根據電磁感應的基本原理，把三相工頻交流電整流后變成直流電，再將直流電變為可調節的中頻電流，供給由電容和感應線圈組成的負載（線圈和電容可并聯，也可串聯），在感應圈中產生高密度的磁力線，并切割感應圈里盛放的金屬材料，在金屬材料中產生很大的渦流。這種渦流同樣具有中頻電流的一些性質，即，金屬自身的自由電子在有電阻的金屬體里流動要產生熱量。例如，把一根金屬圓柱體放在有交變中頻電流的感應圈里，金屬圓柱體沒有與感應線圈直接接觸，通電線圈本身溫度已很低，可是圓柱體表面被加熱到發紅，甚至熔化，而且這種發紅和熔化的速度只要調節頻率大小和電流的強弱就能實現。如果圓柱體放在線圈中心，那么圓柱體周邊的溫度是一樣的，圓柱體加熱和熔化也沒有產生有害氣體、強光污染環境。
According to the basic principle of electromagnetic induction, the three-phase power frequency alternating current is rectified and converted into direct current, which is then converted into adjustable intermediate frequency current to supply a load composed of a capacitor and an induction coil (the coil and capacitor can be connected in parallel or in series). High density magnetic lines of force are generated in the induction coil, and the metal material contained in the induction coil is cut, generating large eddy currents in the metal material. 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. 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.