Voltage Regulation in Transformer

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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%

Some related Questions and Answers

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%

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