Advanced high powered converter system for vacuum induction furnaces

Vacuum induction melting is a commonly used secondary metallurgy process for the production of extraordinarily pure metals. The vacuum level of such installations in a range of 10-1 to 10-5 mbar leads to a dielectric strength which is considerably lower than under atmospheric pressure. Because of this, the voltage of current-carrying parts is limited to around 600 V. That is the condition for the coil of Vacuum Induction Furnaces, too, so that high power output necessitates a high current level. Particular requirements on the converter technology are the result of that. In the following, an advanced converter system is described which supplies 4,000 kW at 600 V without an MF-transformer for one 8 t and one 17 t Vacuum Induction Furnace at Böhler Edelstahl in Kapfenberg, Austria