Publisher's Synopsis
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1906 edition. Excerpt: ...they are opposed to the leakage currents, can slightly reduce the latter. According to Larsen's experiments it makes no difference with the corrosion effect whether the current flows steadily or intermittingly. And, therefore, there would be no appreciable reduction due to polarization. According to Lubberger, beside the stray currents in the Journal fur Gasbeleuchtung und Wasserversorgung, 1901, pp. 508 and 723. pipes there were currents of nearly a constant value which continued to flow after the cars had stopped running. While the cars are running the stray currents are superposed upon these constant currents, which Lubberger says are set up by the E.M.F.'s in the joints. Corrosion is caused by these constant currents independent of the leakage currents. Naturally the rails also become corroded and to a far greater extent than the pipes, since only a part of the stray currents enter the pipes. Therefore, if the rails are found to be badly corroded, it is positively known that there is considerable leakage. The danger zones for the pipes do not coincide with the places where the rails corrode, which statement follows from the formulas developed in the foregoing chapters. When rails which have lain near the middle joint (between the feeding points) for several years, show but slight traces of corrosion, it may be safely assumed that the pipes in that section are not exposed to danger from stray currents. The density of the current leaving the rails can be determined from formula (12). For a section of the length a at a distance x from the middle point the leakage current is exa _ IRa /L2 = 2Lr (3 X At the middle point (x = 0) with a = 1 meter and r the resistance of the leakage path per kilometer the current is IR 0.001 L 6r Any metallic...
