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RICH DAD POOR DAD BOOK REVIEW

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  RICH  DAD  POOR  DAD  BOOK REVIEW This is amazing book.   • Explodes the myth that you need to earn a high income to become rich • Challenges the belief that your house is an asset • Shows parents why they can't rely on the school system to teach their kids about money • Defines once and for all an asset and a liability • Teaches you what to teach your kids about money for their future financial success It's been nearly 25 years since Robert Kiyosaki’s  Rich Dad Poor Dad  first made waves in the Personal Finance arena. It has since become the #1 Personal Finance book of all time... translated into dozens of languages and sold around the world. Rich Dad Poor Dad  is Robert's story of growing up with two dads — his real father and the father of his best friend, his rich dad — and the ways in which both men shaped his thoughts about money and investing. The book explodes the myth that you need to earn a high income to be rich and explains the difference between working
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What are the Construction of Transformer ? Electrical Parts / Placement of Windings in Transformer

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Windings

Electrical Parts of a transformer comprise mainly of the primary and secondary windings.
The windings consist of the current-carrying conductors wound around the sections of the core, and these must be properly insulated, supported and cooled to withstand operational and test conditions.
Copper and Aluminum are the primary materials used as conductors in power transformer windings.
These conductors may be of circular or rectangular cross-section, depending on the current and voltage ratings of the machine and are insulated using enamel, paper, or cotton.

Desirable properties of a conducting material for use in transformer ( or any Electrical Machine ) are:-
  1. High Conductivity
  2. Low temperature coefficient of resistance 
  3. High Thermal Conductivity
  4. Low coefficient of thermal expansion
  5. High ductility
  6. High tensile strength
  7. Not too heavy
  8. Low corrosion by chemicals

The two materials mostly commonly used for windings of transformers are copper and aluminum. Both have their relative merits and demerits.

Electrical conductivity of copper is higher than that of aluminum so that it offers less resistance.
Per Kg cost of aluminum is less than copper, but because of higher resistivity, the amount of material to be used to allow same amount of power loss (I^2 . R) in the winding is more if aluminum is used. 
Mechanical strength of copper is also higher than aluminum that makes copper to be more popular except for small sized ones where cost saving is one major concern.


High voltage coils are mostly made of conductors of circular cross-section so that escalation of electric field at sharp edges of the conductor can be avoided.

Low voltages coils, because of its high current rating, will generally need a number of conductors (strands) to be connected in parallel. In order to reduce the size of such stranded coil, low voltages coils are generally made of rectangular cross-section conductors.


Types of Winding

Shell type transformers use sandwich type winding with both HV and LV coils split up in a number of sections, with HV coils placed between two LV coils.

core type transformers can have the following types of windings:
  • Disc winding 
  • Helical winding
  • Double helical winding
  • Multi-layer helical winding
  • Cross over winding
The types of windings to be used depends on:
  • Current rating
  • Voltage rating
  • Short circuit strength
  • Allowable temperature rise
  • Surge current rating

Placement of Windings

There are two types of windings generally employed for Transformers. The concentric coils are used for core type of Transformers. Interleaved or Sandwiched windings are used for Shell Type Transformers.

Sandwiched windings are preferred to reduce magnetic leakage flux thereby increasing coefficient of coupling between the windings. In Sandwiched windings the Low Voltage winding is usually placed near to the core and High Voltage winding outside the Low Voltage winding. Insulation is provided between two windings and between core and winding.



Advantages of placing LV winding nearer to the core:
  • The amount of insulation required for transformer between core and winding reduced.
  • It also reduces the amount of Copper (Cu) required for windings.
  • If HV windings is outer to low voltage, then HV is accessible to provide tapings for voltage control purpose.
The directions of flux in HV and LV are of Opposing as per Lenz Law because induced emf must oppose the cause of induction.
  • If HV and LV winding are placed on same limb then they should carry 'I' in opposite directions to satisfy Lenz's law.


  • If HV and LV are placed on separate limbs, then they should carry 'I' in same direction to satisfy Lenz's law.


Related topics>>>Magnetic Parts

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