Most vegetable oils with suitable viscosity and pour point to be used in natural ester dielectric fluid contains mainly unsaturated fatty acid including oleic (one C=C double bond), linoleic (two C=C double bonds) and linolenic (three C=C double bonds). Soybean oil was chosen among 40 candidate blends of vegetable oils during the development of FR3® Fluid.

Nowadays, partial discharge (PD) measurement is one of the most reliable methods to evaluate the insulation conditions of HV apparatus on local problems. The insulation is the key point of the equipment lifetime. 

Defect in insulation due to manufacture, assemble or ageing are evidenced by PD generation that accelerates the degradation process causing premature dielectric failure. 

A 200MVA, 500/200kV Transformer was detected and indicated that there are 88 Liters  of water inside the transformer and the 87.6 Liters was inside the paper