| 摘要 |
PURPOSE:To prevent breakdown of an electric power control element and also to prevent danger such as abnormal heating and a fire of a heating element by detecting the overvoltage when it is applied, and cutting off an interposed switch. CONSTITUTION:In case when an electric power source 2 is normal, when an electric power source switch 24 is turned on, an electric power control element 3 conducts and a heating element 1 is electrified. When a temperature rises, the electric power control element 3 is cut off, and is held at a set temperature of the heating element 1. In case when the electric power source 2 has overvoltage, it is detected by an overvoltage detecting part 7, a resistance 16 is heated, a temperature fuse 23 is fused, and connection with the electric power source 2 is cutt off. |
