High Quality Power Transformers For Grid Reliability

© ABB BU Transformers - 1 9/26/2008

Thomas Fogelberg Head of Quality ABB Power Transformers

High Quality Power Transformers for Grid Reliability Singapore Sept 22-23, 2008

Transformers enable efficient energy transfer in society The Theworkhorses workhorses of ofthe theelectrical electrical system system

Generator Step-Up transformers

Reliability Reliabilityand and availability availabilityin in focus focus

© ABB BU Transformers - 2 -

System transformers

The Thecorrect correctuse useof ofvoltage voltage&¤t currentisisthe thekey keyto toefficiency efficiency

Energy efficiency: Optimum use of voltages & currents Process automation systems

net energy

Plant Transport automation systems systems

© ABB BU Transformers - 3 -

Process automation systems

Drive & motor systems

Building Installations

Total Totalelectrical electricalsystem system from transmission from transmissionto to distribution very efficient distribution very efficient

transport

conversion efficiency

Primary energy

Grid operation systems

Electrical energy

line losses

Transmission & Distribution

production process

Industrial Plant

motor efficiency buildings

Motors & Drives

Buildings

The Purpose of the Power Transformer = Gear Box It is the long term available “Gear Box” for production and transport of electric power which counts !! It shall always work !! The “Gear box” shall be as efficient as today, 99.6 – 99.7 % !!! The efficiency of the transformer is not the major purpose, it is to work as a gearbox over 40 years to make the electric infrastructure system efficient You get the infrastructure efficiency from “94 % to 97 %” to go from 66 to 110 kV 110 to 145 kV or 220 V

© ABB BU Transformers - 4 -

220 to 400 kV 315 to 765 kV 500 kV DC to 800 kV DC And soon on… And the “Gear Box” helps you

Reliability of Power Transformers

© ABB BU Transformers - 5 -

300 MVA 220/115/37 kV transformer

Reliability of Power Transformers

© ABB BU Transformers - 6 -

800 kV transformer

Reliability of Power Transformers

© ABB BU Transformers - 7 -

1200 MVA 400 kV Phase Shifter

Reliability of Power Transformers Engineering To Order business Concept From Unique Specification To One unique Power Transformer

© ABB BU Transformers - 8 -

This Tutorial will describe some very important aspects in the process from making a proposal (tender) to manufacture and test the final Transformer The whole power industry needs more to discuss how we can mitigate the risks from designing grids/Substations, making Transformer Specs to manufacturing/installing and maintain power transformers for over 40 years of service.

T&D Products Complexity charter Units per design < 2 Power Transformers

Volume Many unique Many Many products: Several products: products: medium products: one each low volume volume high volume

One product: very high volume

Complexity and Size Layout and Flow

Large Power Transformers Functional layout, flow extremely varied

Job Shop

GIS Substations Small Power Transformers

Batch Flow

Cellular layout, flow varied with patterns

HV Switchgear Distribution Transformers

Large Motors Line flow, operator paced, flow mostly regular Line flow, equipment paced, flow regular

Operator Paced MV & HV Breakers Line Flow

Small Motors

MV Apparatus

Machine Paced Line Flow Machining & Components LV Breakers

Continuous Flow Insulation Materials

© ABB BU Transformers - 9 -

Continuous flow: flow rigid

HV & LV Cables

ETO

ATO

STD

Types Typesof ofmanufacturing manufacturingprocesses processes

High Quality Power Transformers for Grid Reliability Agenda Market Background: The biggest Change since ever Loss Evaluations and impact on today's design Procurement processes ABB TrafoStar Technology and Design Consideration to build reliable transformers Manufacturing aspects © ABB BU Transformers - 10 -

Short Circuit Safe Design & Manufacturing&Testing Quality Management Summary remarks

World Energy Investment

72%

% " #

$ !

© ABB BU Transformers - 11 -

% &'

13% 15%

(( !

%

, $

%

(1

( .

++

/0

$

+ )*

$

1

! 22 $ 2

Transformers for reliable Power Quality

Power Transformer World Market

1994 – 2004: About 500.000 – 600.000 MVA/ year 2004 – 2007: From 750.000 to double numbers 2008 – 2015: with base demand form Asia (China,India), further demand increase to be expected ?

© ABB BU Transformers - 12 -

Huge Capacity Demand issue Material Prices increased 3 -5 times 2005 – 2007 !!!! Low or Stable Loss evaluations

Transformers for reliable Power Quality

Expected World Market ? GNP development in old and growing countries

GNP index

6

16000 USD/Capita

5 4

US CH SE DE

3

© ABB BU Transformers - 13 -

2

China India

1 0

5000

10000

15000

20000

25000

GNP/Capita

30000

35000

40000

45000

GNP/Capita

50000

Many conflicting requirements on transformers Optimization of Electric fields Magnetic fields

Losses

© ABB BU Transformers - 14 -

Temperatures Forces Ageing Noise Transport …... Requires Requiresadvanced advanced design and design andengineering engineering capabilities capabilities

Net present value of future losses 450 400

NPV of loss per year,

350

Loss per year,

300 250 200 150 100 50 0 5

10

15

20

25

© ABB BU Transformers - 15 -

Energy value 1 kW at 0,02 /kWh, 8600 h/Yr, Assume 3% energy value increase/Yr Assume 11% investment interest 2100 /kW

30

Loss Evaluations values

© ABB BU Transformers - 16 -

Example: 1 kW losses in 30 years 8600 hours per year Interest rate

0.02 /kWh

0.03 /kWh

0.04 /kWh

4%

3100

4650

6200

8%

2100

3150

4200

12%

1550

2300

3100

Examples above are for No Load losses (=8600 h/Yr) Load Loss evaluations depend on load profile per day, months etc and are therefore a varying % of the full year value

Stable values in customer specifications recently

Evaluated cost versus material content Costs Total evaluated cost Transformer cost

Evaluated loss cost

© ABB BU Transformers - 17 -

Core and Conductor mass

Higher materials prices Higher loss transformer

Conclusions: Losses vs Costs of power transformers Losses are primarily defined by the relation between materials costs and loss evaluations In recent years key materials costs have increased by a factor of 3 to 5 times Loss evaluations have changed very little Increased costs of transformers Risk for increased losses in transformers Loss evaluations determined by

© ABB BU Transformers - 18 -

Interest rate chosen for investment Expected future energy prices

What are future expectations?

Energy Energyefficiency efficiencyspecifications specificationsneeded needed

Qualitative discussion of materials utilization

"

!

© ABB BU Transformers - 19 -

!

Deregulation in the Western World ? The Electrical System Industry was working rather well up to the mid 80ies. But All actors wanted a change Rational: Interconnections through countries/states in EU and US Political: Competition in all public sectors was a motto, also in old infrastructure areas

© ABB BU Transformers - 20 -

Results: From governmental bodies to profit making companies Unbundling of Power – Transmission – Distribution Difficulties to get a collected responsibility A gradually change from long term commitments to short sighted horizons Fluctuations in electrical prices for all consumers

What can be expected in the Future ? What could happen? Purchaser drives standards lower to reduce costs – Why? Key people have personal targets based on financial performance, project budgets, see case examples: ENRON ?,Subprime loans…?

© ABB BU Transformers - 21 -

Engineering staff has been reduced to the extent that relevant experience has almost disappeared Inexperienced engineers may feel pressurised into supporting or making bad decisions

What can be expected in the Future ? Decisions made in the procurement process determine the future reliability of the transformer. Skills, Knowledge ? What is the risk? Transformers are supplied that are not fit for purpose! Long term reliability of whole family groups will be compromised Background Transformer prices/costs have risen sharply

© ABB BU Transformers - 22 -

Lead times are pushing out to three years or more But, procurement is being driven by cash conscious asset managers, or even worse, non or less technical procurement people This might lead to a pressure to cut corners to reduce costs through ignorance or lack of competence

What can be expected in the Future ? How has this developed? Reduction in technical expertise due to privatisation and regulatory driven cost pressures Senior utility managers are focused on cost and not the technical aspects

© ABB BU Transformers - 23 -

Short sight horizons

What can be expected in the Future ? What do we need to do????? Stop the problem at source How do we do that? Educate senior management of the importance of the key decision points in the procurement process Raise the profile of these key steps

© ABB BU Transformers - 24 -

Specification Design review of overall technology used in the order, consistency, experience, track records The importance of correct and accurate testing

That’s why I am here now !!!!!!!!

What can be expected in the Future ? Power Transformers are known as very Reliable Products We are going through the biggest Market change since ever

© ABB BU Transformers - 25 -

Will the Reliability numbers stay the same ?

High Quality Power Transformers for Grid Reliability Agenda Market Background: The biggest Change since ever Loss Evaluations and impact on today's design Procurement processes ABB TrafoStar Technology and Design Consideration to build reliable transformers Manufacturing aspects © ABB BU Transformers - 26 -

Short Circuit Safe Design & Manufacturing&Testing Quality Management Summary remarks

Power Transformer ETO Process The ETO Business Process of Power Transformers consists of Tender Order design Manufacturing Testing Shipping

© ABB BU Transformers - 27 -

Site erection and commissioning Lead by Quality Management Continous Improvement and R&D

ABB’s Global Transformer Plants in ETO business

SETFO Ludvika, Sweden

PLABB Lodz, Poland

DETFO Bad Honnef, Germany CATRM Varennes, Canada USTSL St.Louis, USA

ESABB Bilbao, Spain

CNCTC Chongqing, China

ESABB Cordoba, Spain TRABB Istanbul, Turkey

© ABB BU Transformers - 28 -

CNTPH Hefei, China

CNZTC Zhongshan, China THABB Bangkok, Thailand INABB Vadodara, India

Footprint Capacity Capacity Headcount

14 Plants 200.000 MVA 1.500 Units 5000 Employees

BRABB Guarulhous, Brazil

Reliability of Power Transformers Engineering To Order business Concept From Unique Specification To One unique Power Transformer

Requires on the Manufacturing side

© ABB BU Transformers - 29 -

Rigid well proven Technology Orderliness and Clarity in all procedures and documentation

ABB TrafoStar Technology TM

Common Technical Standards Common Standard drawings Common Material Specifications Common Method Provisions Common Quality System Common Tooling and Equipment Common Design rules © ABB BU Transformers - 30 -

Common Design process Common IT design tools/software

ABB TrafoStar Technology Modularization

© ABB BU Transformers - 31 -

TM

ABB TrafoStar Technology TM

A global Business Concept Basic Product Design Rules, Transformer Physics Product order design process & IT tools, Design Modules, Global Release system Methods and tools for product manufacturing Method Provisions/Instructions and Common Tooling

Material/Component specifications Planning, Capacity reservation Supply Chain Management, contracts/audits, delivery times © ABB BU Transformers - 32 -

Quality Management Testing Training, global HR interactions, Knowledge Communication Center Global Feedback System

ABB TrafoStar Technology TM

Key parts of Power Transformer technology: Product design rules physical design and dimensioning rules Order design methods and tools Manufacturing methods and tools

Product order design process & tools

engineering of specific unit produce actual unit

Methods and tools for product manufacturing

© ABB BU Transformers - 33 -

Basic product design rules , Transformer Physics •

• • • • •

Basic Dielectric Acoustics Transients and 3D Electro-Magnetic Simulations Load Losses and Thermal Performance Core Performance Short Circuit Strength

Transformer

ABB TrafoStar – Basic Dielectrics TM

What is the definition of margin? A margin must be defined towards a probability to a failure Transformers could be designed for a probability for 1 failure of 1000 units Probability for an electric breakdown

Probability for a breakdown

© ABB BU Transformers - 34 -

0,7%

10% over stress means that the risk for an electric breakdown is approximately 3/1000

0,6% 0,5% 0,4% 0,3% 0,2% 0,1% 0,0% 0,85

0,90

0,95

1,00

1,05

Relative design criterion

1,10

1,15

ABB TrafoStar – Basic Dielectrics TM

Electric breakdown strength is depending on: Material properties

E [kV/mm]

Permeability Conductivity

Direction of the stress Stress perpendicular to a surface Stress along a surface (creep stress)

The amplitude of the electric stress The duration of the stress Service stress © ABB BU Transformers - 35 -

Transients It takes some time to flash over Short duration is permitting higher stress than long

AC or DC In AC fields the stress is governed by the capacitances In DC fields the stress is governed by the resistivity

Duration

ABB TrafoStar – Basic Dielectrics TM

Material 1 Material 2

Mixing materials Materials with higher permeability are pushing the electric field in to material with lower permeability

ε1

ε2

E1 * ε1 = E2 * ε2

Oil has lower permeability than cellulose Cellulose is stronger than oil

© ABB BU Transformers - 36 -

Conductor

Stress in oil wedge

Conductor

ABB TrafoStar – Basic Dielectrics TM

© ABB BU Transformers - 37 -

Reversible

Reversible

Irreversible

ABB TrafoStar – Basic Dielectrics TM

© ABB BU Transformers - 38 -

3-D

2-D, cylindrical

ABB TrafoStar – Basic Dielectrics TM

© ABB BU Transformers - 39 -

Standardized winding end stacks which are automatically optimized by electrical design system

ABB+CEMIG 145kV Transformer

© ABB BU Transformers - 40 -

Brazil Brazil -- ABB+CEMIG ABB+CEMIG 145kV 145kV Transformer Transformer

ABB TrafoStar – Core Performance TM

Generate Accurate Calculations of: Core loss Magnitude & harmonic content of exciting current Number of cooling ducts in the core Core hot-spot and core surface hot- spot temperatures Using unique Anisotropic 2 D model of stacked cores

Meas/Calc Stdev [%]

10% 8%

PAST

6% 4% 2% 0% ABB Plant

PRESENT

Meas/Calc Stdev [%]

© ABB BU Transformers - 41 -

10% 8% 6% 4% 2% 0% ABB Plant

ABB TrafoStar – Acoustics TM

Accurate calculation of No-load level considering:

Noise -

Core steel magnetostriction characteristics Core type, core geometry, type of core joints, flux density, and frequency Sound radiation properties of the transformer

Accurate calculation of Load level considering:

Noise

Physical properties of windings and insulation

Accurate calculation of core & tank

Resonance Frequencies Allows accurate prediction of noise-level at design stage Avoids serious noise-level problems

Accurate Calculation of Frequency

Spectrum © ABB BU Transformers - 42 -

Considering No-load, Load, Current harmonics and DC magnetization

Identified and developed a number of noise reduction techniques Core steel / Tank design / Tank damping / Vibration isolation Novel technique for sound reduction in oil

ABB TrafoStar – Acoustics TM

93 MVA Transformer Size equivalent to a 250 MVA Transformer

No – Load Noise: 44.7 dBA Load Noise: 53.4 dBA Total Noise: 53.9 dBA [Typical Total Noise: 75 dBA]

65 MVA Transformer

© ABB BU Transformers - 43 -

Size equivalent to a 200 MVA Transformer

No – Load Noise at 100% V: 49.6 dBA Load Noise at 100 % I: 51.6 dBA Total Noise: 53.7 dBA [Typical Total Noise: 72 dBA]

ABB TrafoStar Load Losses and Thermal Performance TM

Load Losses - Both the total load losses according to the Contract, and the detailed loss distribution are thoroughly calculated - The figure shows an example of the three loss types in a winding a) DC-loss (grey) b) Axial eddy loss (blue) c) Radial eddy loss (red)

- Well-known loss distribution in windings

© ABB BU Transformers - 44 -

and structural parts in active part and tank dangerous hot-spots are avoided improved serviceability of the transformer

ABB TrafoStarTM Load Losses and Thermal Performance

Minimize the risk of hot spots in tank and constructional parts

© ABB BU Transformers - 45 -

training of electrical engineers 3D Simulation user support network best practice guidelines simulation for different transformer designs

ABB TrafoStar - Short Circuit strength TM

Setting the criteria for permissible mechanical forces at fault currents Producing Mechanical Calculation Programs

© ABB BU Transformers - 46 -

Follow up on Short Circuit tests

ABB TrafoStar - Short Circuit strength TM

© ABB BU Transformers - 47 -

Mechanical model for spiraling in 3 D Simulation

ABB TrafoStar - Simulations TM

Power Transformer manufacturing is an ETO business: Design Elaborated simulation tools are essential and provide: Simulations

Simulation support & design rules Simulation Know-How Development of design tools

© ABB BU Transformers - 48 -

Design Tool Simulation Guide Result Design Rules

Training

ABB TrafoStar - Simulations TM

3D Design Verification

• Once the transformer is modelled in 3-D, the models are used for analysis and verification.

© ABB BU Transformers - 49 -

• Electrical stresses can be mapped and evaluated • Electrical clearances are checked. • Mechanical interferences can be verified. • Magnetic losses and temperatures in structural parts can be calculated

ABB TrafoStar - Simulations TM

Example of Design Tools: • For Engineering and Development work Transient Simulations (WINTRAN)

Insulation projects …

SpecTra 5.4

…

© ABB BU Transformers - 50 -

…

(Infolytica)

(ACE, Simulation toolbox)

Spiraling forces

Shielded Windings

Electro-thermal Simulations

Dielectric Simulations

Electro-mechanical Simulations Core design …

(Infolytica/Toolbox/ABACUS…)

ABB TrafoStar

© ABB BU Transformers - 51 -

Technical Standards

TM

Standard Documentation

ABB TrafoStar

© ABB BU Transformers - 52 -

Method Provisions

TM

Standard Documentation

ABB TrafoStar

TM

© ABB BU Transformers - 53 -

Material Specifications

Standard Documentation

ABB TrafoStar

TM

Standard Documentation

© ABB BU Transformers - 54 -

Sigma Cards & Instructions

ABB TrafoStar

TM

Standard Documentation

© ABB BU Transformers - 55 -

Test Standards - A set of common Test Standards is used by all plants to secure that the tests are made in the same way in all ABB test rooms

ABB TrafoStar Newsletters

TM

Standard Documentation

© ABB BU Transformers - 56 -

All new tools or methods are communicated via electronic Newsletters, distributed to Production and Operations Managers in particular plants. Copies of Newsletters are also located in commonly available LN database

ABB TrafoStar Uniform Tooling

TM

Standard Documentation

© ABB BU Transformers - 57 -

All standard tools and equipment are described in commonly available in Uniform Tooling database, including: specification, sourcing information and price of every tool. We constantly make sure our equipment is up to date and up to recent available technology.

© ABB BU Transformers - 58 -

ABB TrafoStar

TM

Standard Documentation

The follow-up of Metrics is an important tool to judge performance and to make benchmarking between transformer plants

TrafoStar – Design Process TM

Total Design Process Design Quality Assurance/ Design Review Basic Design Performance calculation Design verification Creation of design elements © ABB BU Transformers - 59 -

Integration of modules Verification using 3D CAD models Design for Short Circuit Strength Design for Transport Forces

TrafoStar – Total Design Process TM

Customer

Order clearing

Quotation

© ABB BU Transformers - 60 -

Forecast

Design review

Elec Design

Design approval

Mech Design

Material supply

Inspections

Manufacture

Witness

Test

TrafoStar – Design Quality Assurance / Design Review TM

Quotation review

Order clearing (Int and Cust) Pre-Design Peer Test Approval (Int and Cust) Pre-Design Peer Cross-check Approval (Int and Cust) Pre-start intro Logistics Inspections Audit

© ABB BU Transformers - 61 -

Test Report

Quotation

Elec Design

Mech Design

Manufacture

Test

TrafoStar – Basic Design TM

© ABB BU Transformers - 62 -

Basic Design parameters such as current density, flux density, winding turns, winding configuration and core dimensions are all optimized using the TrafoStar computer design tool Spectra, to achieve minimum Total Operating Cost

TrafoStar - Performance calculation TM

No Load Losses Load Losses Noise Levels

© ABB BU Transformers - 63 -

Temperatures

TrafoStar - Design verification TM

Transients Voltage distribution Stress calculation Magnetic flux Losses Temperatures Forces

© ABB BU Transformers - 64 -

AC Test Electrical stresses

TrafoStar - Creation of design elements TM

Computer calculated geometry. Automatic creation of manufacturing documentation for Windings, Core and Clamping structure. Automatic Winding Exit design

© ABB BU Transformers - 65 -

Templates for Tank, Conservator using pre-defined modules.

TrafoStar – Integration of modules TM

Proven design modules are maintained in a global library. These are re-configured or used directly.

© ABB BU Transformers - 66 -

#

TrafoStar - Verification using 3D CAD models TM

2D and 3D electric and magnetic field analysis

© ABB BU Transformers - 67 -

After a 3D model of the transformer has been created it can be used for analysis and verification. Electrical stresses can be mapped and evaluated Magnetic flux losses and hot spot temperatures can be calculated in structural parts Mechanical clearances can be verified.

Implementation Management in huge corporations Implement Design Technologies from global Design Development Team All instructions and revisions available on the corporate network. Notifications are sent out to keep everyone op to date. The IT design tools receive yearly releases Huge staff of design and IT engineers in global centersl ABB drives a Knowledge Communication Center in Germany where employees are educated and certified Secure and spread know-how Same engineering and production process

© ABB BU Transformers - 68 -

Improved contacts between factories

High Quality Power Transformers for Grid Reliability Agenda Market Background: The biggest Change since ever Loss Evaluations and impact on today's design Procurement processes ABB TrafoStar Technology and Design Consideration to build reliable transformers Manufacturing aspects © ABB BU Transformers - 69 -

Short Circuit Safe Design & Manufacturing&Testing Quality Management Summary remarks

TrafoStar Manufacturing Process TM

Winding

Winding Assembly

Core Cutting

Core Building

Cleats & Leads

Materials Receiving Internal Transport

© ABB BU Transformers - 70 -

Planning & Scheduling

Active Part Assembly

VP Drying

Tank Manufact.

Final Assembly

Test

Shipping

© ABB BU Transformers - 71 -

Core

© ABB BU Transformers - 72 -

Core

© ABB BU Transformers - 73 -

Winding

© ABB BU Transformers - 74 -

Assembly

© ABB BU Transformers - 75 -

Assembly

© ABB BU Transformers - 76 -

Test

© ABB BU Transformers - 77 -

Test

© ABB BU Transformers - 78 -

Shipping

Reliability of Power Transformers Testing of Power Transformers Dielectric Tests Seems OK today but “all” people talk about it

Thermal Tests Accuracy in Cold Resistance ? Are we measuring ambient correct ? Is Top Oil well defined ?

© ABB BU Transformers - 79 -

Heat Run stability ? Is winding temperature average enough?

Mechanical Tests This is the issue Today !! Are we making Short Circuit tests ?

High Quality Power Transformers for Grid Reliability Agenda Market Background: The biggest Change since ever Loss Evaluations and impact on today's design Procurement processes ABB TrafoStrar Technology and Design Consideration to build reliable transformers Manufacturing aspects © ABB BU Transformers - 80 -

Short Circuit Safe Design & Manufacturing&Testing Quality Management Summary remarks

Short - Circuit Withstand Capability Why talking about Fault Currents in network today ? Are Fault Currents affecting Transformers more today ?

© ABB BU Transformers - 81 -

Who cares about Mechanical Forces in transformers ?

Short - Circuit Withstand Capability History – Why SC tests ? SC tests have been used in different countries Reasons: Customers didn’t get SC safe transformers SC tests introduced 1950 -1960 SC tests have been debated during the years Many opinions in different countries about the needs and what one test shows © ABB BU Transformers - 82 -

IEC has edited new revised Standards SC tests seem very relevant to discuss today !?

Short - Circuit Withstand Capability Expanding cross-border electricity trade brings network operations close to their physical limits Development of wind generation integrates regions without taking into account available network capacities Load flows are changing Network components are ageing

© ABB BU Transformers - 83 -

The network operation conditions have changed New and old transformers will see more severe SC duty than before

Short - Circuit Withstand Capability Loss Evaluations are the same or lower since interest rates have been set higher after the privatization

© ABB BU Transformers - 84 -

Material prices (Copper, Core Steel, Oil, Electrical Board) have increased by a factor of 3 – 5

Qualitative discussion of materials utilization

"

!

© ABB BU Transformers - 85 -

!

Short - Circuit Withstand Capability How will all those changes affect today's transformer designs ? There are now more strong temptations to save active material and/or go closer to mechanical limits !!?? Are tenders from SC point of view comparable ?

© ABB BU Transformers - 86 -

Does the Industry have efficient measures/test Standards to check the mechanical integrity of such infrastructure products like Power Transformers ? New IEC SC standard proposes SC Tests or Design review evaluation/verification IEC proposes typical allowable, critical stresses

Short Circuit Integrity Electromagnetic forces tend to increase the volume of high flux or minimize the magnetic energy density in the volume • Inner winding towards

© ABB BU Transformers - 87 -

reduced radius • Radial Forces

• Outer winding towards increased radius • Radial Forces • Winding height reduction • Axial Forces

Short Circuit Integrity Radial forces failure modes: - Buckling of inner winding - Diameter increase of outer winding - Spiralling of end turns in helical winding

© ABB BU Transformers - 88 -

Axial forces failure modes: - Mechanical withstand of yoke insulation, core clamps and spacers - Conductor tilting - Axial bending between spacers - Telescoping

Short Circuit Integrity Buckling of inner windings

Unit removed after 15 years of service due to increased impedance. Note: No electrical damages

© ABB BU Transformers - 89 -

250 MVA, 400 kV auto

Short Circuit Integrity B

© ABB BU Transformers - 90 -

B

B

B

Fax

Fax

Fax

Fax

- Gaps in a winding will create large variations in the radial component of the leakage flux - Consequently, large axial forces will be developed

Short Circuit Integrity

© ABB BU Transformers - 91 -

Excessive axial forces towards yoke Damages from a SC test

Short Circuit Integrity Inner winding

Outer winding

Spiralling

© ABB BU Transformers - 92 -

A tangential shift of end turns in helical type windings

Short Circuit Integrity Spiralling on the winding of a 370 MVA GSU transformer during the short-circuit withstand test. a) entire outer layer of the LV winding

© ABB BU Transformers - 93 -

b) detail of the upper lead exit on the same layer heavily bent and distorted

TrafoStar Design for Short-Circuit Strength TM

Design with respect to radial forces: All windings are radially self supporting Inner windings are subject to “free buckling” No radial support A dynamic phenomenon

© ABB BU Transformers - 94 -

Strength is determined by Cu hardness (yield point) and conductor geometry

Outside windings are subject to tension Strength is determined by Cu hardness

TrafoStar Design for Short-Circuit Strength TM

Design with respect to axial forces: Axial forces are calculated by FEM Considering axial displacement due to workshop tolerance Considering axial displacement due to winding pitch when applicable Windings are dimensioned for maximum compression forces

© ABB BU Transformers - 95 -

Dynamic effects are considered by dynamic factors on the forces Winding ends are dimensioned for maximum unbalance forces and a part of the maximum compression force (“Bounce Back”)

TrafoStar Manufacturing aspects and accuracy TM

© ABB BU Transformers - 96 -

Strict Manufacturing Procedures and Tolerances

Short Circuit Strength Verification IEC gives two options to verify the ability to withstand the dynamic effects of a Short Circuit, IEC 60076 – 5: (2006-2)

© ABB BU Transformers - 97 -

By full SC test at a certified lab, or By theoretical evaluation of the ability to withstand a SC event by manufacturer’s experiences supported by IEC guidelines.

TrafoStar Short Circuit Strength – Verification by testing TM

300

•

35 TrafoStar short-circuit tested 1997 – 2008 Sept

250

© ABB BU Transformers - 98 -

•

7 with voltage 400 kV or above

•

10 rail track feeder transformers

•

3 test failures 32 / 35 = 91 % first pass rate

Rated Power MVA

200

150

100

50

0 1997

1998

2000

2001

2002

2005

2005

2007

2008

Short Circuit Tests at KEMA KEMA numbers published at CIGRE 2006 25 -30% of large transformers (> 25 MVA) fail to pass initially short-circuit tests.

16

20

initially not OK

16

initially OK

12 8 4 0 25-50

50-100

100-200

MVA (rated)

>200

n u m b e r o f tra n sfo rm e rs

© ABB BU Transformers - 99 -

n u m b e r o f tra n s fo rm e rs

No common root-cause

initially not OK

12

initially OK

8 4 0 20-100

100-200

200-300 kV (rated)

300-400

>400

Short - Circuit Withstand Capability From the statistics it seems that there are large differences in the number of SC test failures among manufacturers ABB has done the most number of tests during the years and have got a large amount of feedback and experience

© ABB BU Transformers - 100 -

ABB is using simple physical rules to calculate forces and applies modest critical stresses ABB has stringent manufacturing control on winding related dimensions and processes.

Short Circuit Recommendation All transformers are Dielectrically and Thermal tested Some very few are SC tested Customers shall consider in tender documentations to include new [email protected]:2006 Always to require manufacturers’ stresses compared with their allowed or critical values, deviations to IEC guidelines to be commented. Design reviews to be required

© ABB BU Transformers - 101 -

AND/OR

Mention in the specs that customer considers the rights to ask for SC tests one month after the order signature.

ABB Short Circuit Recommendation What units to be SC tested ? Important Generator Step Up transformers and Auxiliary units in Power Plants Key feeding transformers at Power plant Sub Stations or huge load centers Strategic Intertie Transformers 3 winding system transformers (Tertiary), Autos

Transformers with helical windings and axial split winding connections Series of transformers, one to be taken out © ABB BU Transformers - 102 -

Always Track feeding transformers Transformers connected to networks known for many faults and high fault currents

All Power Transformers designs/contracts to be checked by design reviews acc to IEC 76 Part 5 (2006-02)

TrafoStar Strategic Transformer Components TM

ABB uses it own manufactured Components On and Off Load Tap changers Bushings

© ABB BU Transformers - 103 -

Insulation material and Insulation Components

TrafoStar Electrical Components TM

Bushings

© ABB BU Transformers - 104 -

Off-Circuit Tap Changers

On-Load Tap Changers

TrafoStar Insulation TM

Outlets & Moulded Parts

© ABB BU Transformers - 105 -

Active part Insulation Kits

Winding Kits

TrafoStar – Kit Insulation Systems TM

Delivers ready for use on the winding mandrel improving… Productivity Space utilization Material flow Inventories

© ABB BU Transformers - 106 -

Capacity Quality

..and

© ABB BU Transformers - 107 -

Complete Active Part kits

Reliability of Power Transformers Agenda Market Background: The biggest Change since ever Loss Evaluations and impact on today's design Procurement processes ABB TrafoStar Technology and Design Consideration to build reliable transformers Manufacturing aspects © ABB BU Transformers - 108 -

Short Circuit Safe Design & Manufacturing Quality Management Summary remarks

TrafoStar Quality Management System TM

Quality Assurance in Sales, Project Management, Technology & Design, SCM, Production and Testing Continuous Improvement Process Quality Assurance in Packing, Transport & Site Assembly Training and Education Test Failure Management

© ABB BU Transformers - 109 -

Benchmarking

TrafoStar Quality Management System TM

Quality Assurance in all Business Processes

Project Management Front End

© ABB BU Transformers - 110 -

Technology & Design

Supply Chain Mgmt.

Production Testing

Packing & Installation & Transport Commissioning

TrafoStar Quality Assurance in Front End TM

Customer requirement review Design review process Concept/pre-design review

Process for Novelties Novelty Risk Assessment Process for introduction to manufacturing

Hand-over process © ABB BU Transformers - 111 -

Sales to Electrical Design Electrical to Mechanical Design and Test Mechanical Design to Supply Management and Manufacturing

TrafoStar Quality Assurance in Technology & Design TM

Designer Qualification Education Experience

Design Capacity Number of designers Access to expert support

Know-how development © ABB BU Transformers - 112 -

Formal and informal training Job rotation

TrafoStar Quality Assurance in Supply Chain Management TM

The level of vertical integration is very different for different manufacturers Supplier Qualification Process Supplier Quality Inspections Supplier Audits Supplier Performance Monitoring

© ABB BU Transformers - 113 -

Continuous Improvement Process

TrafoStar Quality Assurance in Supply Chain Management TM

© ABB BU Transformers - 114 -

Example: Radiators

Quality Inspection Cards

TrafoStar Quality Assurance in Supply Chain Management TM

2007 Auditors H. W. Kropp H. W. Kropp Troy Mullen/US H. W. Kropp

Number of Incoming Inspection Claim

Date

Audited 2005

Kari Miettinen/SE Audited 2005

April Sept March

Akk

B

C

D

E

F

G

H

I

Supplier Performance Statistics-Example

Number of Incoming Inspection Claim per Quarter

Supplier Error Statistics 2007 80

14.0% 12.0% 10.0% 8.0% 6.0% 4.0% 2.0% 0.0%

Q1

70

Q2

60

Q3 Q4 Akk

50 40 30 20

El ta Sc hw a. Th ys se n AS TA M its ui

A B C

D E

EM

M Sc R hm id t

lte c R& G

en k

10

Co i

M

Q4

A

Audited 2006 Richard Yngvesson/SE Leif Hakman/SE Leif Hakman/SE Rudolf Schutzeichel/DE

Supplier Audit Plan 2007

© ABB BU Transformers - 115 -

Q3

ui

Nov June

Q2

M its

Hakan Wikberg/DE Hakan Wikberg/DE Troy Mullen/US Hakan Wikberg/DE Hakan Wikberg/DE Bernt-Ove Hellström/SE

Q1

R& G

Audited 2005

Okt

AS TA

Hakan Wikberg/DE

40 35 30 25 20 15 10 5 0 M R

Commodity Slitting of electrical steel Electrical Steel Electrical Steel Electrical Steel Copper conductors Copper Foil Copper Foil Enamel copper wire CTC CTC & Enamelled copper wire CTC Copper conductors Copper conductors Aluminum Foil Accessories Accessories Thermometers Tap-changers Antwerp USA Radiator valves Radiators Radiators Radiators Sensors and Monitoring systems Porcelain Insulation paper Pre-compressed wood Epoxy resin mix

Sc hm id t Th ys se n Co i EM ltec Sc hw a.

Country Singapore UK USA Korea Spain Germany Germany Sweden Italy Korea Italy Malaysia Thailand Norway Italy Turkey Germany Germany Belgium Houston Germany India S. Korea Poland Canada Poland Sweden Germany Germany

El ta

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29

Supplier Kawasho Cogent AK Steel Posco Vicente Torns MKM KME Dahrentrad Invex Sam Dong De Angeli Metrod Metrod Hydro Aluminum Comem Elmek Messko MR Nynas Nynas Albert Maier GmbH TTP Sinjungwoo ZPREP GE SYPROTEC INC Zapel Munksjo Roechling Hexion (Bakelite)

M en k

AUDIT PROGRAM FOR GLOBAL & REGIONAL SUPPLIERS

F G H

I J

Supplier Performance Statistics-Example

0 -06 Average

Q1

Q2

Q3

Q4

-07 Average

Supplier Performance Statistics-Example

TrafoStar Manufacturing Process TM

Winding

Winding Assembly

Core Cutting

Core Building

Cleats & Leads

Materials Receiving

© ABB BU Transformers - 116 -

Internal Transport Planning & Scheduling

Active Part Assembly

VP Drying

Tank Manufact.

Final Assembly

Test

Shipping

TrafoStar Quality Assurance in Production TM

4

1 8

© ABB BU Transformers - 117 -

2

3

5

6

7

TrafoStar Quality Assurance in Production TM

1) Winding Process Control

IC1: Winding

© ABB BU Transformers - 118 -

IC2: Conductor Material

IC5: Brazing Control Sheet IC4: Preparation/Winding Assembly Inspection of coils prior to fitting outer wraps

IC3: Winding Insulation Material

Cp1

Skills Elec. Des, Mech.Des, QC, Manuf.

TrafoStar Quality Assurance in Production TM

Winding Process Control Windings •Shielding ring dimensions

© ABB BU Transformers - 119 -

6 sigma measurements in the manufacturing of windings! •Former cylinder •Inner oil ducts dimensions •Winding radial height •Winding height •Winding exit protrusion •Winding exit lead stability

Reduction of process variation

Control Point 1 in Inspection Card 4

© ABB BU Transformers - 120 -

Inspection and Test Plan controlling right performance of final tests

TrafoStar Continuous Improvement Process TM

Cost of poor Quality (COPQ) Every Power Transformer Factory is committed to integrate the COPQ process into its Continuous Improvement Process.

© ABB BU Transformers - 121 -

Sales

Proj.Mgt

Engg.

Supply

Manufact.

Transport

Installation Commissioning

Warranty

Support Processes

TrafoStar Training & Education TM

Training and Education is key in the approach for operational Excellence. Highly skilled and motivated employees are a precondition. Employees must be given continous education and training.

Operational Excellence Program (OEP) The OEP Program helps to develop Resources, increase competences and break down barriers.

© ABB BU Transformers - 122 -

Quality School Every Power Transformer Factory has a Quality School with an education program and a dedicated Classroom. The contents of the Training should be adapted to the maturity and existing knowledge and specific needs. Objectives of the Quality School are: Reinforce training and education in all key areas Secure good knowledge management and secure technical competence Estabish a formalized communication channel to all employees

Knowledge Communication Center (KCC) The KCC is a channel between the factories for Benchmarking and the exchange of Best Practices The KCC increases the competence throughout the corporation and within the Factories, encourages Teamwork and motivates employees. Knowledge Communication Center - KCC

TrafoStar Test Failure Management TM

The worldwide analysis of test failure is very critical !! The data provides the opportunity to learn, analyze and prevent recurrence. This helps us to continuously reduce our test failures and to reduce costs associated with poor quality. It also helps us to identify gaps in our guidelines, method provisions or work instructions.

© ABB BU Transformers - 123 -

Rules for Reporting and Management of Test Failures are described in an instruction. At least 3 times per year, a team of experts analysis all Test Failures on a global base and defines corrective actions.

TrafoStar Benchmarking TM

Having global manufacturing footprint with 14 factories worldwide. Benchmarking and best practice implementation is driver for continuous improvement

Process OK or improvement completed On-going improvements

© ABB BU Transformers - 124 -

Gap to be closed

Common Improvement

TrafoStar Platform – Global Feedback System TM

Measured Core Losses Measured Load Losses Measured Sound levels Measured Temperatures Measured Impedances Measured Pd Short Circuit Tests

© ABB BU Transformers - 125 -

Test Failures

All those performance data goes back to the Product Platform for maintenance, improvements and further developments !! An organization of 50 global engineers in 5 plants and CRC labs

Field Failures Non conformances reports of key processes A number of Key Performance Factors for key processes in an advanced global Operational Excellence structure

Reliability of Power Transformers Agenda Market Background: The biggest Change since ever Loss Evaluations and impact on today's design Procurement processes ABB TrafoStar Technology and Design Consideration to build reliable transformers Manufacturing aspects © ABB BU Transformers - 126 -

Short Circuit Safe Design & Manufacturing Quality Management Summary remarks

Risk mitigation in the Power transformer procurement chain

Recommendation for Customers 1. Most important specification parameters Specification must be well structured and clearly written Specify all requested functions rather than solutions Avoid hidden requirements easily overlooked by engineers on the manufacturer’s side Eliminate all requirements which complicate the transformer Specify the dielectric test levels with sufficient margin © ABB BU Transformers - 127 -

Short Circuit Tests ?, prolonged Heat Run Tests ? Do not exclude design solutions because this may force a manufacturer out of his standards

Risk mitigation in the Power transformer procurement chain

Recommendation for Customers & Suppliers 2. Basic important issues in a Design Review Check the design of the transformer for compliance with the service requirements Identify novelties and deviations from proven solutions Ensure that all vital functions are verified by testing

© ABB BU Transformers - 128 -

Verify that all important stresses vital for the long term service reliability have been calculated and are within proven and experienced limits by the manufacturer. Verify that the design is a result out from a well documented engineering system and accurate, consistent engineering TM tools/systems (ABB TrafoStar )

Risk mitigation in the Power transformer procurement chain

Recommendation for Suppliers 3. Material and Component Suppliers Ensure high quality material suppliers by Supplier Qualification Clear Material and Component Specifications ref to IEC and ANSI Standards

© ABB BU Transformers - 129 -

Continuous Improvements

Risk mitigation in the Power transformer procurement chain

Recommendation for Suppliers 4. Consistent Delivery Process and Quality System Well defined total process flow All manufacturing processes, equipments, tools are documented in Method Instructions Quality assurance in Technology & Design Supply Chain Management (SCM)

© ABB BU Transformers - 130 -

Production Testing Packing & Transport Installation & Commissioning

Continuous Improvement Process guided by a structured feedback system from test measurements, field experience

ABB TrafoStar Technology TM

A global Business Concept…… Basic Product Design Rules, Transformer Physics Product order design process & IT tools, Design Modules, Global Release system Methods and tools for product manufacturing

© ABB BU Transformers - 131 -

Method Provisions/Instructions and Common Tooling

Material/Component specifications Planning, Capacity reservation Supply Chain Management, contracts/audits, delivery times Quality Management Testing Training, global HR interactions, Knowledge Communication Center Global Feedback System

For long term reliability

ABB TrafoStar Technology TM

….for long term Reliability

© ABB BU Transformers - 132 -

Thank you for your attention !!

© ABB BU Transformers - 133 -