IEC 60426:2007 pdf free download

IEC 60426:2007 pdf free download Electrical insulating materials – Determination of electrolytic corrosion caused by insulating materials – Test methods
1 Scope
This standard determines the ability of insulating materials to produce electrolytic corrosion on metals being in contact with them under the influence of electric stress, high humidity and elevated temperature. The effect of electrolytic corrosion is assessed in one test by using consecutively two methods:
• visual semi-quantitative method consisting in comparing visually the corrosion appearing on the anode and cathode metal strips, with those given in the reference figures. This method consists of the direct visual assessment of the degree of corrosion of two copper strips, acting as anode and cathode respectively, placed in contact with the tested insulating material under a d.c. potential difference at specified environmental conditions. The degree of corrosion is assessed by visually comparing the corrosion marks on the anode and cathode metal strips with those shown in the reference figures;
• quantitative method, which involves the tensile strength measurement, carried out on the same anode and cathode metal strips after visual inspection. An additional quantitative test method for determining electrolytic corrosion, which involves tensile strength measurement of copper wire, is described in the informative Annex C.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
IEC 60068-3-4:2001 , Environmental testing – Part 3-4: Supporting documentation and guidance – Damp heat tests
IEC 60454-2:⎯, Pressure-sensitive adhesive tapes for electrical purposes – Part 2: Methods of test 1
3 Terms and definitions
For the purposes of this document the following terms and definitions apply.
3.1
electrolytic corrosion
kind of galvanic corrosion caused by joint action of external source of d.c. potential and some substances included in some organic materials in presence of high humidity and elevated temperature
3.2
test strip
a) positive
a metal strip connected with positive pole of direct current source which forms the anode in the contact system: metal – insulating material
b) negative
a metal strip connected with negative pole of direct current source which forms the cathode in the contact system: metal – insulating material
3.3
surface of contact
a) of tested material
part of insulating material specimen which is in direct contact with metal strips
b) of metal strip
part of metal strip (positive or negative) which is in direct contact with insulating material specimen
4 General description of the test method
The test consists of applying specified environmental conditions and a d.c. potential difference to two parallel copper strips 3 mm apart, acting as the anode and the cathode respectively. The insulating material under test (test specimen) is placed across these two strips. In order to obtain a good and uniform contact between the metal strips and the material under test, the test specimen is pressed to the strips by a cylindrical loading tube.