HEAT TREATING FURNACE

PURPOSE:To eliminate the instability of controlling a power source by hanging a cylindrical housing from the outer wall of a furnace by an insulating coupler, and securing a furnace core heater through a heat resistant porcelain to the housing, thereby obviating a leakage current. CONSTITUTION:The double tubes of a cylindrical housing 2 and a furnace outer wall 4 commonly having a furnace core 7 are electrically insulated therebetween by a high heat resistant coating tube 11 and nichrome screws 12 passing the tube 11. A furnace core heating wire 13 is inserted into a porcelain 8 of C- shaped section. According to this construction, the screws 12 are electrically high resistive, thereby suppressing a leakage current based on a thermal potential caused by the temperature difference between the housing 2 and the outer wall 4. The porcelain 8 cuts off a power source voltage leaked from the wire 13 to prevent the currents from creeping to the housing 2 side. Accordingly, the unstability of operating to control the power source voltage due to the currents can be eliminated.