Constant voltage transformer
Voltage regulator § Constant-voltage transformer
By arranging particular magnetic properties of a transformer
core, and installing a ferro-resonant tank circuit (a capacitor and an
additional winding), a transformer can be arranged to automatically keep the
secondary winding voltage relatively constant for varying primary supply
without additional circuitry or manual adjustment. Ferro-resonant transformers
run hotter than standard power transformers, because regulating action depends
on core saturation, which reduces efficiency. The output waveform is heavily
distorted unless careful measures are taken to prevent this. Saturating
transformers provide a simple rugged method to stabilize an AC power supply.