| 摘要 |
PURPOSE:To protect the communication equipment from a lightening surge or the contact of commercial lines by providing a lightening surge protecting element and a communication device adaptor and arranging the communication device adaptor in a way that a fuse is blown by a heat caused in a resistor due to an overcurrent. CONSTITUTION:The titled circuit consists of a protective element 3 provided to a communication equipment 1 and an adaptor 4a provided to the input section of the communication equipment 1. The protective element 3, in the event of occurrence of a lightening surge over a signal line 51, absorbs the surge voltage and clamps the voltage to a constant voltage. A fuse 6 is a temperature fuse and arranged while being coupled thermally closely with the resistor 5a. If an overcurrent flows through the resistor 5a because of contacts of commercial lines, the resistor 5a is heated excessively, the heat blows the fuse 6 completely. Thus, the invasion of a lightening surge, a contact voltage between commercial lines or invasion of current is protected completely.
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