LIGHTNING-PROTECTION METHOD FOR PLURAL COMMUNICATION DEVICES USING AC POWER SUPPLY

摘要

PURPOSE:To prevent lightning surge voltage from being generated between unspecific communication devices even in a communication system, where plural communication devices are connected, by providing precedence in arrester operating voltage of the communication device and further specifying the method of connecting a grounding cable to the earth from the communication device. CONSTITUTION:In the case of a lightning surge intruding from an AC power line 3, lightening surge voltage is applied between the AC power line 3 and internal circuits 1-1, 8-1 or earth terminals 1-2, 8-2. However, since an arrester 5-1 of the lowest operating voltage is set In a primary communication device 1, this arrester 5-1 is first operated. in the case of a lightning surge intruding from a communication cable 2, the lightning surge is allowed to flow out to the earth 7 from a grounding point of the primary communication device 1, but potential is generated between the AC power line 3 and the earth terminals 1-2, 8-2 by the increasing potential at the grounding point. However, also in this case, the lightning surge, passing through the arrester 5-1, is allowed to flow out.