Ferroresonant transformers provide a stable power output (typically ±3%) for input voltages that vary as much as ±15%. Models are available for 50 Hz, 60 Hz, and 50/60 Hz, with output ratings from 50 VA to 5.0 kVA. Standard square wave output requires less filtering than linear transformers for dc applications.
Ferroresonant transformers provide a stable power output (typicallyliability under extreme operating conditions. Devices are suited for use in battery chargers, inverter and UPS systems, line voltage stabilizers, industrial automation and machine tools, and other applications that require stable output with a high degree of isolation from line disturbances. www.foster-transformer.com Foster Transformer