The behavior of three phase five leg transformer under voltage sag is studied in this paper. This paper proposes a simple, practical model of a three phase-five leg, saturated transformer with accurate performance. Transformer saturation is produced when the voltage sag is recovered and it causes inrush current in transformer. Effects of voltage sag depth, duration and initial point on wave hav...

High-voltage transformers are among the most important elements in an electric-power system. Each one of them is affected by various external factors: overvoltage, partial discharge (PD), overheating, vibrations, etc., which created a strong electric field, thermal effect, humidity, impurities, factory defects, dissolved water and gas oil-type-transformer insulation. These other factors, caused...

Transformer inrush currents are highmagnitude, harmonic-rich currents generated when transformer cores are driven into saturation during energization. These currents have undesirable effects, including potential damage or loss-of-life to the transformer, protective relay misoperation, and reduced power quality on the system. Controlled transformer switching can potentially eliminate these trans...

The multi-winding medium frequency transformer (MMFT) has attracted widespread attention, since its application in power electronic transformers can simplify the system structure and reduce volume weight. However, special working conditions of MMFT due to high voltage density increase difficulty insulation design for MMFT. For this issue, paper presents a comprehensive analysis electric filed c...

he presence of moisture in a transformer deteriorates transformer insulation by decreasing both the electrical and mechanical strength. In general, the mechanical life of the insulation is reduced by half for each doubling in water content [l]; the rate of thermal deterioration of the paper is proportional to its water content [2]. Electrical discharges can occur in a high voltage region due to...

In recent years, the new type design of current transformer with bushing structure has been widely used in distribution network system due to its advantages miniaturization, high mechanical strength, maintenance-free, safety and environmental protection. The internal temperature field is an important characteristic parameter characterize thermal insulation aging performance transformer, mainly ...