| 摘要 |
PROBLEM TO BE SOLVED: To surely detect the generation of insulation failure in an insulator provided between two heating wires. SOLUTION: A first current detecting unit 24 is interposed between one heating wire 2 and a relay contact 10 adjacent to each other through an insulator 3. A second current detecting unit 25 is interposed between the one heating wire 2 and the other heating wire 4. A control circuit 9 compares an output of the first current detecting unit 24 with an output of the second current detecting unit 25, and determines existence of unusual condition. In normal condition, output of the current detecting units 24 and 25 are the same. When an insulation failure is generated, a short-circuit is formed between both the heating wires 2 and 4, and output of the second current detecting unit 25 is lowered. When the control circuit 9 detects the generation of unusual condition, the control circuit 9 opens the relay contact 10 to stop the current to the heater 1. COPYRIGHT: (C)2005,JPO&NCIPI
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