Furnace with level detection system

An electric furnace comprising:

• at least one electrode;
• a vessel comprising a base, at least one sidewall and a roof region comprising a roof, the vessel holding a body of material to be processed, the vessel having a centre axis extending between the roof and the base and the body of material comprising at least one layer having an upper surface, the at least one electrode extending through the roof into the vessel;
• and
• at least one non-contact sensor for sensing a distance between a reference point and a position on the upper surface, the non-contact sensor comprising an electromagnetic signal transceiver device, an antenna located spaced above the upper surface in the roof region of the furnace and a signal guide extending between the electromagnetic signal transceiver device and the antenna and wherein the transceiver device is located externally to the vessel at a predetermined position where at least one of the vessel and distance attenuates electromagnetic interference (EMI) inside the vessel to such an extent that an EMI shield for the transceiver device over and above an original manufacturer housing for the transceiver device is dispensed with.

A method of operating an electric furnace comprising a vessel comprising a base, at least one sidewall and a roof region comprising a roof, the vessel holding a body of material to be processed, the body of material comprising at least one layer having an upper surface;

• at least one electrode extending through the roof into the vessel;
• and at least one non-contact sensor for sensing a distance between a reference point and a position on the upper surface, the non-contact sensor comprising an electromagnetic signal transceiver device, an antenna located spaced above the upper surface in the roof region of the furnace and a signal guide extending between the electromagnetic signal transceiver device and the antenna, the method comprising:
• locating the transceiver device externally to the vessel;
• and
• utilizing the signal guide and at least one of the vessel and distance to the transceiver device to attenuate electromagnetic interference (EMI) existing inside the vessel to such an extent that at the transceiver device no EMI shield for the transceiver device over and above an original manufacturer housing for the transceiver device is provided.