# Voltage Regulation in Transformer

Apr 28 • General • 5762 Views • 2 Comments on Voltage Regulation in Transformer

Voltage Regulation in Transformer

Definition of Voltage Regulation:

• The Voltage Regulation is defined as the voltage difference between no   load and full load voltages of a transformer with respect to its full load voltage.
•   This is usually expressed in terms of percentage.

Expression of Voltage Regulation of Transformer:

• Due to the voltage drop across primary and secondary impedences, it is observed that secondary terminal voltage drops from no load value(E2) to full load.
•  This decrease in secondary terminal voltage expressed as a fraction of no load secondary voltage called regulation of a transformer.
•  Let,

E2=secondary terminal voltage on no load

V2=secondary terminal voltage on full load

Mathematically, voltage regulation can be expressed as,

Voltage regulation(%)=(E2-V2)/V2*100

The ratio (E2-V2)/V2 is per unit regulation.

•  As load current increases,the voltage drop tends to increase V2 and drops more and more.
•  In case of lagging power factor V2<E2 ,we get positive voltage regulation but in case of leading power factor E2<V2,we get negative voltage regulation.

Voltage Regulation of Transformer at Lagging Power Factor:

Voltage Regulation(%) = {(E2-V2)/V2}*100%

= {(I2R2COSθ2+I2X2Sinθ2)/V2}*100%

Voltage Regulation of Transformer at Leading Power Factor:

Voltage Regulation(%) = {(E2-V2)/V2}*100%

={(I2R2Cosθ2-I2X2sinθ2)/V2}*100%

Q1.Define Voltage Regulation.

Ans.   The Voltage Regulation is defined as the voltage difference between no load and full load voltages of a transformer with respect to its full load voltage. This is usually expressed in terms of percentage.

Q2.Write the expression of voltage regulation of transformer.

Ans.  Let,

E2=secondary terminal voltage on no load

V2=secondary terminal voltage on full load

Mathematically, voltage regulation can be expressed as,

Voltage regulation (%)= (E2-V2)/V2*100

The ratio (E2-V2)/V2 is per unit regulation.

Q3.What is the voltage regulation of transformer in case of lagging and leading power factor?

Ans. Voltage Regulation of Transformer at Lagging Power Factor:

Voltage Regulation (%) = {(E2-V2)/V2}*100%

= {(I2R2COSθ2+I2X2Sinθ2)/V2}*100%

Voltage Regulation of Transformer at Leading Power Factor:

Voltage Regulation (%) = {(E2-V2)/V2}*100%

= {(I2R2Cosθ2-I2X2sinθ2)/V2}*100%