1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 , TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITUCONSTRUCTION, INSTALLATIONAND PROTECTION OF CABLE AND OTHERELEMENTS OF OUTSIDE PLANT#/22/3)/.G0G0#!53%$G0G0“9G0G0!,4%2.!4).#522%.4)45G134G0G0RecommendationG0G0, (Extract from the “LUEG0“OOK)NOTES1 ITU-T Recom
2、mendation L.8 was published in Volume IX of the Blue Book. This file is an extract from theBlue Book. While the presentation and layout of the text might be slightly different from the Blue Book version, thecontents of the file are identical to the Blue Book version and copyright conditions remain u
3、nchanged (see below).2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both atelecommunication administration and a recognized operating agency. ITU 1988, 1993All rights reserved. No part of this publication may be reproduced or utilized in any form or by
4、any means, electronic ormechanical, including photocopying and microfilm, without permission in writing from the ITU.Volume IX - Rec. L.8 1Recommendation L.8Volume IX - Rec. L.8CORROSION CAUSED BY ALTERNATING CURRENT(Geneva, 1976)Laboratory experiments and the results of examinations of industrial i
5、nstallations show that stray alternatingcurrents can cause corrosion.However, other experiments on lead to compare the effects of direct current and alternating current by weightloss show that the corrosion effect due to a.c. is very slight compared with corrosion by d.c. A.c. corrosion appears inth
6、e form of pitting.The following points should nevertheless be noted: the corrosion, although rare, occurs more readily with frequencies below the usual mains frequency of50 Hz or 60 Hz; rectification may occur due to the nature of the soil or to the presence at the surface of the metals of oxidesor
7、polluting substances.There is no practical way of finding out the current densities and the voltages at which corrosion occurs. Theindividual pitting that is usual, the fact that anodic and cathodic reactions occur on the same surface of the metals, andvariations in the chemical characteristics of the environment make it impossible for any accurate concept or definitionof critical current density to be worked out at present.It seems reasonable to suggest that a.c. at low voltage is not usually harmful to steel or lead but may corrodealuminium in some cases.
