__TRANSFORMER ON LOAD__**The Transformer is said to be loaded, when it's secondary Circuit is complete through an impedance or load. The magnitude and phase of secondary Current [ i.e., Current following through secondary ] I2 with respect to secondary terminals depends upon the characteristic of the load i.e., Current I2 will be in phase lag behind and lead the terminal Voltage V2 respectively when the load is non- inductive, inductive and capacitive. The net flux passing through the core reamins almost constant from no load to full load irrespective of load conditions and so core losses remain almost constant From no load to full load. Phaser diagram for an ideal Transformer supplying inductive load in shown in fig**.

**The Primary Current,**

**I1 = I1 + I0 = KI2 + I0**

__RESISTANCE AND LEAKAGE REACTANCE__

**In actual practice, both of the primary and secondary windings have got some ohmic resistance causing voltage drops and copper losses in the windings.**

**In actual practice, the total flux created does not Link both of the primary and secondary windings is but devided in to Three components namely the main of mutual fluxÎ¦ Linking both of the primary and secondary winding, primary leakage flux Î¦L1 linking with primary winding only and secondary leakage flux Î¦ L2 linking with secondary winding only. The primary leakage flux Î¦ L1 is Produced by Primary amps turns and is Proportional to primary Current, number of primary turns being fixed. The primary leakage flux Î¦ L1 is in phase with I1 produces and self induced EMF EL1 given as 2Ï€fL1 I1 in the primary winding. The self induced EMF devided by primary current gives the reactance of primary and is denoted by X1.**

**EL1 2Ï€fL1 I1**

**i.e., X1 = ------ = -------------- = 2Ï€fL1**

**I1 I1**

**Similarly leakage reactance of secondary**

**EL2 2Ï€fL2 I2**

**X2 = ------- = --------------- = 2Ï€fL2**

**E2 I2**

**A Transformer with magnetic leakage and winding resistance is equivalent to an ideal Transformer ( having resistance and leakage reactance ) having inductive and resistive coils connected in series with each winding as shown in fig.**

**When a practical Transformer is loaded**

**Induced EMF is Secondary winding**

**E2 = V2 + I2 ( R2 + jX2 ) = V2 + I2 Z2**

**Induced EMF in primary**

**E1 = E2 / k**

**And applied voltage to primary winding**

**V1 = -E1 + I1 ( R1 + jX1 ) = -E1 + I1 Z1**

__EQUIVALENT RESISTANCE AND REACTANCE__

**The Equivalent resistance and Reactances of Transformer referred to primary and secondary sides are given as follows;**

**Referred to primary Side**

**R2**

**Equivalent Resistance R01 = R1 + -------**

**K^2**

**X2**

**Equivalent Reactances X01 = X1 + -------**

**K^2**

**Referred to Secondary side**

**Equivalent Resistance R02 = K^2 R1 + R2**

**Equivalent Reactance X02 = K^2 X1 + X2**

**Where K is Transformation ratio.**

**Approximate Voltage drop in the transformer referred to Secondary**

**= I2 ( R02 Cos**

*Î¦*

*+- X02 sin*

*Î¦*

*)*

*+ Ve sign for lagging power factor and -Ve sign leading power factor.*

**EQUIVALENT CIRCUIT**

**The Equivalent Circuit of any device can be quite helpful is predetermination of the behavior of the device under various condition of operation and it can be drawn if the equations describing it's behavior are known.**

**Equivalent Circuit of a transformer having Transformation ratio**

**E2**

**K = ------- is shown in fig.**

**E1**

**Transformer Related more knowledge**

**So click the link**

**[ Transformer Basic Knowledge A ]**

**[ Transformer Types B ]**

## 0 Comments