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Computer Aided Design of Transformer Latest

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					    Computer Aided Design of
                Transformer
                                 - By

                L . Ravi Patnaik


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    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
  Radiators
  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.
Load losses & no load losses.product_img_1_b.jpg



Winding gradients.
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:
Which leads to loss of

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
6) %age no load current

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 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
                            AutoCAD-Visual lisp




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 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
     winding gradients
     Ref temperature
     Oil rise , winding rise
     BIL & many more………
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 Advantages
      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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posted:6/2/2012
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