Good operation of power transformers is very important because they are among the most expensive equipment in the network generation, transmission and electricity distribution. It became necessary regular monitoring of such systems and determinate the life of a transformer, it preventing breakdown and corresponding loss occurrence.Ageing in the insulation system of power transformers is determinate by influence of air, moisture, temperature, mechanical and electrical stresses and insulation contamination. One of the most important ageing indicators in transformers is the water content in the solid part of the insulation. The water reduces drastically the dielectric strength of solid insulation, accelerate ageing in paper and can cause water vapor bubbles.In RVM method a voltmeter determines the recovery voltage (RV) after charging the insulation with a DC voltage. By subsequent relaxation and repeated charging for varied times the so called polarization spectrum can be created. RV range provides an indication on the condition in which there is the insulation of transformer. The paper analyzes measurements on two high power transformers in operation, determining the moisture content of solid insulation.
Determination of the geophysical model function of the ERS-1 scatterometer by the use of neural networks
