Voltage regulator booster transformer

The step voltage regulator consists of an autotransformer with continuously variable transformer ratio. The voltage intake varies depending on the contact position; therefore the voltage supplied to the transformer primary winding also varies. The voltage across the regulator contacts (and consequently that on the secondary winding of the high voltage auto load booster transformer) is either in phase or in opposition to the supply voltage, and it is therefore added or subtracted to the supply voltage, thus compensating its variations.