Constant voltage transformers are used to provide stable voltage and protect equipment from power fluctuations. They work on the principle of ferroresonance to maintain a constant output voltage between 220v +/-1% by saturating the magnetic core under the secondary winding. A capacitor is connected across the secondary winding to filter the output voltage close to a square wave at 50Hz. Power Engineers manufactures constant voltage transformers with high reliability, efficiency, and rugged industrial designs to provide voltage regulation and protection for various industries.