| 摘要 |
PROBLEM TO BE SOLVED: To provide a protecting device for doing away with faults such as spark which tends to occur at switching operation of a contact-type circuit breaking element in a load for a direct-current circuit. SOLUTION: The protecting device 10 is structured by connecting a temperature-sensitive pellet type thermal fuse 30 as a contact type circuit breaking element between protective terminals 16, 18, and connecting a fusible alloy type thermal fuse 20 as a non-contact type circuit breaking element with the temperature-sensitive pellet type thermal fuse 30 in parallel. As to operating temperature of each fuse, that of the temperature-sensitive pellet type thermal fuse is set equivalent to or lower than that of the fusible alloy type thermal fuse, whereby, even if spark or plasma discharge is generated at operation, a non-returning protective device is provided carrying out a sure and stable circuit interruption eliminating opening troubles of a switching member such as fusing faults of movable contacts or the like. COPYRIGHT: (C)2008,JPO&INPIT
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