brief introduction: Open: the main electrode connection piece, igniter connection piece, rod-shaped resistor, insulating connecting rods and bimetallic strip, which described the main electrode connecting piece and the igniter connection piece described by the insulation of the connection rod fixed connection, one end of the bimetallic strip and described the main electrodes described by rod-shaped resistor fixed connection, on the other side of the bimetallic strip and igniter connector at one end of the room temp