Electronic switch circuit and method for supply electric power to an alternative current electric furnace

The invention relates to an electronic circuit and method for supplying power to at least one electrode of an alternative current electric furnace, in particular for metal melting. The known per se circuit generally comprises a series connection consisting of a transformer for producing a supply voltage for the electric furnace from a power network (1) and an a.c. power controller (8), which is mounted between the transformer (6) and the electrode (11) and is used for controlling currents passing through the electrode (11). In order to develop such a cost-effective and constructively simple electronic circuit which prevents the a.c. power controller (8) overloading even at the electric furnace operating modes with high electrode currents, said a.c. power controller is bridged by a bridging disconnecting switch (9) which is openable or closable by means of a control device according to the value of a current flowing through the electrode (11).