Dissolved gases analysis of rice bran oil under thermal fault for transformer application

Dissolved gas analysis (DGA) of transformers can reveal electrical stresses encountered by oil-immersed power
transformers. DGA can potentially avoid additional damage
since it identifies incipient transformer failures. In this paper, a comparison of DGA under electrical breakdown between conventional transformer oil; Mineral Oil (MO) and Rice Bran Oil (RBO) has been discussed. The many approaches developed for analyzing these gases and interpreting their significance include Key Gas, Duval Triangle and Pentagon Method, Doernenburg Ratio, Rogers Ratio, and IEC Ratio. Based on the results, the diagnostic approaches were not completely reliable for identifying electrical faults in RBO. The findings suggest that present DGA interpretation procedures for RBO or vegetable oil shall be properly modified. In the case of MO, however, DGA analysis indicated that there is a thermal crack in the oil sample that must be addressed. Once the fault has been determined, test instruments are needed to help narrow the fault area and identify the problem component.