Stepless AC voltage control — from 0V to full output, with one dial.
A variable auto-transformer — commonly called a variac — uses a rotating carbon brush contact on a toroidal CRGO winding to tap off any fraction of the supply voltage as output. Unlike a fixed-ratio transformer, it gives the user continuous control from 0V up to 270V (single-phase) or 430V (three-phase) without the steps and dead-bands of a tap-changer. This makes it the standard tool for test benches, laboratory power supplies, heating element control, and any process where the exact applied voltage must be dialled in and held stable.
Sakthi manufactures single and three-phase variacs on toroidal CRGO cores — the toroidal form minimises leakage flux and gives a more uniform regulation across the output range than a stack-type winding. The carbon brush is hardened for long contact life, and the winding is enamelled copper for low resistance and efficient operation. Rated current ranges from 2A to 260A per phase, with the thyristor-controlled version available for remote or programmatic voltage setting.
Typical applications
Provides continuously variable AC voltage for component testing, calibration, and high-pot testing in R&D labs.
Adjusts heating element power in industrial ovens, furnaces, and soldering stations by controlling applied voltage smoothly.
Controls single-phase fan and motor speed, and lamp brightness in workshops, test setups, and lighting labs.
Used by power quality engineers to simulate voltage sag and swell conditions for equipment immunity and compliance testing.
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