| 摘要 |
PCT No. PCT/SE94/00793 Sec. 371 Date Mar. 1, 1995 Sec. 102(e) Date Mar. 1, 1995 PCT Filed Aug. 29, 1994 PCT Pub. No. WO95/06761 PCT Pub. Date Mar. 9, 1995In a metallic pipeline (1) disposed in the ground, alternating voltages may be induced from adjacent transmission lines and cause corrosion. To reduce the risk of corrosion, an alternating current (i1) is caused by means of a compensating device (PD) to flow through the line and to cause a voltage drop which counteracts the induced voltages. A measuring conductor (2) provides a signal (us) which is a measure of the induced voltage. This signal controls the amplitude and phase position of an alternating voltage (u1) which is generated by an a.c. source which is connected to feed points (A, B) on the line and which causes an alternating current (i1)) to flow through the line. (FIG. 1a)
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