Sabau, John; Fofana, Issouf; Gal, Stelian; Oltean, Marius
TRANSELECTRICA; SMART
Currently, none of the existing procedures aimed at avoiding the oxidation of liquid insulation in power transformers is capable of completely eliminating this century old deficiency. Consequently, the solid insulation is deteriorated ahead of time. Now, more accurate test methods developed by ASTM allow the determination of oxidation decay products as trace impurities. These suggest that the colloidal sludge is a contributing factor to the formation of incipient electrical failures that trigger the gassing of oil, diagnosed based upon the interpretation of DGA. In this contribution, the outcome of an industrial experiment designed to demonstrate a new nitrogen blanketing system is presented. The technical solution involved purging of the oil surface in the conservator by a constant flow of pure nitrogen. Analysis performed over an 8 years period; clearly indicate that this innovative, environmentally friendly, and economically affordable technique can arrest/reduce the oxidation decay process of oil-paper insulation in free breathing power transformers.
