How does a regulating ferroresonant transformer work?
Regulating transformers operate on a resonant principle. The resonant network added to the transformer consists of a capacitor and inductor connected in parallel, which in turn is connected in series to the load. This type of transformer is generally 4 or 5 times larger physically than an equal size 2 winding transformer. The price also, is more than a nominal type transformer. Ferroresonant transformers are used in locations where it is important that there be practically no voltage variation. A typical example of the regulation of this type of transformer is 1% variation in output against plus/minus 20% variation in input. Ferroresonant transformers are commonly used in filaments on oscillator tubes in radio or similar type circuit, and lamps used for picture development work where light output is very critical. One of the common objections to this type of transformer is that the output voltage wave is distorted and resembles a wave with a square top. Where a harmonic free sine wave
