex data access challenges into a dynamic, scalable graph database solution. This keynote will cover their journey from initial adoption to deploying a fully automated, enterprise-grade causal cluster, highlighting key strategies for modelling organisational changes and ensuring robust disaster recovery. Learn how these innovations have not only enhanced Standard Chartered Bank’s data infrastructure but also positioned them as pioneers in the banking sector’s adoption of graph technology.
Securing your Kubernetes cluster_ a step-by-step guide to success !KatiaHIMEUR1
Today, after several years of existence, an extremely active community and an ultra-dynamic ecosystem, Kubernetes has established itself as the de facto standard in container orchestration. Thanks to a wide range of managed services, it has never been so easy to set up a ready-to-use Kubernetes cluster.
However, this ease of use means that the subject of security in Kubernetes is often left for later, or even neglected. This exposes companies to significant risks.
In this talk, I'll show you step-by-step how to secure your Kubernetes cluster for greater peace of mind and reliability.
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
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In this work, we equipped AFL, a popular fuzzer, with DIAR and examined two critical Linux libraries -- Libxml's xmllint, a tool for parsing xml documents, and Binutil's readelf, an essential debugging and security analysis command-line tool used to display detailed information about ELF (Executable and Linkable Format). Our preliminary results show that AFL+DIAR does not only discover new paths more quickly but also achieves higher coverage overall. This work thus showcases how starting with lean and optimized seeds can lead to faster, more comprehensive fuzzing campaigns -- and DIAR helps you find such seeds.
- These are slides of the talk given at IEEE International Conference on Software Testing Verification and Validation Workshop, ICSTW 2022.
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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.
Unlocking Productivity: Leveraging the Potential of Copilot in Microsoft 365, a presentation by Christoforos Vlachos, Senior Solutions Manager – Modern Workplace, Uni Systems
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• How a better user experience drives measurable business benefits
• How to get started with SAP Fiori today
• How SAP Fiori elements accelerates application development
• How SAP Build Code includes SAP Fiori tools and other generative artificial intelligence capabilities
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• Communication Mining Overview
• Why is it important?
• How can it help today’s business and the benefits
• Phases in Communication Mining
• Demo on Platform overview
• Q/A
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.
2. 2
January 28, 2019
Atlanta, GA
Transformer-Rated & Self-Contained
Metering Fundamentals
Prepared by Tom Lawton, TESCO
The Eastern Specialty Company
TESCO Tuesdays
October 6, 2020
3. 3
Topics we will be covering
• The Basics- Differences Between Self
Contained and Transformer or Instrument
Rated Meter Sites
• Transformer Rated Meter Forms
• Test Switches and CT’s
• Blondel’s Theorem and why this matters to
us in metering
• Meter Accuracy Testing in the Field
• Checking the Health of your CT’s and PT’s
• Site Verification and not just meter testing
4. 4
Self Contained Metering
•Typically found in residential
metering
•Meters are capable of handling
the direct incoming amperage
•Meter is connected directly to
the load being measured
•Meter is part of the circuit
•When the meter is removed
from the socket, power to the
customer is interrupted
5. 5
Meters Through the Years
Induction Meter Duncan Meter Meter from 1960’s
Meter from 80’s and 90’s 2000 to Present
6. 6
Back to Basics: Electrical Laws
Ohms Law
Voltage = Current times Resistance
V = I X R
THE MOST USEFUL AND THE MOST
FUNDAMENTAL OF THE ELECTRICAL LAWS
7. 7
Basic Concepts: Electricity and Water
Comparing Electricity to Water flowing from a hose
■ Voltage is the equivalent of the pressure in the hose
■ Current is water flowing through a hose (coulombs/sec vs
gal/sec). The water in a system is the “charge” (coulombs)
■ Impedance(Resistance) is the size of the hose. The nozzle
would provide a change in resistance.
■ Power is how fast water flows from a pipe (gallons per minute vs
kilowatts). Power is a rate of energy consumption
10. 10
Basic Electrical Laws
♦ Ohms Law Examples
■ If V = 20 volts and I = 5 amperes what is the resistance?
R = V / I = 20 / 5 = 4 ohms
■ If R = 20 ohms and V = 120 volts what is the current?
I = V / R = 120 / 20 = 6 amps
■ If I = 10 amperes and R = 24 ohms what is the voltage?
V = I x R = 10 x 24 = 240 volts
■ Problem: If V = 240 volts and R = 6 ohms what is the current?
I = V / R = 240 / 6 = 40 amps
12. 12
Basic Electrical Laws
♦ Power = Voltage x Current = V x I = I2R = V2/R
■ If V = 20 volts and I = 8 amperes what is the power?
P = V x I = 20 x 8 = 160 watts
■ If R = 5 ohms and V = 120 volts what is the power?
P = V2/R = 120 x 120 / 5 = 2880 watts
■ If I = 10 amperes and R = 20 ohms what is the power?
P = I2R = 10 x 10 x 20 = 2000 watts
1 kilowatt (kW) = 1,000 watts
1 megawatt (MW) = 1,000,000 watts
13. 13
Basic AC Theory
What is VA?
Power was measured in Watts. Power does useful work.
The power that does useful work is referred to as
“Active Power.”
VA is measured in Volt-Amperes. It is the capacity
required to deliver the Power. It is also referred to as the
“Apparent Power.”
Power Factor = Active Power / Apparent Power
VA = E x I
PF = W/VA
14. 14
Basic Meter Math
Power – VA
For a 120 Volt service drawing 60 Amps at 1.00 PF
How much power is being drawn?
Power = 120 x 60 x 1.00 = 7,200 Watts
How many VA are being drawn?
VA = 120 x 60 = 7,200 Volt Amperes
15. 15
Basic AC Theory
Power – The Simple View
E = Voltage (rms)
I = Current (rms)
PF = Power Factor
Power = Watts = E x I x PF
Power is sometimes
referred to as Demand
Sinusoidal
Waveforms
Only
NO
Harmonics
For a 120 Volt service drawing
13 Amps at Unity (1.0) PF,
how much power is being drawn?
Power = 120 x 13 x 1.0 = 1560 Watts
17. 17
Basic Meter Math
Power – The Simple View
For a 120 Volt service drawing
13 Amps at 0.866 PF,
how much power is being drawn?
Power = 120 x 13 x 0.866 = 1351 Watts
For a 480 Volt service drawing
156 Amps at 0.712 PF,
how much power is being drawn?
Power = 480 x 156 x 0.712 = 53,315 Watts
18. 18
Basic AC Theory
Power – The Simple View
In the previous example we had:
Power = 480 x 156 x 0.712 = 53,315 Watts
Normally we don’t talk about Watts, we speak in Kilowatts
1000 Watts = 1 Kilowatt = 1 kW
Watts / 1000 = Kilowatts
For a 480 Volt service drawing
156 Amps at Unity (0.712) PF,
how many Kilowatts are being drawn?
Power = 480 x 156 x 0.712 / 1000 = 53.315 kW
19. 19
Basic AC Theory
Energy – What We Sell
If power is how fast water flows from a pipe,
then energy is how much water we have in a bucket
after the water has been flowing for a specified time.
Energy = Power x Time
1 kW for 1 Hour = 1 Kilowatt-Hour = 1 kWh
Energy (Wh) = E x I x PF x T
where T = time in hours
Energy (kW) = (E x I x PF / 1000) x T
20. 20
Basic Meter Math
Energy – What We Sell
For a 120 Volt service drawing 45 Amps at a
Power Factor of 0.9 for 1 day,
how much Energy (kWh) has been used?
Energy = (120 x 45 x 0.9 / 1000) x 24 = 116.64 kWh
For a 240 Volt service drawing 60 Amps at a
Power Factor of 1.0 for 5.5 hours,
how much Energy (kWh) has been used?
Energy = (240 x 60 x 1.0 / 1000) x 5.5 = 79.2 kWh
21. 21
Basic Meter Math
Energy – What We Sell
For a 120 Volt service drawing 20 Amps at a
Power Factor of 0.8 from 8:00AM to 6:00PM,
and 1 Amp at PF=1.0 from 6:00PM to 8:00AM
how much Energy (kWh) has been used?
8:00AM to 6:00PM = 10 hours
6:00PM to 8:00AM = 14 hours
Energy = (120 x 20 x 0.8 / 1000) x 10 = 19.2 kWh
Energy = (120 x 1 x 1 / 1000) x 14 = 1.68 kWh
Energy = 19.2 kWh + 1.68 kWh = 20.88 kWh
22. 22
Basic Energy Formula
• The essential specification of a watthour meter’s measurement
is given by the value
Kh [ Watthours per disk revolution ]
• The watthour meter formula is as follows:
srevolutiondisk
revolutiondisk
watthours
Watthours nKE h *
24. 24
TESCO/Georgia Power 2017 Caribbean Meter School
Fundamentals of Polyphase Field Meter Testing and Site Verification
Full Load
Light Load
Power Factor
Meter Accuracy Testing
Meter Accuracy
Testing in a Nutshell
25. 25
Transformer Rated Metering
• Meter measures scaled down
representation of the load.
• Scaling is accomplished by the use
of external current transformers
(CTs) and sometimes voltage
transformers or PTs).
• The meter is NOT part of the circuit
• When the meter is removed from
the socket, power to the customer
is not effected.
26. 26
9S Meter Installation with 400:5 CT’s
400A
400A
400A
LOAD
5A 5A 5A
SOURCE
PHASE A
PHASE B
PHASE C
The Basic Components
28. 28
Current Transformer Testing System &
Voltage Transformer Testing System
Knopp Voltage Transformer
Testing System
Knopp Current Transformer
Testing System
29. 29
Fundamentals of Polyphase Field Meter
Testing and Site Verification
Current Transformers Conceptual
Representation
Real, with core losses
Ideal. No losses
30. 30
Fundamentals of Polyphase Field Meter
Testing and Site Verification
Functionality with Burden Present on the Secondary Loop
PHASE A
• Some burden will always be
present – junctions, meter
coils, test switches, cables,
etc.
• CT’s must be able to
maintain an accurate ratio
with burden on the
secondary.
31. 31
Fundamentals of Polyphase Field Meter
Testing and Site Verification
Functionality with Burden Present on the Secondary Loop
Example Burden Spec:
0.3% @ B0.1, B0.2, B0.5
or
There should be less than the 0.3%
change in secondary current from initial
(“0” burden) reading, when up to 0.5 Ohms
of burden is applied
Fundamentals of Polyphase Field Meter
Testing and Site Verification
32. 32
Fundamentals of Polyphase Field Meter
Testing and Site Verification
Functionality with Burden Present on the Secondary Loop
0.3% @ B0.1, B0.2, B0.5
0.0000
1.0000
2.0000
3.0000
4.0000
5.0000
6.0000
0 2 4 6 8
Initial Reading = 5Amps
0.3% x 5A = 0.015A
5A – 0.015 = 4.985A
Burden Reading
0 5.0000
0.1 4.9999
0.2 4.9950
0.5 4.9900
1 4.9800
2 4.9500
4 4.0000
8 0.8000
33. 33
Ratio of Primary Current to Secondary Current
PHASE A
SOURCE LOAD
400A
400A
400A
5A5A
Calculate Ratio
Fundamentals of Polyphase Field Meter
Testing and Site Verification
35. 35
Three Phase Power
Blondel’s Theorem
The theory of polyphase watthour metering was first set forth on a scientific
basis in 1893 by Andre E. Blondel, engineer and mathematician. His theorem
applies to the measurement of real power in a polyphase system of any
number of wires. The theorem is as follows:
- If energy is supplied to any system of conductors
through N wires, the total power in the system is given
by the algebraic sum of the readings of N wattmeters, so
arranged that each of the N wires contains one current
coil, the corresponding voltage coil being connected
between that wire and some common point. If this
common point is on one of the N wires, the
measurement may be made by the use of N-1
wattmeters.
36. 36
Three Phase Power
Blondel’s Theorem
• Simply – We can measure the power in a
N wire system by measuring the power in
N-1 conductors.
• For example, in a 4-wire, 3-phase system
we need to measure the power in 3
circuits.
37. 37
Three Phase Power
Blondel’s Theorem
• If a meter installation meets Blondel’s
Theorem then we will get accurate power
measurements under all circumstances.
• If a metering system does not meet
Blondel’s Theorem then we will only get
accurate measurements if certain
assumptions are met.
38. 38
Blondel’s Theorem
• Three wires
• Two voltage measurements with
one side common to Line 2
• Current measurements on lines
1 & 3.
This satisfies Blondel’s
Theorem.
39. 39
Blondel’s Theorem
• Four wires
• Two voltage measurements to
neutral
• Current measurements on lines 1 &
3. How about line 2?
This DOES NOT satisfy Blondel’s
Theorem.
40. 40
Blondel’s Theorem
• In the previous example:
– What are the “ASSUMPTIONS”?
– When do we get errors?
• What would the “Right Answer” be?
• What did we measure?
)cos()cos()cos( cccbbbaaasys IVIVIVP
)]cos()cos([)]cos()cos([ bbcccbbaaasys IIVIIVP
41. 41
Blondel’s Theorem
• Phase B power would be:
– P = Vb Ib cosθ
• But we aren’t measuring Vb
• What we are measuring is:
– IbVacos(60- θ) + IbVccos(60+ θ)
• cos(α + β) = cos(α)cos(β) - sin(α)sin(β)
• cos(α - β) = cos(α)cos(β) + sin(α)sin(β)
• So
43. 43
Blondel’s Theorem
• If Va ≠ Vb ≠ Vc then the error is
• %Error =
-Ib{(Va+Vc)/(2Vb) - (Va-Vc) 0.866sin(θ)/(Vbcos(θ))
How big is this in reality? If
Va=117, Vb=120, Vc=119, PF=1 then E=-1.67%
Va=117, Vb=116, Vc=119, PF=.866 then E=-1.67%
46. 46
The Importance of CT Testing in the Field
• One transformer in three wired
backwards will give the customer a
bill of 1/3rd the actual bill.
• One broken wire to a single
transformer will give the customer a
bill of 2/3rd the actual bill
• One dual ratio transformer
inappropriately marked in the billing
system as 400:5 instead of 800:5
provides a bill that is ½ of the actual
bill. And the inverse will give a bill
double of what should have been
sent. Both are lose-lose situations
for the utility.
47. 47
The Importance of CT Testing in the Field
(continued)
•Cross Phasing (wiring errors)
•Loose or Corroded Connections
•CT Mounted Backwards
•CT’s with Shorted Turns
•Wrong Selection of Dual Ratio CT
•Detect Magnetized CT’s
•Burden Failure in Secondary Circuit
•Open or Shorted Secondary
•Mislabeled CT’s
•Ensures all Shorting Blocks have been Removed
48. 48
Potential list of tasks to be completed during a Site
Verification of a Transformer Rated Metering Site
• Double check the meter number, the location the test result and the meter record
• Perform a visual safety inspection of the site. This includes utility and customer equipment. Things
to look for include intact down ground on pole, properly attached enclosure, unwanted voltage on
enclosure, proper trimming and site tidiness (absence of discarded seals, etc.)
• Visually inspect for energy diversions (intentional and not). This includes broken or missing wires,
jumpers, open test switch, unconnected wires and foreign objects on meters or other metering
equipment. Broken or missing wires can seriously cause the under measurement of energy. A
simple broken wire on a CT or VT can cause the loss of 1/3 to 1/2 of the registration on either 3
element or 2 element metering, respectively.
• Visually check lightning arrestors and transformers for damage or leaks.
• Check for proper grounding and bonding of metering equipment. Poor grounding and bonding
practices may result in inaccurate measurements that go undetected for long periods of time.
Implementing a single point ground policy and practice can reduce or eliminate this type of issue.
• Burden test CTs and voltage check PTs.
49. 49
Site Verification Checklist (continued)
• Verify service voltage. Stuck regulator or seasonal capacitor can impact service voltage.
• Verify condition of metering control wire. This includes looking for cracks in insulation, broken
wires, loose connections, etc.
• Confirm we have a Blondel compliant metering set up
• Compare the test switch wiring with the wiring at the CTs and VTs. Verify CTs and VTs not cross
wired. Be sure CTs are grounded in one location (test switch) only.
• Check for bad test switch by examining voltage at the top and bottom of the switch. Also verify
amps using amp probe on both sides of the test switch. Verify neutral connection to cabinet
(voltage).
• Check rotation by closing in one phase at a time at the test switch and observing the phase
meter for forward rotation. If forward rotation is not observed measurements may be significantly
impacted as the phases are most likely cancelling each other out.
• Test meter for accuracy. Verify demand if applicable with observed load. If meter is performing
compensation (line and/or transformer losses) the compensation should be verified either
through direct testing at the site or by examining recorded pulse data.
• Loss compensation is generally a very small percentage of the overall measurement and would
not be caught under utilities normal high/low checks. However, the small percentages when
applied to large loads or generation can really add up overtime. Billing adjustments can easily be
in the $million range if not caught early.
50. 50
Site Verification Checklist (continued)
• Verify metering vectors. Traditionally this has been done using instruments such as a circuit
analyzer. Many solid state meters today can provide vector diagrams along with volt/amp/pf and
values using meter manufacturer software or meter displays. Many of these desired values are
programmed into the meters Alternate/Utility display. Examining these values can provide much
information about the metering integrity. It may also assist in determining if unbalanced loads are
present and if CTs are sized properly. The vendor software generally has the ability to capture both
diagnostic and vector information electronically. These electronic records should be kept in the
meter shop for future comparisons.
• If metering is providing pulses/EOI pulse to customers, SCADA systems or other meters for
totalization they also should be verified vs. the known load on the meter. If present test/inspect
isolation relays/pulse splitters for things like blown fuses to ensure they are operating properly.
• Verify meter information including meter multiplier, serial number, dials/decimals, Mp, Ke, Primary
Kh, Kr and Rate. Errors in this type of information can also cause a adverse impact on
measured/reported values.
• Verify CT shunts are all opened.
• Look for signs of excessive heat on the meter base e.g.
melted plastic or discoloration related to heat
51. 51
Site Verification: Why should we invest our
limited meter service resources here
• These customers represent a
disproportionately large amount of the overall
revenue for every utility in North America.
• For some utilities the ten percent of their
customers who have transformer rated
metering services can represent over 70% of
their overall revenue.
• While these numbers will vary from utility to
utility the basic premise should be the same
for all utilities regarding where Meter
Services should focus their efforts
• This is perhaps one of the larger benefits that
AMI can provide for our Utilities – more time
to spend on C&I metering and less on
residential
Easy Answer: Money.
52. 52
Periodic Site Inspections…..
….Can Discover or Prevent:
• Billing Errors
• Bad Metering set-up
• Detect Current Diversion
• Identify Potential Safety Issues
• Metering Issues (issues not
related to meter accuracy)
• AMR/AMI Communications Issues
• The need for Unscheduled Truck Rolls
due to Undetected Field Related Issues
• Discrepancies between what is
believed to be at a given site versus the
actual setup and equipment at the site
53. 53
Topics we covered
• The Basics- Differences Between Self
Contained and Transformer or Instrument
Rated Meter Sites
• Transformer Rated Meter Forms
• Test Switches and CT’s
• Blondel’s Theorem and why this matters to
us in metering
• Meter Accuracy Testing in the Field
• Checking the Health of your CT’s and PT’s
• Site Verification and not just
meter testing
54. 54
Q&A and
Upcoming TESCO Tuesday Presentations
Presentation Date
OSHA Title 8 & Meter Testing Safety 10/13
Meter Test Switches 10/20
CT Testing: Theory & Practice 10/27
Ratio, Burden and Admittance 11/3
Asset & Inventory Management in the IoT Utility 2.0 World 11/10
Harmonics 11/17
Complete Site Testing 12/1
Electric Vehicle Trends & Calibration of Commercial Chargers 12/8
Streetlights & 5G Metering and Testing 12/15
Sign up: tescometering.com/tescotuesdays
55. #TESCOTuesdays
Thanks for tuning in!
See you at the next session.
Upcoming Session:
OSHA Title 8 & Meter Testing Safety
October 13, 2020 | 11:00 AM Eastern
@tescometering
@TESCO_Metering
TESCO -The Eastern Specialty Company
TESCO -The Eastern Specialty Company