Electrical insulating materials at high atmospheric humidity and under the influence of electric stress may cause corrosion of metal parts in contact with them. Such electrolytic corrosion is dependent upon the composition of the insulating material and the character of the metal; it is influenced by temperature, relative humidity, nature of the voltage and time of exposure. Direct voltage produces much more rapid and extensive corrosion than alternating voltage. Corrosion is more pronounced at the positive electrode.
Not only copper but also most other metals, except the noble metals such as platinum, are subject to electrolytic corrosion. Electrolytic corrosion, however, is usually determined with insulating materials in contact with copper or brass. Other metals may be used when needed for special purposes, but the results may differ from those described in these methods.
This recommendation includes:
1) A visual semi-quantitative method for determining electrolytic corrosion.
2) A quantitative method for determining electrolytic corrosion which involves tensile strength measurements of copper wire.
3) An indirect method using a quantitative measurement of insulation resistance.
SIS SS IEC 426:1982 history
1982SIS SS IEC 426:1982 Test methods for determining electrolytic corrosion with insulating materials