Glen Magnetics manufactures a wide range of ferroresonant transformers. Constant-voltage transformers are a type of saturating transformer used as a voltage regulator. Ferroresonant transformers, also known as Constant Voltage Transformers (CVTs) or ferros, produce a nearly constant average output voltage with a varying input voltage or varying load. Constant voltage transformers have wide applications, particularly where reliability and inherent regulating ability against line-voltage change are of prime importance, such as in power supplies or lighting.