| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent beforehand an occurrence of an accident such as blackout, electric shock or the like during inspection and maintenance work by confirming a voltage condition of a system and opening and closing an electric power switch when one checks a functional work of the electric power switch. Ž<P>SOLUTION: A voltage display unit 6a is provided on an electric power switch 1a, and when a push button 9 of the voltage display unit 6a is pushing-operated, the unit 6a displays whether a power source voltage is impressed on a primary side of A-phase power line 2, B-phase power line 3, C-phase power line 4 composing a three-phase power line, by presence/absence of lighting up of each of neon lamps 11. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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