... ISO 9001:1994 Quality System certified GWBJ Series Medium Frequency Coreless Induction Holding FurnaceMedium Melting Equipment1.GB/T ... converter. It can change three-phase base frequency A.C power into single phase MF power with thyristor modules ... penetrating heating, quenching, pipe bending, vegetating, etc. GWBJ Series Medium-Frequency Coreless Induction Holding Furnace, Medium Melting Equipment