| 摘要 |
Subject: automatism for avoiding perforation of metal water piping by drilling-digging electric tools.Constitution: in-series connection of a relay 5, a power source 6, a led 9 and a safety fuse 10. The automatism in question is incorporated (during construction or later) to whatever electric drilling or digging tool powered by the mains or by battery and is initiated to stop the operation of the drilling-digging tool 1 before destroying the metal water pipe 12. |
