Design Improvement by Diagnostics of Transformers Still in Operation and of Apparatus Taken Out of...
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1 Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause: “Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service” 1 A Member of the Group Design Design Improvement by Diagnostics Improvement by Diagnostics of of Transformers Transformers still in Operation still in Operation and of and of Apparatuses taken Apparatuses taken out of Service out of Service Christoph Krause Christoph Krause Weidmann Weidmann Transformerboard Transformerboard Systems, Systems, Switzerland Switzerland Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006 "New Diagnostic Concepts for Better Asset Management"
description
Improvement of transformer designs through diagnosis of transformer in service and transformers out of service
Transcript of Design Improvement by Diagnostics of Transformers Still in Operation and of Apparatus Taken Out of...
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
1A Member of the Group
DesignDesign Improvement by DiagnosticsImprovement by Diagnostics ofofTransformersTransformers still in Operationstill in Operationand ofand of Apparatuses takenApparatuses taken out of Serviceout of Service
Christoph KrauseChristoph Krause
Weidmann Weidmann TransformerboardTransformerboardSystems, Systems, SwitzerlandSwitzerland
Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006"New Diagnostic Concepts for Better Asset Management"
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Contents1. Power rating enhancement by elimination of the limitation set by induced tank
heating through a complex, three-dimensional electromagnetic-thermal study of a transformer still in operation, and subsequent design adaptation.
2. In-depth diagnostics of aged transformers by forensic investigations after having been taken out of service before being scrapped
provides accurate information about the cooling efficiency of the apparatus.
enables better assessment of the status of similar transformers in the grid
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Contents1. Power rating enhancement by elimination of the limitation set by induced tank
heating through a complex, three-dimensional electromagnetic-thermal study of a transformer still in operation, and subsequent design adaptation.
2. In-depth diagnostics of aged transformers by forensic investigations after having been taken out of service before being scrapped
provides accurate information about the cooling efficiency of the apparatus.
enables better assessment of the status of similar transformers in the grid
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
3D case study: Electromagnetic re-design to prevent tank overheating
185 MVA 1ph GSU Transformer
Target:Upgrade MVA-performance by > 20% of name plate rating
Problem:Tank flange hot spot = 96°C at 190 MVAThe enhanced oil cooling could not cope with the local tank hot spot
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Thermal scan at 190 MVA
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Inspection on site
Shorting plate disassembled
185 MVA 1ph GSU Transformer
Bushing
No MagSteel Cover
¾”
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Flux Tangential Boundary Condition
Plane of symmetry
Technical challenges:• Aluminum shields inside the tank• Mild steel tank wall• Non-magnetic steel cover parts• 3-dimensional modeling
Modeling the zone of interest
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Creating the FEM mesh: 269‘000 (number of tetraedra)
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
3-D calculation of losses
Infrared scan
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Original Design
Improved Design
Acting together with the manufacturer of the current bus enclosures, a different
design was developed with significantly lower losses in the critical area of the tank
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Creating the FEM mesh
Detail view
659‘000 (number of tetraedra)
The mesh was generated using only standard mesh controls, i.e. no special methods were needed.
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Original ModelModified Model
Design
Improvements
Losses in the zone of interest
scale: from 0 to 2.5x105 W/m3
Loss distribution
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
3D case study: Electromagnetic re-design to prevent tank overheating
•
at 190 MVA, tank flange hot spot = 96°C
at 228 MVA, tank flange hot spot = 72°C Re-Design
Original Design
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
3D case study: Electromagnetic re-design to prevent tank overheating
Summary:Localized tank cover flange heating detected by infrared scanDiagnosis technical challenge: aluminum shields inside the tank,mild steel tank wall, non-magnetic steel cover parts – 3D modeling The simulation provided excellent match with the measured tank temperaturesThe solution consisted in moving the crossover shorting plate to shift flux induced currents from the tank cover flange to themiddle of the tank coverRedesigned busbar enclosure permits transformer upgrade from 185 MVA to 228 MVA.
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Other types of simulations / calculations being performed• Losses (with/without harmonic currents) and impedance of:
• Windings (including foil windings and complex circuit arrangements)• 3D bus bars arrangements• Reactors (with/without core, with/without magnetic shielding)
• Current distribution in high current windings as occur in industrial applications (arc furnace AC & DC, rectifiers)
• (3D): Losses in tanks, electromagnetic shields and conductive structures• Temperature distribution on tanks (3D)• Short circuit: computation of (transient) currents and peak forces on windings• Switch-on: computation of transient currents forces on primary winding• Electric field studies
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Today, we are performing magneto-thermal calculations regularly – local overheating is a problem that occurs frequently.Here another example of such calculation of a GSU transformer. The results are shown on left hand side and the thermal scan is shown on right hand side.
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Reference listABB Cordoba, Spain ABB Industrial Transformer Legnano, Italy and Bad Honnef, Germany ABB Rectifiers, Turgi, SwitzerlandABB Research Center, Baden, SwitzerlandABB Varennes, CanadaAREVA T&D, Stafford, UKAREVA, Dubai, U.A. EmiratesASA Trafobau GmbH, Bad Arolsen, GermanyCrompton Greaves Ltd, Mumbai, IndiaDUBAL, Dubai, U.A. Emirates Dynegy, Houston, TX, USAFRIEM Rectifiers, Segrate, ItalyFrance Transfo, Metz, FranceMatelec Group, LebanonPioneer Transformers Ltd, CanadaPII GE, UKPortland GE Company, Oregon, USASTEM Transformers, Trento, ItalyTamini Group, Melegnano, ItalyTranspower, New ZealandWilson Transformer Company, Victoria, Australia
(some of our customers)
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Contents1. Power rating enhancement by elimination of the limitation set by induced tank
heating through a complex, three-dimensional electromagnetic-thermal study of a transformer still in operation, and subsequent design adaptation.
2. In-depth diagnostics of aged transformers by forensic investigations after having been taken out of service before being scrapped
provides accurate information about the cooling efficiency of the apparatus.
enables better assessment of the status of similar transformers in the grid
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Motivation for in-depth diagnostics of aged transformers by forensic investigations:
Compare real aging with laboratory accelerated aging experiments(DP, water and acid content, tensile and bending strength, dissipation factor tan δ, resistivity)
Verify the cooling performance of the transformer active part
Assess the initial DP values of different solid insulation components (when the transformer was put in service)
Identify the location of the true hot spot(s)
Detect unintended, hot spot areas / design flaws
Appraise of the aging condition of similar transformers still in operation
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Equipment and toolsWork clothesWork safety
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Equipment and toolsKnivesScissors for cutting paper samples
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Equipment and toolsCuttingSawing
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Equipment and toolsPincers of any kind
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Equipment and toolsPlastic bags Paper tagsPens (oil and water resistant)
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Equipment and toolsOil container Plastic foilBoxes and crates
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Determination of the aging status by measuring the DP (Degree of Polymerization) of cellulose samples
In operation, the cellulose degrades continuously with timeThis degradation alters (shortens) the cellulose moleculesThe DP is a good measure of the aging status, because it is proportional to the average length of the cellulose moleculesThe DP of new Kraft pressboard and -paper is about 1200, that of completely aged (end of life) about 200.
time (years)
DP (t)500
1000
DP
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Transformer AVoltage: 110 / 63 kVRating: 31.5 MVAPhases: 3Cooling: ONAFManufacturer: Siemens Schuckert, Berlin, GermanyOperating utility: E.ON, GermanyIn service: 1955 - 2003
Transformer BVoltage: 220 / 110 kVRating: 140 MVAPhases: 3Cooling: OFAFManufacturer: TRO, Berlin, GermanyOperating utility: Vattenfall, GermanyIn service: 1974 - 2004
Transformer CVoltage: 380 / 220 kVRating: 600 MVA / 3Phases: 1Cooling: OFAFManufacturer: MFO, Zurich, SwitzerlandOperating utility: NOK, SwitzerlandIn service: 1962 - 2005
Measurements of the aging status of cellulosic insulation samples taken from three power transformers
region of sample taking (top to bottom along axial height)
one phase
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Transformer AVoltage: 110 / 63 kVRating: 31.5 MVAPhases: 3Cooling: ONAFManufacturer: Siemens Schuckert, Berlin,
GermanyOperating utility: E.ON, GermanyIn service: 1955 - 2003
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
401-500
601-700701-800801-900
Windings
< 200201-300301-400
LV HV Tap
501-600
> 900
Cor
e
0
200
400
600
800
1000
1200
Deg
ree
of P
olym
eriz
atio
n
bottommiddletop
LV HV Tap
Transformer AVoltage: 110 / 63 kVRating: 31.5 MVAPhases: 3Cooling: ONAFManufacturer: Siemens Schuckert, Berlin,
GermanyOperating utility: E.ON, GermanyIn service: 1955 - 2003
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Transformer BVoltage: 220 / 110 kVRating: 140 MVAPhases: 3Cooling: OFAFManufacturer: TRO, Berlin, GermanyOperating utility: Vattenfall, GermanyIn service: 1974 - 2004
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Cor
e
DPTert LV HV Tap
Windings
> 900
501-600601-700701-800801-900
< 200201-300301-400
401-500
0
200
400
600
800
1000
1200
Deg
ree
of P
olym
eriz
atio
n
bottommiddletop
LV HV Tap
Transformer BVoltage: 220 / 110 kVRating: 140 MVAPhases: 3Cooling: OFAFManufacturer: TRO, Berlin, GermanyOperating utility: Vattenfall, GermanyIn service: 1974 - 2004
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Transformer CVoltage: 380 / 220 kVRating: 600 MVA / 3Phases: 1Cooling: OFAFManufacturer: MFO, Zurich, SwitzerlandOperating utility: NOK, SwitzerlandIn service: 1962 - 2005
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
0
200
400
600
800
1000
1200
Deg
ree
of P
olym
eriz
atio
n
bottommiddletop
LV HVTertiary
> 900801-900
Windings
701-800601-700501-600401-500301-400201-300< 200
DP
Tertiary LV HV
Cor
e
laminated strips
cylindersTransformer CVoltage: 380 / 220 kVRating: 600 MVA / 3Phases: 1Cooling: OFAFManufacturer: MFO, Zurich, SwitzerlandOperating utility: NOK, SwitzerlandIn service: 1962 - 2005
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
02468
10121416
0 250 500 750 1000Degree of Polymerization
Freq
uenc
y B C
A
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
0
200
400
600
800
1000
1200
0 10 20 30 40 50
Aging time (years)
Deg
ree
of p
olym
eriz
atio
n
90°C
80°C
70°C60°C
100°C110°C
0
200
400
600
800
1000
1200
0 10 20 30 40 50
Aging time (years)
Deg
ree
of P
olym
eriz
atio
n
90°C 80°C70°C
60°C
50°C
40°C
Influence of water on the ageing rate
teADP
1)t(DP
1 TRE
0
A
⋅⋅=− ⋅−
Aging kinetic equation:Due to the moisture increase during transformer life, the determination of the operational temperature, at different locations in the transformer, is not precise.
2% water content <0.5% water content
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
SummaryThe DP profiles matched the expectation: lower DP-values at the winding top and around the conductors, higher values at the bottom and of the inter-winding insulation.
The insulation of transformers A (50 years) and C (40 years) was still in relatively good condition.
The youngest transformer B (30 years) had reached its end of life - continuing operation would have been associated with catastrophic failure hazard.
• The moisture content was high, perhaps right from the beginning?• The DP of paper at the beginning of life time was lower, due to overheating
during drying? • The cooling design was insufficient?• The transformer was operated beyond name plate?
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
RemarksIt takes relatively little effort to collect solid insulation samples, when power transformers are scrapped. The findings may be of high value.
For a comprehensive aging replica, it is necessary to take samples systematically throughout the transformer.
With the water content information of the samples, it is possible to assess the operating insulation temperatures with better precision. Yet, measuring the moisture of the samples requires quick handling on-site, due to inevitable water absorption when exposed to the (humid) air.
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Preconditions for valuable forensic analysis of power transformersAcceptance of project and orientation of the transformer scrapping staff, surplus time is about 1 dayTransformer drawings for determination of sampling; transformer design & calculation documents
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Preconditions for valuable forensic analysis of power transformersAcceptance of project and orientation of the transformer scrapping staff, surplus time is about 1 dayTransformer drawings for determination of sampling; transformer design & calculation documentsPlan (sequence of dismantling): winding, top to bottom, radial orientation, inter-winding insulation, different phases
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Preconditions for valuable forensic analysis of power transformersAcceptance of project and orientation of the transformer scrapping staff, surplus time is about 1 dayTransformer drawings for determination of sampling; transformer design & calculation documentsPlan (sequence of dismantling): winding, top to bottom, radial orientation, inter-winding insulation, different phasesAssigned responsibilities on site: who is doing what Experts shall take the samples
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Preconditions for valuable forensic analysis of power transformersAcceptance of project and orientation of the transformer scrapping staff, surplus time is about 1 dayTransformer drawings for determination of sampling; transformer design & calculation documentsPlan (sequence of dismantling): winding, top to bottom, radial orientation, inter-winding insulation, different phasesAssigned responsibilities on site: who is doing what Experts shall take the samples(local) Work safety instruction and strict adherence to
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Preconditions for valuable forensic analysis of power transformersAcceptance of project and orientation of the transformer scrapping staff, surplus time is about 1 dayTransformer drawings for determination of sampling; transformer design & calculation documentsPlan (sequence of dismantling): winding, top to bottom, radial orientation, inter-winding insulation, different phasesAssigned responsibilities on site: who is doing what Experts shall take the samples(local) Work safety instruction and strict adherence toTime (patience). Envision unforeseen difficulties and effects. Teamwork!
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Preconditions for valuable forensic analysis of power transformersAcceptance of project and orientation of the transformer scrapping staff, surplus time is about 1 dayTransformer drawings for determination of sampling; transformer design & calculation documentsPlan (sequence of dismantling): winding, top to bottom, radial orientation, inter-winding insulation, different phasesAssigned responsibilities on site: who is doing what Experts shall take the samples(local) Work safety instruction and strict adherence toTime (patience). Envision unforeseen difficulties and effects. Teamwork!Transformer operation records: temperatures, oil moisture, maintenance (oil reclaiming etc.), power flowCo-operate with transformer manufacturer - difficulty: old apparatusesRespect (local) working hours (unions!)
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
Preconditions for valuable forensic analysis of power transformersAcceptance of project and orientation of the transformer scrapping staff, surplus time is about 1 dayTransformer drawings for determination of sampling; transformer design & calculation documentsPlan (sequence of dismantling): winding, top to bottom, radial orientation, inter-winding insulation, different phasesAssigned responsibilities on site: who is doing what Experts shall take the samples(local) Work safety instruction and strict adherence toTime (patience). Envision unforeseen difficulties and effects. Teamwork!Transformer operation records: temperatures, oil moisture, maintenance (oil reclaiming etc.), power flowCo-operate with transformer manufacturer - difficulty: old apparatusesRespect (local) working hours (unions!)
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
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Weidmann-ACTI Inc. Fifth Annual Technical Conference, Albuquerque, 13-15 Nov 2006; Christoph Krause:“Design improvement by diagnostics of transformers still in operation and of apparatuses taken out of service”
