SYMPOSIA PAPER Published: 01 January 1956

Catalysts for Accelerated Aging Testing of Transformer Oil


A number of experimental and normal transformer oils have been tested for accelerated aging. The main features of the test method are in agreement with ASTM Method of Test D 1314, but, in order that the supply of oxygen should not be a governing factor in the oxidation process, oxygen was bubbled through the oil at a sufficient rate, usually 1 liter per hr. The temperature has been varied, though the bulk of the experiments have been carried out at 100 C. Both solid and soluble metal catalysts have been studied. When solid copper is used as a catalyst, two things take place. One is a dissolution of copper in the oil; the other consists of oxidation of the oil, catalytically influenced by the dissolved copper. The dissolution of the metal takes place mainly at the beginning of the oxidation, the extent of this “corrosion” depending partly on the properties of the solid metal and its area and partly on the type of oil. The oxidation is governed by the type and concentration of the catalyst and is, furthermore, dependent on the type of oil. The copper is soon again precipitated as sludge and only small amounts remain in solution—about the same magnitude, 0.05 to 0.2 ppm, as will be found in transformer oils in service. The advantage of employing soluble catalysts are discussed, and it is shown that inhibited as well as uninhibited oils may be readily evaluated with the aid of soluble catalysts. A mixture of copper and iron naphthenates is recommended for practical use.

Author Information

Liander, Halyard
Asea, Västerås, Sweden
Ericson, Gosta
Asea, Västerås, Sweden
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Developed by Committee: D09
Pages: 1–23
DOI: 10.1520/STP48020S
ISBN-EB: 978-0-8031-8374-2
ISBN-13: 978-0-8031-6862-6