| 摘要 |
<p>1492369 Seaming non-metallic sheet material MESSER GRIESHEIM GmbH 1 Oct 1976 [4 Oct 1975] 40822/76 Heading B5K A device for butt welding tubes comprises an electrically heated element 11 connected via a control unit 12 to a source 5 of electric current, a fault current circuit-breaker 13 being provided in the unit 12. In the embodiment described, the unit 12 contains switch-on protection, a control for regulating the temperature of the element 11, and the fault-current circuit-breaker 13, the latter consisting of a switch 14 having a switching lock 15, a release 16, a secondary winding 17 (release coil of the converter), a converter 18 with primary windings, a test button 19 and a test resistor 20. The primary windings of the converter 18 are connected to the source S, i.e. the local supply mains, and to the element 11. A protective conductor 21 is connected to the element 11 and via conductors 22a, 22b and a test switch 23 to an earthing rod 24. A conductor 25 connects the conductor 21 to the circuit-breaker 13. The switch 20 is arranged in the unit 12 and has two resting contacts and one working contact.</p> |
