| 摘要 |
PROBLEM TO BE SOLVED: To prevent a feed stop to a protection object due to an SPD trouble by operating an interrupter at a speed faster than an input breaker for the protection object without depending upon the status (a resistance value) of the SPD when the SPD deteriorates and gets trouble. SOLUTION: When a thunder surge current flows through a feeder 4-3 or 4-1, the thunder surge current flows to a (an apparatus) ground by the low resistances of the SPD 1-1 or 1-2 and corresponding switching type SPD 5-1 or 5-2, and the thunder surge current is allowed to escape normally to the ground. When the SPD 1-1 deteriorates and reaches the low resistance, a voltage is generated between a branch point and a neutral conductor 4-2. Since the interrupter 8-1 has a smaller rated current than the input breaker 3, a switch 7-1 is interrupted by detecting the voltage by a driver 6-1 prior to the interruption operation of the input breaker 3, and the troubled SPD 1-1 is detached from the feeder 4-3. COPYRIGHT: (C)2010,JPO&INPIT
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