IEC 62535 Insulating liquids - Test method for detection of potentially corrosive sulphur in used and unused insulating oil
6.4 Result
If, for both of the duplicate samples, a positive result is found for copper, or paper, or both, the oil shall be reported as potentially corrosive. If, for both samples, a negative result is obtained for both copper and paper, the oil shall be reported as non-corrosive.
If the results for the duplicate sample are different, the test shall be repeated.
NOTE If there are any doubts in the interpretation of the results of inspection of paper, the composition of precipitate should be analysed by other methods (for example by SEM-EDX). If the precipitate is identified as copper sulphide, the oil must be reported as potentially corrosive.
7 Repeatability and reproducibility
Repeatability: according to inter-laboratory tests carried out by CIGRE WG A2.32, duplicate results had 100 % agreement.
Reproducibility: according to inter-laboratory tests carried out by CIGRE WG A2.32, 2 laboratories out of 16 had different results. In these cases the oils differed from the original delivered batches.
8 Report
The test report shall contain at least the following information:
testing laboratory;
the type and identification of the product tested;
a reference to this International Standard;
the result of the test (see 6.4);
any deviation, by agreement or otherwise, from the procedure specified;
the date of the test.
