Field Distribution In Transformer Research Articles

Electric Field Simulations and Analysis for High Voltage High Power Medium Frequency Transformer

The electronic power transformer (EPT) raises concerns for its notable size and volume reduction compared with traditional line frequency transformers. Medium frequency transformers (MFTs) are important components in high voltage and high power energy conversion systems such as EPTs. High voltage and high power make the reliable insulation design of MFT more difficult. In this paper, the influence of wire type and interleaved winding structure on the electric field distribution of MFT is discussed in detail. The electric field distributions for six kinds of typical non-interleaved windings with different wire types are researched using a 2-D finite element method (FEM). The electric field distributions for one non-interleaved winding and two interleaved windings are also studied using 2-D FEM. Furthermore, the maximum electric field intensities are obtained and compared. The results show that, in this case study, compared with foil conductor, smaller maximum electric field intensity can be achieved using litz wire in secondary winding. Besides, interleaving can increase the maximum electric field intensity when insulation distance is constant. The proposed method of studying the electric field distribution and analysis results are expected to make a contribution to the improvement of electric field distribution in transformers.

光学的電界測定による変圧器油/プレスボード複合系電界分布の温度特性に対する検討

光学的電界測定による変圧器油/プレスボード複合系電界分布の温度特性に対する検討

Electric field in transformer oil measured with the Kerr-effect technique

The electric field distribution in transformer insulating oil was measured as a function of time, both after application of a DC step voltage and after polarity change of the DC voltage, using a highly sensitive advanced Kerr electro-optic technique. The lower limit of the applied electric field intensity was 100 V/cm in insulating oil with an electrode length of 8 cm. Charge distribution as a function of time was calculated from the measured electric field distribution. The mobility of ionic carriers, 2.1*10/sup -5/ cm/sup 2//Vs, in paraffinic transformer oil was obtained from the relationship between the saturation time of charge density and the applied DC voltage. The relaxation time of accumulated charge near the electrodes after short-circuiting the electrodes was independent of the pre-applied DC voltage. >