Download - Optimalization Design Rules
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Technical Documentation
2009
Peter Arras---------------------------------------------------------------------
Optimization of design rules
for power transformers
through FEA
Ing. Peter Arras
De Nayer, Belgium
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International conference on
New trends in design and
Technical Documentation
2009
Peter Arras---------------------------------------------------------------------
Introduction
Transformer design 2D
Optimalisation of the design process
Evaluation of existing design rules
FEA analaysis and conclusions
750MVA transformer
Conclusions.
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International conference on
New trends in design and
Technical Documentation
2009
Peter Arras---------------------------------------------------------------------
Power transformers: tailor made.
Pauwels Trafo: 60 years of tradition in transformers
2000 employees Represented in 135 countries
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Technical Documentation
2009
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Design of housing: 2D CAD
Example of 375 MVA transformer.Overall dimensions of housing:
approximatif 5x2.5x3 mm
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New trends in design and
Technical Documentation
2009
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Design through 2D CAD:
Design based on experience
Design rules lead to a library of components
which is not changed.
Design rules are static: no changes because theimpact on the CAD-design would be to great.
Errors common to 2D design:
Missing/different dimensionsin different views
Missing components: toosmall details onthe big overall
drawingwere left out for the sake of the drawing, but
forgottenfor the extractionof workingdrawings.
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Technical Documentation
2009
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Optimalisation of the design process.
Evaluate existing design rules
Calculate through FEA strengths of
housings: calculations demanded by
the customers. Restructure design to 3D CAD.
Minimize dimensional errors
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International conference on
New trends in design and
Technical Documentation
2009
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Scheme of approach:
Evaluation of existing design rules: Calculation of 1 existing design
Calculation of 5 new designs with existing
design rules
Conclusions
Calculation of new 750MVAtransformer
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Technical Documentation
2009
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Evaluation of existing design rules
FEA calculation scheme: Stripping of the 2D design drawing for 3D
modelling of the housing.
3D- Modelling of the housing
Construction of the FEA-model over the 3D CAD-
model
Constraining/loading
Calculation
Conclusions.
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International conference on
New trends in design and
Technical Documentation
2009
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Stripping of the 2D design drawing
2D CAD model contains all components forcalculation of prices
Contains no dimensioning scheme
No full projection relation between views
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International conference on
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Technical Documentation
2009
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Stripped model.
Simplification of: Welds (left out)
Profiles (no fillets)
Components: only housing
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International conference on
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Technical Documentation
2009
Peter Arras---------------------------------------------------------------------
3D model: detail of inside
Corner reinforcements
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Technical Documentation2009
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FEA calculations
Calculations done with Pro Engineer
MechWildfire 3.0.
Test as a design tool Quick
Evaluate design rules:
Plate thickness Distance between strengthenings
Shape of strengthenings
Evaluate possible 3D design Recuperation of 3D CAD effort?
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New trends in design and
Technical Documentation2009
Peter Arras---------------------------------------------------------------------
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International conference on
New trends in design and
Technical Documentation2009
Peter Arras---------------------------------------------------------------------
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FEA model
Analysis type: 3D shell model
Loadcases:
Vacuum load: zero pressure on inside, bottomof transformer constrained to ground
Lifting of transformer: weight of active part,
weight and hydrostatic pressure of oil fi ll ing,
own weight, constrained on 3 out 4 lifting
hooks.
Jacking of transformer: weight of active part,
weight and hydrostatic pressure of oil fi ll ing,own weight, constrained on 3 out 4 standing
feets/weel bases
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New trends in design and
Technical Documentation2009
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FEA model
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New trends in design and
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Conclusions
Design rules: Major design rules can be kept
Allowable material strength has to be reduced
from 240 MPa to 215 MPa
3D CAD solution: Complete 3D (detailed) design demands:
Training of personel Reworkof CAD-libraries
Only minor gain for FEA model: Needsa lot of stripping, feature removal
Solves: dimensional errors.
Missing components.
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Technical Documentation2009
Peter Arras---------------------------------------------------------------------
750 MVA transformer.
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Technical Documentation2009
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750 MVA transformer
Biggest transformer ever build at
Pauwels Trafo
Some facts: total weight 306.5 tons
active part: 131 tons
housing 10x4x4m high voltage isolators 1800 kg/each
Oil fill ing: 90000 l
Needs calculation of housing, coverand beams for active part
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750 MVA transformer: calculation of housing
Applied rules: Distances between strengthenings according to
old rules
Material allowable strength: 215 MPa
Inner reinforcement triangles substituted with
long plate
Calculation: Load: vacuum, lifting and jacking.
Special care taken on excentric loading due to
heavy weight of high voltage isolators and
fitting.
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Technical Documentation2009
Peter Arras---------------------------------------------------------------------
750 MVA transformer: 3D stripped model
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Technical Documentation2009
Peter Arras---------------------------------------------------------------------
750 MVA transformer: FEA model
6000 shell elements, 7 beams and 3
mass-elements
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Results after adding extra reinforcements
Vacuumload.
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Stress while jacking the housing.
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Conclusions.
After 3D modelling the housing: Dimensional mistakes in 2D CAD drawing corrected
After calculation: Extra strengthening needed around high voltage fittings
Excessive bending in r ight end wall.
On design rules: New rules result in fair design Decreased allowable stress together with simple
increasing of wall thickness leads to easy changes in the
design. In earlier cases design were worked over with
more profiles, repositioning etc, which were time- andmoney consuming.