| 摘要 |
PROBLEM TO BE SOLVED: To prolong service life of a lightning arrester by effectively utilizing parts when being employed at 100 V in single-phase two wires. SOLUTION: A lightning arrester 1 is provided with a lightning tube 6 connected to a grounding terminal 5, varistors 7-9 connected between power supply terminals 2-4 and the lightning tube 6, varistors 10-12 connected between respective phases, fuses 13 and 14 connected between power supply terminals 2 and 4 of an L1- and L2-phases and varistors 7 and 9, light-emitting diodes 15 and 16 connected between output ends and N phases, a coil 17 of a relay connected between the output end of the fuse 13 in the L1-phase and N phase, a b contact 18 and a switch 19 of the relay connected in series between input ends of the fuses 13 and 14, a power supply line connected with L1- and L2-phase power supply terminals 2 and 4 when being employed at 100 V in single-phase two wires. Even if the varistor 10 is broken by lightning surge, the b contact 18 is turned on, and current is conducted is switched between the L2-N phases to be usable again, as an arresters.
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