Patent PL-157915-B1 (PL)
Title: Method for assembly of precast heads on electric power cables with screen moulded on insulation
IPC: H02G15/02
Filed: 1988-06-28
Abstract: 1. A method for assembling prefabricated heads, specifically on electromagnetic cables having their insulation screen extruded, by first removing from the cable part of its protective covering, leading the return conductor out onto the covering, exposing the working conductor under the cable terminal from the insulation to ground together with the screen, bevelling the front of the exposed insulation to ground and mounting the multi-element cable head and the moulded cable terminal, wherein the tip of the power cable, cut to a suitable length and having an extruded insulation screen, is exposed by removing its protective covering at a length of at least a + f(Uo), (where (a) denotes the depth of the opening in the cable terminal in which to mount the cable working conductor, (f) is a voltage correction coefficient and has a constant value, and (Uo) is the cable phase voltage), the cable return conductor exposed by removing the protective covering is led out onto the remaining part of the protecting covering, the semiconducting screen that was mechanically extruded on the insulation is removed, specifically by peeling off at least one layer, from the exposed part of the cable to a length sufficient for the distance from the edge of the semiconducting screen that still remains on the cable to the front of the wires of the return conductors to be shorter than the length of the mounting lock in the body of the cable head, whereupon, using a special cable pencilling tool, the front of the basic insulation of the cable is bevelled at an acute angle to a length not shorter than 10% of the thickness of the insulation whereupon the exposed part of the cable and the point of bevelling are cleaned with an inorganic solvent and/or alcohol to remove any dirt and soil that may be present there, whereupon the cleaned surface is coated by spraying with a thin film of silicone oil or with another protective lubricant and then the resulting prepared cable insulation is coated with a film of silicone paste having a thickness of up to 0.1 mm to effectively fill up any microtraces having arisen while removing the extruded cable screen of which the edge is then coated with a strip of a special graphite-like paste based on a silicone binder, taking care to keep the strip at least as thick as the thickness of the screen while the width of the strip, depending on the length of the mounting lock built in the body of the head to be mounted on the cable, must be in the range from 25% to 30% of the length of the mounting lock and while the insulation area ahead of the edge of the cut-off conducting screen should be covered by at least one-half of the width of the strip and, right at that point, a suitable prefabricated cable head, selected from the appropriate set, is pulled mechanically onto the prepared cable terminal in such a manner that the body of the cable head is pulled mechanically onto the prepared cable using a special cable winch until the inside of the mounting flange of the cable head rests without a doubt on the front of the return conductor that was led out upon the cable covering while, as the body is being pulled, part of the extruded cable screen slides inside the mounting lock of the cable head, resulting in the mounting lock being filled tight with the graphite-type paste contained therein and of which the excess is collected in front of the screen edge with a special...