Experimental research on gassing characteristics of transformer oils under low thermal decomposition

The gas production of transformer oil A (Shell Diala BG) and transformer oil B (NYNAS 10XN) under normal operating temperature (70–140C) were tested by dissolved gas analysis (DGA). By analyzing the influence of different heating time and different temperature on gas production and gassing rate, the similarities and differences of gassing characteristics of transformer oil A and transformer oil B were summarized. Distillation range and hydrocarbon composition were detected to analyze the reasons for these differences of gassing characteristics. The results showed that chemical composition leads to the differences in thermal stability between transformers oil A and transformers oil B. Then the difference of gassing characteristics between transformer oil A and transformer oil B at 70–140C was obvious.