# Computer Aided Design of Transformer Latest

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```					    Computer Aided Design of
Transformer
- By

L . Ravi Patnaik

1                       Vijai Electricals Ltd
Introduction

   Design has been defined as both an art & a science . It is an art
because of the uncertain factors & decisions involving judgement or
experience and science because these decisions cannot be
arbitrary.

   An engineering design problem is usually stated as : Devise ,
subject to certain problem solving constraints , a system or a
process to accomplish a specified task optimally , under certain
solution constraints.

   There are two type of constraints :
1) Problem Solving procedure
2) Cost & availability of materials , equipment & manufacturing
skills.
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Methods
 Two types of methods used in designing
    Analysis:
The determination of the performance of a system
from knowledge of relationships among the variables ,
with the system parameters defined initially remained
unchanged . In most cases , the calculated performance
may not agree with the specifications & may modify the
initial estimate parameters.

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Synthesis:
The performance characteristics are substituted in
the mathematical model to solve for the physical properties
of the desired system . Numerical techniques have to restore
& process iterations may be used.

For these methods & constraints we have to deal with
MATHEMATICAL PROGRAMMING .

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 In practical design , the number of variables involved is so
high the the hand calculation are impossible . The number of
constraints is also large & for these to be satisfied By the final
design , a lengthy iterative approach is required . For that fast
computer using mathematical programming technique is
feasible. That’s we call “COMPUTER AIDED DESIGN”

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Need in transformer

Transformer are Electrical & mechanically CUSTOM
DESIGEN PRODUCTS.

These are built by the following main assemblies with different
constructional features

   Core & coil assembly
   tank
   mineral oil(optional)
   External fittings & accessories

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Every order needs:-

Different design & a very in depth , step-by-step calculations at
design stage of transformer , from raw materials to finished
product.

Set of customer & mfg drawings

 Bill of materials

“ COMPLETE ENGINEERING INFORMATION”

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Why different types Engineering
information required

Just move around the TRANSFORMER

Application Phase
single
three
Core construction
stacked core
wound core
In single phase
Core type
Shell type
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In three phase
core type
shell type
Winding coil
Round coil
Rectangular coil
 Conductor material
Aluminium
Copper
Conductor cross section
Round
Rectangular
Tank
Rectangular
Round
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Shape of tank
   Rectangular type or      Round type or single
three phase               phase

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Cooling Fitting arrangement
Cooling arrangement
Round cooling tubes
Corrugation fin panel
Elliptical cooling tubes
Different features in External fitting
Bushing
Valves
PRD
Measuring gauges
& many more

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Electrical calculation
Core area & steps.
Volt per turn.
Lv turn & Hv turn.
Coil axial heights & radial depths.

Impedance
& many more to list…..

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Mechanical calculation
Core frame size
Insulation details
Heat dissipation details
Cooling providing Arrangements
Fixing of tank Sizes
External fittings Positions
& many more………..

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Chance to commit mistakes &
errors:

Production time
Materials
Money
& lots of loss

For this “SOME NEED , BEST PRACTICES…….”

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Objective & Constraint functions:
 For an economical design of a transformer , the objective or cost
function should consist of :
F = Initial cost + capitalized cost of losses + cost of external heat
exchangers( if required)
 Degree of utilization of a transformer is limited by certain
constraints:
1) Temperature rise of windings & top oil above ambient
2) %age short-circuit impedance
3) Magnetic flux in core
4) Current density in windings
5) %age efficiency at full load

16                                                         Vijai Electricals Ltd
Computer design system
This design automation program curricumlum incorporates theory ,
applications & practical experience from the manufacturing with
current technical knowledge , skills & practice & ideas.

Visual Basic
Oracle

17                                                    Vijai Electricals Ltd
How does transformer design
software work?
 Enter the customer details:
 Just enter the KVA rating , H.V./L.V. , connections( delta/star) ,
taps ( in terms of % ) , temp rise of oil & winding & materials
used.This part is used in front end (Visual basic).

 It will calculate core diameter based on constants of the material
, flux density & number of steps used in core assembly .

 If it doesn't match the near value of max flux density again it will
do the calculation till it get the near desired value . So this
requires number of iterations which can be done fast by
computer .

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Once the core diameter is found LV/HV diameter can be found by
number of turns with tap , conductor diameter & using the radial
depth of the winding . Also axial height can be found .

Weight can be calculated by volume & density of conductor &
insulations . By this no load loss calculated .
 Resistance,load losses , % reactance are calculated .

All this are done by “BACK END” language i.e. Oracle for the
calculations & data base . To select the optimal design of cca it has
to do number of iteration & calculations .

To visualize the cca we use “AUTOCAD” .
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After getting the cca dimensions , tank calculation is done with the
loss watts to be dissipated by providing the sufficient cooling
arrangement apart form the tank body.

This final design of complete transformer is done by visual impact
with the accurate dimensions in 3D in “AUTOCAD-VISUAL LIPS”.
To get the better optimal design & user friendly we can update :
                   Dot net
                   oracle
                   Pro e

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Parametric driven system
Independent parameters
They are derived from the specification , rating , customer
requirements & KVA of transformer
    Vector relation ships
    primary & secondary voltage
    Frequency
    Tap changers’
    Current densities
    Ref temperature
    Oil rise , winding rise
    BIL & many more………
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Avoids error
Faster & easy decision making
Time saving
Maintains the standardization
product_img_1_b.jpg
Maintains complete engineering information
Leverage the engineering productivity
Simple & easy to use

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