中频感应加热炉是一种将工频50HZ交流电转变为中频(300HZ以上至20K HZ)的电源装置，把三相工频交流电，整流后变成直流电，再把直流电变为可调节的中频电流，供给由电容和感应线圈里流过的中频交变电流，在感应圈中产生高密度的磁力线，并切割感应圈里盛放的金属材料，在金属材料中产生很大的涡流。这种涡流同样具有中频电流的一些性质，即，金属自身的自由电子在有电阻的金属体里流动要产生热量。
The medium frequency induction heating furnace is a power supply device that converts 50 Hz AC power into medium frequency (from 300 Hz to 20K Hz). It converts three-phase AC power into DC power after rectification, and then converts DC power into adjustable medium frequency current to supply the medium frequency AC current flowing through the capacitor and induction coil, generating high-density magnetic lines in the induction coil and cutting the metal materials contained in the induction coil, Generate large eddy currents in metal materials. This type of eddy current also has some properties of intermediate frequency current, that is, the free electrons of the metal itself flow in a resistive metal body to generate heat.
例如，把一根金属圆柱体放在有交变中频电流的感应圈里，金属圆柱体没有与感应线圈直接接触，通电线圈本身温度已很低，可是圆柱体表面被加热到发红，甚至熔化，而且这种发红和熔化的速度只要调节频率大小和电流的强弱就能实现。如果圆柱体放在线圈中心，那么圆柱体周边的温度是一样的，圆柱体加热和熔化也没有产生有害气体、强光污染环境。中频电炉广泛用于有色金属的熔炼
For example, if a metal cylinder is placed in an induction coil with alternating intermediate frequency current, and the metal cylinder is not in direct contact with the induction coil, the temperature of the energized coil itself is already very low. However, the surface of the cylinder is heated to redness or even melting, and the rate of redness and melting can be achieved by adjusting the frequency and current strength. If the cylinder is placed in the center of the coil, the temperature around the cylinder is the same, and the heating and melting of the cylinder do not produce harmful gas or strong light to pollute the environment. Medium frequency electric furnaces are widely used for smelting non-ferrous metals