| 摘要 |
PCT No. PCT/CH86/00102 Sec. 371 Date Mar. 18, 1988 Sec. 102(e) Date Mar. 18, 1988 PCT Filed Jul. 22, 1986 PCT Pub. No. WO88/00626 PCT Pub. Date Jan. 28, 1988.One of the bars of a contact bar, preferably the inner bar (12) has an electrical resistance which increases linearly along its entire length and which can be scanned as measurable value at any desired point along said bar. A preferable embodiment for this purpose is a metallic conductive spiral (11) which is wound onto a body of insulating material (10). An inner bar (12) configured in such a manner is held in an outer bar (13), the upper part of which is of U-shaped cross section, whereby a layer of insulating material (14) separates said inner bar from said outer bar of U-shaped cross section. The metallic conductive spiral (11) has, compared to a solid bar, a substantially higher electrical resistance which is suited for the purpose of method of measurements according to the principle of the electrical resistance bridge in order to localize a dropped drop wire on the contact bar in the event of a warp end breakage. The ratio of resistance determined from the electrical resistance bridge between the resistance of the total length of the inner bar (12) and the resistance of the partial length of the inner bar from one end of the bar to the dropped drop wire determines the distance from one end of the bar to the dropped drop wire.
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