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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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Electrical Braking of DC Motors

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Regenerative Braking

  • In this form of braking, an attempts is made to return the stored Kinetic Energy of rotor back to source as much as possible.
  • Braking can be achieved by keeping Ea > V either by increasing excitation or by reducing terminal voltage.
  • This would result in reversal of armature current and reversal of direction of torque and sends the machine to generator mode but machine cannot keep running as there is no Prime Mover to supply mechanical power.
  • But armature current must be kept within limits and as soon as Ia = 0, machine must be switched off.

Plugging

  • In this technique, supply to armature terminals is reversed while field is left undisturbed.
  • The current reverses resulting in to negative torque that brings the rotor quickly to rest and the supply in the motor should then be switched off to prevents its rotation in reverse direction.
  • During plugging armature current should be maintained within safe limits by inserting an external resistance in the armature circuit or by adjusting the value of supply voltage.
       Armature Current under Plugging condition is given by,  Ia' = (Vt + Eb) /(Ra + Rext)
      
       The expression for Plugging Torque is given by, Tplugging = Eb Ia' /ω

       The Load Torque under normal running conditions is given by, TLoad = Eb Ia /ω
              where, Ia = (Vt - Eb) /Ra  is the armature current before plugging.

       The net Braking Torque on motor is given by, TBraking = TPlugging + TLoad

  • During plugging, electrical power is taken from the mains and mechanical power is derived from shaft and sum of these 2 powers dissipates at heat in the rotor. Precaution must be taken so that developed heat may not destroy the rotor.

Dynamic (Rheostatic) Braking

  • Armature supply is replaced by a resister.
  • So machine goes into generator mode and extracts mechanical power from the shaft bringing the motor to stand still.
  • Braking can be made faster by increasing RL or decreasing If  or both.



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