Static input variation

In power circuits and similar contexts, this refers to fluctuations in the output voltage when the load current is at its rated condition and the input voltage is gradually varied within a specified range. It is one of the indicators of stability of a power circuit against input variations. The smaller the static input variation, the higher the stability against gradual fluctuations of the input voltage over a long period. One typical application is estimating the stability of the output voltage in cases where the commercial power supply as the input gradually changes during the day due to the balance between supply and demand.