The conductor itself is heated by the thermal effect of the induced current (eddy current) generated by the conductor in the alternating electromagnetic field. How about cast aluminium heating ring? According to different heating process requirements, the frequency of AC power supply used in induction heating includes power frequency (50-60 Hz), intermediate frequency (60-10 000 Hz) and high frequency (higher than 10 000 Hz). The power frequency power supply is the AC power supply which is usually used in industry. The power frequency of most countries in the world is 50 Hz. The voltage applied to the induction device by the power frequency power supply for induction heating must be adjustable. According to the power of heating equipment and the capacity of power supply network, high-voltage power supply (6-10 kilovolts) can be used to supply power through transformers, and heating equipment can be directly connected to 380 volts of low-voltage network.

Medium frequency power supply used to use medium frequency generator set for a long time. It consists of an intermediate frequency generator and a drive asynchronous motor. The output power of this unit is generally in the range of 50-1000 kW. With the development of power electronics technology, high frequency power supply in thyristor frequency converter is used. This kind of medium frequency power supply uses thyristor to convert AC power into DC power, and then DC power into AC power of desired frequency. Because of its small size, light weight, no noise and reliable operation, this kind of converter has gradually replaced the intermediate frequency generator set.