A Frequency Converter (AKA Frequency Changer) is a device that converts the AC of one frequency to another frequency. In addition, usually the Frequency Converter will also convert the voltage.n nA Static Frequency Converter (SFC) does this electronically without any moving parts. Before the availability of SFCs, the only way to change the frequency was by using an electro-mechanical Rotary Frequency Converter, in essence, a glorified motor generating set.n nThere are basically two types of Static Frequency Converters - those offering a variable adjustable output and those delivering a fixed output.