Dr. Shamasundar spoke about the thermal management in transformers, different cooling methods and how simulation through JMAG can help you design an Efficient Transformer.

1. Transformer Technology Symposium 2016
Dr S Shamasundar
ProSIM R&D Pvt Ltd
Thermal Management of Transformers
Thermal & Flow Analysis

2. Transformer Technology Symposium 2016
Design
Tool
Design
Verification,
Analysis and
Optimisation
Virtual
Prototyping and
Testing
Inputs
Inputs
OK
NO
Design
OK
Release
control
mfg
drawings
A framework of integrated software for Transformer
Design and Optimisation
Physical
Prototype
Physical Test and
Type Approval
OK
Fine
Tune??
NO

3. Transformer Technology Symposium 2016
Inputs
Design
Requirements /
Specifications
Material
DESIGN
TOOL
Formulae
Transformer
design
calculations
Assumptions
Output
Geometry
Mass Ratios,
BOM, design
details
A customised design tool can be developed. ProSIM has network who can such
design automation tools for Power and transmission transformer design.

4. Transformer Technology Symposium 2016
Design Verification
and Optimisation tool
Inputs
- All design details
- Geometry of core,
tank, cooling circuit,
joinery, etc
- Input / output current
/ voltage
- Material of core, and
mechanical structures
- Connection details
Outputs
Stray Loss
Short circuit forces
Impulse distribution
Tank stresses
No Load losses
Load Losses
Impedance
Temperature rise
Mode shapes /
Vibration
Stresses / pressure
JMAG software will take the design inputs
and analyse the entire transformer.
JMAG is also used as a virtual prototyping
and virtual testing tool.

5. Transformer Technology Symposium 2016
Design
Calculations
• Geometry
• Winding details
• Materials
• Circuit details
• Performance estimate
EMAG
• Losses
• Magnetic Flux
• Current Density
• Temp Rise due to loss
Thermal
• Conduction
• Convection
• Steady State
• Transient Thermal
Mechanical
• Vibration
• Noise
• Stress, Pressure
Other
Studies
• Transportation
• Seismic
• Failure Analysis
• Life Assessment
Abaqus

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Thermal Management
• Standard rating and overload capacity
• Temperature Rise and efficiency
• Transformer Life
• Overload Capacity
• Confined spaces
• Designing Transformers for Low Temperature Rise

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Efficient Transformers
=
Lower Temp Rise
Source of Heat

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Transformer Thermal Management
Mitigation of Losses – Enhancement of Cooling

9. Transformer Technology Symposium 2016
Types of cooling techniques
Air Natural / Self Air Cooled Transformer Shell type.
Oil Natural Air Natural.
Oil Natural Air Forced.
Oil Forced Water Forced.
Note: Images are taken from Open source

10. Transformer Technology Symposium 2016
• Used in small transformers (up to
3 MVA).
• Transformer cooling by natural air
convection
• No external cooling is used.
Air Natural Cooling
Note: Images are taken from Open source

11. Transformer Technology Symposium 2016
• Oil immersed transformers.
• Heat generated in the core and
winding is transferred to the oil.
• Used for transformers up to about
30MVA.
Oil Natural Air Natural.
References: http://www.google.com/ electricaleasy.com

12. Transformer Technology Symposium 2016
• The heat dissipation can be improved
further by applying forced air on the
dissipating surface.
• This transformer cooling method is
generally used for large transformers
up to about 60 MVA.
Oil Natural Air Forced
References: http://www.google.com/ electricaleasy.com

13. Transformer Technology Symposium 2016
• Oil is circulated by a pump.
• The oil circulation is forced through the heat
exchangers.
• This type of cooling is provided for higher
Oil Forced Water Forced

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.

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What Codes Say
• Standards / Codes such as IEC 354 (loading guide for oil immersed transformers)
• IEEE C57.91
• IEEE 1538 guide for determination of maximum temperature rise in liquid filled transformers etc…

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Relationship Between Physical Phenomena and Analysis Models

21. Transformer Technology Symposium 2016
Hot spot Temperature identification
Temperature distribution in tank
Temperature distribution in core
Temperature distribution in Core

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Velocity and
temperature
distribution
in disc
windings

24. Transformer Technology Symposium 2016
Case study 2: Hot Spot Temperature Analysis in Transformers
Objective: To investigate Solenoid-type windings
transformer from simulation of a 3 phases 10 MVA
transformer.
Design parameters of the transformer
The primary and secondary windings have 16 layers
and each layer 45 turns. The main parameters of the
transformer are:
Rating:10MVA, Voltage: 63/20 kV, Current: 90/290A,
Frequency: 50 Hz, Phase: three-phase
Magnetic field distribution in typical transformer
Thermal field distribution in typical transformer
References: “Hot Spot Temperature Analysis in 3 Phase Transformers Using FEM Method”, ISSN: 2249-6645, Vol.1, Issue.2, pp-425-429, Published
at International Journal of Modern Engineering Research (IJMER)

25. Transformer Technology Symposium 2016
Case study 3: Distribution Transformer Cooling System
Improvement
Objective: To evaluate the proper cooling for
the existed design of electrical transformer
(160KVA).
Electrical transformer active part and typical transformer oil tank
The transformer active part thermal distribution
Active part contours used for the visualization of the
temperature distribution results
References: “Distribution Transformer Cooling System Improvement by Innovative Tank Panel Geometries”, Vol. 19, No. 3, Published by IEEE
Transactions on Dielectrics and Electrical Insulation in June 2012

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Case study 5: Temperature distribution in geometry
Velocity distribution of oil in the transformer by FEA
Objective : To study the velocity distribution
of oil flowing inside the transformer.
The FE analysis is carried out by considering
the partial section of electrical transformer
and analyze the velocity distribution at each
point in that section. This velocity
distribution will help to know the
temperature carrying capability of that oil at
each point.
References: http://www.google.com/ electricaleasy.com

27. Transformer Technology Symposium 2016
Dr S Shamasundar
ProSIM R&D Pvt Ltd
Vibration & Stress Analysis of
Transformers

28. Transformer Technology Symposium 2016
Sources of Vibration
• Winding Vibrations
• Core Vibrations
– Forces for excitation are
• Magnetostriction
• Electro-magnetic force
• Lorentz force

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Possible domain structures, showing large magnetostatic energy associated
with isolated domain (a), and successively lower energies associated
with (b), (c) and (d). The last represents the kind of domain structure
actually observed. In (c) and (d) the 90 degrees Bloch Walls are clearly visible at
the top and bottom.
Magneto-Acoustic Emission (MAE)

31. Transformer Technology Symposium 2016
THANK YOU