FIXED output voltage that REMAINS constant for any changes in load CONDITIONS or INPUT voltage, i.e. it regulates or maintains a constant dc output voltage in spite of the fluctuations in ac input voltage or load current.Voltage regulation is a measure commonly used to describe the percentage voltage difference between no-load and full load voltages to the full load voltage for ELECTRICAL machines.\(V.R. = \frac{{{V_{nl}} - {V_{fl}}}}{{{V_{fl}}}} \times 100\)The ideal voltage regulation for any machine should be zero.Zero voltage regulation indicates that there is no difference between its no-load voltage and its full-load voltage.This is not practically possible and is only valid theoretically for ideal machines.Therefore, for the practical application, it should be as low as possible for the proper operation of the electrical devices.