previous post

RICH DAD POOR DAD BOOK REVIEW

-
  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
Post a Comment

Ideal Transformer (1-Phase) Operation Under No-Load

-

What is Ideal Transformer ?

An ideal transformer is a transformer with the following assumptions:
  • Permeability of transformer is infinite.
  • Iron loss in the transformer core are zero.
  • Resistance of transformer winding is zero.
  • No magnetic leakage flux, so coefficient of coupling is 1.
  • Magnetization curve of transformer is linear.

Operation of Ideal transformer under No-Load

1-Phase transformer will have two coils, the primary and the secondary. The primary winding is supplied from an AC voltage source, while secondary winding terminals are connected to the load. By electrical load, it is meant the output current and thus no-load means that the output current is zero, i.e., the secondary terminals are open circuited.

Schematic diagram of an ideal, single-phase transformer operation under no-load


The output (secondary) current of a 1-Ⲫ transformer is   I2 = V2 / ZL  
Where,     V2 = Secondary terminal voltage
                 ZL = Load impedance connected across secondary terminals

Thus, at no-load when I2 = 0, it means that ZL → ∞
i.e., the transformer secondary terminal are open circuited.

When the primary winding of a transformer is connected to an AC voltage source, and the secondary winding terminal are kept open circuited, the transformer is said to be operating at no-load. 
Such an ideal transformer under no-load is schematically shown in above figure.


For a sinusoidal input, current in the primary winding is: i1 = Im . Sin(ωt)
Flux is also sinusoidal , Ⲫ = Ⲫm . Sin(ωt)
Self-induced EMF in the primary winding:  e1 = Em1 . Sin(ωt - 90°)
Thus, the induced EMF E1 in the primary winding lags behind the mutual flux Ⲫ by 90° in phase. 
According to Lenz's law, this induced EMF must oppose the supply voltage V1 . For an ideal transformer, since the winding impedance is neglected, this self-induced EMF in the primary winding will be exactly equal and opposite to the supply voltage, i.e., V1 = -E1 , which means they are exactly opposite in phase, i.e., at 180° with respect to each other.


Note that the same flux Ⲫ links with the secondary coil also and induces a mutually induced EMF in the secondary winding. Value of this secondary EMF is: e2 = Em2 . Sin(ωt - 90°)
Thus, E2  also lags behind the flux  Ⲫ  by  90°  and the two EMFs  E1  and  E2  are in the same phase. with the secondary terminal open circuited, V2 = E2 .
Note that the two EMFs  E1  and  E2  are related by the turns ratio:
E1 / E2 = N1 / N2 = a

Diagrammatically, some of these quantities are represented in below figure.

Signals in a 1-phase transformer


Phasor diagram for the ideal transformer under no load involving the quantities describe above is shown in below figure:-

Phasor diagram of ideal transformer operation under no-load



Comments

Post a Comment

If you have any doubts, please let me know

Popular posts from this blog

Ideal Transformer (1-phase) Operation Under Load

-
Image
 What is Ideal Transformer ? An ideal transformer is a transformer with the following assumptions: Permeability of transformer is infinite. Iron loss in the transformer core are zero. Resistance of transformer winding is zero. No magnetic leakage flux, so coefficient of coupling is  1 . Magnetization curve of transformer is linear. Operation of Ideal transformer under load Schematic diagram of an ideal, 1-phase transformer under load When a finite impedance load Z L   is connected across the secondary terminals of a 1-phase transformer as shown in above figure, the load current I 2   flows through the secondary winding and the load. load current I 2   is given by:- I 2  = V 2 / Z L How will MMFs Produce ? A voltage source V 1   is connected to the primary winding. Due to this voltage V 1  primary current I 1   flowing through N 1   number of turns in the primary winding produces an MMF  N 1 .I 1   which creates the flux Ⲫ in the core. This flux links with the secondary coil and induc
Read more

RICH DAD POOR DAD BOOK REVIEW

-
  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
Read more

Compensating Winding

-
Image
Compensating Winding The cross magnetizing armature reaction effect that causes concentration of flux under one pole tip is caused mainly by the conductors that lie under the pole are. When the machines are heavily loaded, the flux density at these tips become very high resulting in higher than normal induced voltage between concerned adjacent commutator segments. This may cause a spark over between adjacent commutator segments more so because these coils are physically close to the commutation zone where air temperature is high and favorable for spark over. This may lead to other segments also getting involved and resulting in fire over entire commutator segment. Also if load is rapidly fluctuating (e.g. rolling machine), L(di/dt) voltage of coils may became high enough to start a spark over between adjacent commutator segments. This phenomenon will start from the coil under the pole center and it would have maximum. This problem is more acute when load is decrea
Read more