1. Direct benefit: Enhances the efficiency in the intermediate frequency smelting process, firstly, it has save 2% active power; secondly, it can shorten the smelt time comparatively. It compensates the lag reactive power which the movement produces effectively, reduce the total apparent current. 2. Indirect benefit: Lengthens service life of the electric equipment, such as circuit breaker (Air-break); lengthens the user service life of the transformer, reduces the maintenance cost. Technical service The Harmonic control process is: Carries on the scene of survey intermediate frequency stove to the user to move various stages Harmonic quantity and various electrical parameters→ design filter installment capacity→ manufacture→ the scene of installation and debugging→ track and examination→ adjustment→ to record the scene test date→ approval.