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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 details of transformer ? Magnetic Part

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 Construction details of Transformer

Major Construction parts of a transformer can be categorized as:-

Magnetic parts

In a Transformer the primary and secondary windings are wound around the core of a transformer. Core is a magnetic material which allows the flow of magnetic flux lines to link both primary and secondary winding.

Two basic functions of the core are:
  1. To provide an easy path for the magnetic flux to flow through it, and thereby link both primary and secondary windings.
  2. To provide mechanical support for holding the coils. Both primary and secondary coils are wounded over and around the core.
There are certain properties that the core material must satisfy:
  1. Core should have low reluctance and high permeability to the flow of magnetic flux.
  2. Core is generally made of Silicon steel.

Features of Silicon Steel:
  • Ferrous Magnetic Material
  • Low reluctance and high permeability 
  • Low hysteresis coefficient (X=1.6)
               Ph = Kh . f . (Bm)^X
  • Hence, low hysteresis loss.
  • Generally, this steel is ' cold rolled grain oriented (CRGO) ' steel, to increase permeability along the direction of magnetization and reduce core losses.


→ Eddy current loss
The resistivity of core is high, due to which it cannot prevent flow of currents in small loops within the body of the core. such currents are called Eddy currents.
To restrict the flow of Eddy current through the body of the core, sheets of steel lamination are required. due to the lamination the induced eddy current is reduced, thereby reducing the eddy current loss in the core to a large extent.

The expression for eddy current loss is given by:-
Pe = Ke . f^2 . t^2 . (Bm)^2        W/m^3

Ke is constant depending on the material properties including its resistivity
f is the supply frequency
t is the thickness of each lamination 
Bm is the maximum value of flux density in the core



→ Lamination
The magnetic core is a stack of thin Silicon Steel laminations about 0.35 mm thick for 50 Hz Transformers. To reduce eddy current losses, laminations are electrically isolated from each other.

The materials used for electrical isolation are:
  1. China clay
  2. Japan Varnish
  3. Impregnated paper
  4. Oxide paints
For a laminated core we define the Stacking Factor as:

Stacking Factor=Iron Factor={Net cross-section area/Gross cross-section area}<1

Where,
Gross cross-section area (Ag): Cross-sectional Area of Magnetic material and Insulation
Net cross-section area (An): Cross-sectional Area of Magnetic material

Laminations must be tightly riveted because if there is a thin air gap between lamination then it increase reluctance path and hence increase magnetizing current for same flux.
N . Iμ = Ⲫ (constant) . R



→ Magneto-striction
Tendency of any magnetic material due to which changes in dimensions of magnetic materials take place whenever flux is flowing through it.
If laminations are not properly riveted then there may be vibrations due to this phenomenon and if frequency of vibrations fails in audible range. We can hear this and it will then produce a humming sound called as Magnetic Hum.



→ Types of Core structure
Core is generally made of Ferromagnetic Material like Silicon Steel but for high frequency Transformers core is made of Ferrimagnetic materials or Ferrites because at high frequencies eddy current losses are high and to reduce losses we need material with high resistivity called as Ferrites.

There are two types of Core structure:-



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