Abstract: A method and an apparatus for automatically detecting the intactness of ground electrodes in the bath of an induction furnace are described. According to the method a low DC or AC current is applied to an additional insulated electrode extending through the furnace bottom and being in connection with the melt. After melting of the charge this current is measured and compared with a reference value. If the magnitude of the current drops below the reference value an alarm signal is generated. Furthermore, methods and devices for localizing a ground fault are described. By this, the security of the operation of an induction furnace is improved.

Abstract: An apparatus for detecting ground faults in a multifurnace installation with at least two induction furnaces and a multifurnace installation are described. A ground-fault sensor is associated with each induction furnace and is connected to the electrical supply line to the induction furnace coil. Furthermore, the apparatus has a ground-leak sensor. Moreover, the apparatus includes an additional ground-fault sensor that measures at the same location as the ground-leak sensor. In this manner an improvement of security during the operation of the system is obtained.

Abstract: An apparatus for detecting ground faults in a multifurnace installation with at least two induction furnaces and a multifurnace installation are described. A ground-fault sensor is associated with each induction furnace and is connected to the electrical supply line to the induction furnace coil. Furthermore, the apparatus has a ground-leak sensor. Moreover, the apparatus includes an additional ground-fault sensor that measures at the same location as the ground-leak sensor. In this manner an improvement of security during the operation of the system is obtained.

Abstract: A method and an apparatus for automatically detecting the intactness of ground electrodes in the bath of an induction furnace are described. According to the method a low DC or AC current is applied to an additional insulated electrode extending through the furnace bottom and being in connection with the melt. After melting of the charge this current is measured and compared with a reference value. If the magnitude of the current drops below the reference value an alarm signal is generated. Furthermore, methods and devices for localizing a ground fault are described. By this, the security of the operation of an induction furnace is improved.