When silicon carbide rods are used for a long time, some are damaged and need to be replaced, new rods should be replaced according to the increase in resistance by matching group’s requirements. If the rods in the furnace are damaged more, or the resistance value increases too much, the silicon carbon rods should all be replaced. The electric furnace using silicon carbon rods for the first time, if it have broken rods after a period of time, the rods should be replaced as a whole. The replaced old rod is used to replace the broken rod which will be generated in the future use. When replacing, you should select a rod with a resistance close to the broken rod.