What's the difference between a transformer and a solid state converter? The important difference is how the device converts voltage.

The household electricity our North American appliances use is delivered at 120VAC (volts alternating current) 60 Hz (60 cycles/second). When the electric current flows it rises from 0 volts to 120 volts back to 0 volts and then it falls to negative 120 volts and rises back to 0 volts. This rise and fall completes one cycle (1 Hz) and is called a "sine wave." To convert 240VAC to 120VAC, for example, a transformer reduces the height of the 240 volt sine wave in half, creating a 120 volt sine wave that can be safely used by all types of 120VAC appliances, while a solid state converter chops the sine wave at its positive and negative 240 volt peak, reducing the power in half but creating a chopped waveform that can ONLY be used by NON-ELECTRONIC heating appliances.

NOTE: Transformers and solid state converters do not convert cycles (60 Hz North America vs. 50 Hz overseas).