Of high-pressured end make, the stuff that I believe to each report are repaired has not been familiar with again, the structure that the article explains high-pressured cable from theoretic labor and make craft demand actually, I consider as a good literary works to recommend everybody under the counter.
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About 3 problems of insulation
1, can see from inside the structure of cross-linking polyethylene cable, in cable advocate the semiconductor outside there is outside insulation layer and cupreous screen, if cable is medium,the layer mixes this semiconductor outside the layer cupreous screen is nonexistent, can insulation puncture happen between the core in 3 core cable and core so?
2, there is a paragraph of small cable necessarily in head of terminal of 3 core cable outside layer of screen of semiconductor and copper is divested, so is paragraphs of are this small cable weak point?
3, whether is through paring less except semiconductor mixed cupreous screen layer (withhold as far as possible longer outside layer of screen of semiconductor and copper) will method overcome this problem? Is reservation longer outside what disadvantage does layer of screen of semiconductor and copper have?
What go up in cable structure is alleged " screen " , it is a kind of measure that improves electric field to distributing essentially. Cable conductor is wrung by much root lead close and become, between it and insulation layer easy form air gap, conductor surface is not slick, can cause electric field concentration. The screen layer of a half conductor is added in conductor surface, it and by the conductor of screen equipotential as good as insulation layer contact, avoid to produce partial discharge between conductor and insulation layer thereby, this one screen is inside screen layer; Be in in insulation surface and jacket contact likewise put possibly also in clearance, it is the element that causes partial discharge, reason adds the screen layer of a half conductor in insulation layer surface, it and be had by the insulation layer of screen good contact, as equipotential as metallic sheath, avoid to produce partial discharge between insulation layer and jacket thereby, this one screen is outside screen layer; Without the insulated cable pushing a package of metallic sheath, outside removing layer of half electric screen, increase the belt that use copper or cupreous silk to bypass the metallic screen layer of the bag even, the action of layer of this metal screen, capacitance electricity is carried when moving normally; When the system short-circuits, as the passageway of short-circuit current, also have the effect of screen electric field at the same time. Visible, if cable is medium,the layer mixes this semiconductor outside the layer cupreous screen is nonexistent, the possibility that insulation puncture produces between the core in 3 core cable and core is very large.
Divest when terminal of the cable that make or connect layer of a paragraph of small screen is main the purpose is to be used make sure high pressure is right of the distance climbing report of the ground, this screen fracture surface manages stress very concentration, it is weak point! Must adopt proper measure to undertake stress is handled. (wait with stress awl or stress canal)
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