| 摘要 |
<p>PURPOSE:To secure excellent property of safety and reliability by a method wherein miniaturization and simplification of constitution are contrived and faulty throwing of an earth switch is prevented during ordinary operation. CONSTITUTION:This device is equipped with a liquid pressure cylinder 3 for opening and/or closing an earth switch 2, a pressure fluid supplying device 4 having a cylindrical body 9 and a low pressure tank 5. Two pieces of pistons 10, 11 connected together are mounted slidably in the cylindrical body 9. A liquid pressure fluid chamber 14 is provided between the piston 11 connected to a breaker operating unit and the closing end of the cylindrical body 9, a first valve 20, opened when the liquid pressure in the liquid pressure fluid chamber 14 has exceeded a predetermined pressure, is provided between the liquid pressure fluid chamber 14 and the liquid pressure cylinder 3 while a second valve 21, opened when the liquid pressure in the liquid pressure fluid chamber 14 has been reduced than an atmospheric pressure, is provided between the liquid pressure fluid chamber and a low-pressure tank 5.</p> |
