Investigation of transformer oil breakdown using optical fiber as sensor

Breakdown of transformer oil plays a critical part in the operation of a transformer. Early detection of the breakdown in transformer oil can prevent the catastrophic losses of the transformer. It has been reported that there is no suitable online monitoring system to investigate breakdown in transformer oil. This paper presents an optical sensor based transformer oil insulation breakdown monitoring system using sphere-sphere 2.5 mm electrodes in the test cell in accordance with IEC 156 standard. It investigates the change of internal characteristics of transformer oil in terms of light output as voltage due to the breakdown in the oil. An ultraviolet visual spectrophotometer is employed to examine the changes in the oil samples. The result of the experiment shows that the breakdown has the significant effect on transformer oil. It is concluded that the breakdown in the insulating oil changes its properties that reflect on the proposed sensor output voltage indicating the occurrence of breakdown in the insulating oil.