| 摘要 |
PURPOSE:To obtain a self-return type overcurrent indicator eliminating any auxiliary power source by performing indication instantaneously by an electromagnetic force for overcurrent while it is returned with delayed characteristics with a bellows, a back valve and a pore. CONSTITUTION:When no overcurrent flows through a through conductor 8, a mobile core 13 is at the rest position separated by a gap g from fixed cores 4 and 5 by a force of a return spring 18, where no indication of overcurrent is made. As overcurrent runs, the mobile core 13 is attracted by the fixed cores 4 and 5 against the force of the spring 18 and a bellows 14 is compressed in linkage therewith. When the overcurrent stops running through the conductor 8, the mobile core 13 is caused to return to the rest position by the force of the spring 18. But the expanding action of the bellows 14, namely, the return action of the mobile core 13 is done slowly -- not instantaneously -- for 1-2hr, as the bellows 14 provided following the mobile core 13 has a back valve 30 and a pore mechanism through a communicating hole 22. This permits a worker to check it visually with ease even after the cutting of the overcurrent. |
