Osama Gouda

Abstract—Power and distribution transformers reliability is limited by the electrical insulation system quality, which also operates additionally as a heat transfer medium. On the other

Abstract: Arc interruption of high voltage direct current (HVDC) circuit breakers (CBs) is one of the main challenging factors for using HVDC grids. To evaluate the arc interrupting capability in HVDC CBs, black box arc models are used to represent the nonlinear arc conductance depending on Cassie and Mayr dynamic arc equations. Extensive simulation studies are carried out to investigate the effect of controlled and uncontrolled parameters on the CB arcing time.

Recently, polymers Nano-Composites for various important electrical apparatus are widely used. This paper studies the dielectric properties of high density polyethylene composed with different concentrations of clay-Nano-filler over a high frequency range of 200 to 2 MHz. This paper studies also the frequency and temperature dependence of relative permittivity (er) and loss tangent (tan delta) of pure high density polyethylene and polymer composites with clay-Nano-filler of different concentrations over high frequency range of 200 Hz to 2 MHz and a temperature range of 0–50
C.

Abstract: One of the common causes of cross-linked polyethylene (XLPE) insulation ageing and finally cable failure is the
presence of a cavity within cable insulation. Gas filled cavities can be initiated in XLPE cables during its manufacturing,
installing and operating conditions. Once the size of the cavity reaches the critical limit, noticeable partial discharge (PD) activity
develops. Therefore, the size of the cavity is one of the important factors that considered when investigating the PD activity in

Abstract: Dissolved gas analysis (DGA) is one of the most acceptable methods used for detecting and evaluating gases
dissolved in mineral oil and also in the solid insulation of internal incipient faults in the power and distribution transformers based
on the oil samples. DGA has been proved the most accurate method for condition assessment of power and distribution
transformers. The fault types depend upon type and concentrations of each gas dissolved in oil. IEC, Rogers, Doernenburg and

Abstract: This study investigates the impact of electrical parameter variation of a high-frequency transformer model on its
sweep frequency response analysis (SFRA) signature to help in classification and interpretation. The simulations have
been done using MATLAB and compared with the reference data. The results of SFRA measurements are repeatable
up to and beyond 1MHz. The proposed diagnostic methodology using the Cross-Correlation Coefficient Factor (CCF) is
used to identify the transformer faults. CCF used to measure the degree of relationship between two variables that