Impedance voltage in electrical power transformer

The impedance of a transformer is expressed in terms of impedance voltage.
It is defined as the voltage required to be applied to the line terminals of a winding to cause rated current to flow through these terminals, with the terminals of other winding being short circuited.
It is also called short circuit voltage (Vsc)
The value is related to reference temperature
It is determined by conducting short circuit test & Expressed as % of rated voltage, % impedance in the range of 4.5% to 15%

Significance of Impedance voltage

Determines the regulation and efficiency of a transformer
Its high value means higher impedance, higher voltage regulation, higher losses and lesser efficiency.

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