Satoru Toyama

Hydrogen generation by adding passivator for suppressing copper-sulfide deposition in transformers

Generation of hydrogen from oils with the addition of passivators such as 1, 2, 3-benzotriazole (BTA) and Irgamet® 39 for suppressing copper sulfide deposition was investigated by heating tests. Large amounts of hydrogen were generated from the oils with the addition of Irgamet® 39 compared to the oils with the addition of BTA. BTA is suitable in terms of less generation of hydrogen. For Irgamet® 39 added oils, the amounts of hydrogen increase with an increase in oxygen concentration. Irgamet® 39 was consumed by thermal decomposition and oxidation. Consumption by oxidation of Irgamet® 39 is considered to be affected to the hydrogen generation. Amounts of hydrogen increase with increase in heating temperature for a certain period of time. After conducting heating test, Irgamet® 39 was remained in oil. Total amount of hydrogen, which is defined by sum of the amount of hydrogen generated by consumed Irgamet® 39 and the amount of hydrogen generated by residual Irgamet® 39, are considered to be independent of heating temperature. Effects of additives such as dibenzyl disulfide, which is one of the prime compounds that cause the copper sulfide deposition, and 2, 6 ditertiary-butyl paracresol as antioxidant on hydrogen generation were significant. Consequently, in case of adding Irgamet® 39 for the purpose of suppressing copper sulfide deposition, installation of a conservator system and rubber bag which reduces the dissolution of oxygen into the oil is effective to minimize the amount of hydrogen.