Detection of Total Corrosive Sulfur in Transformer Oil

The quantitative analysis methods of the total corrosive sulfur (TCS) in transformer oils were realized using copper powder corroding technique. In this technique, excess copper powder reacted with insulating oils at 150°C for 12 hours to form corrosion product (CU2S). Then, Cu2S was oxidized to CuSO42−, and finally dissolved to sulfate solution. There are three methods to test the amount of TCS. SO42− solution tested by ion chromatography (IC) or Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES). Moreover, adopted ICP to test total sulfur (TS) in oils before and after corrosion reaction, and the difference value is the content of TCS. Comparing with these methods, it was found that ICP detection of total sulfur (TS) in oils could achieve excellent linearity. The correlation coefficients is R2≥0.999, and the recovery rate is 98.4%∼103.4%.