Nikša Kovač

The assessment of human exposure to low frequency and high frequency electromagnetic fields using the boundary element analysis

Abstract Analysis of the human body exposed to low frequency and high frequency electromagnetic fields is presented in this work. The formulation of the problem is based on a simplified thick wire model of the human body. The current distribution induced in the body is determined by solving the Pocklington integral equation for a straight thick wire via the Galerkin–Bubnov boundary element method. Once the axial current along the equivalent antenna of the body is obtained, one may calculate the induced current density, electric field, specific absorption rate, and the total absorbed power in the human body. Several realistic exposure examples are given.

An Improved Formula for External Thermal Resistance of Three Buried Single-Core Metal-Sheathed Touching Cables in Flat Formation

An improved formula for the assessment of the external thermal resistance of three buried single-core, metal-sheathed, touching cables, laid in a flat formation, is proposed. The formula arises from the analysis based on a coupled electric-thermal model, as well as on the stochastic optimization method based on differential evolution. The effect of the new formula on cable rating is illustrated in a numerical example.

Computation of maximal electric field value generated by a power substation

A procedure for a computation of the maximal value of extremely low frequency electric field from a power substation is presented.

Transient Analysis of a Finite Length Line Embedded in a Dielectric Half-Space using a Simplified Reflection/Transmission Coefficient Approach

The paper deals with a transient analysis of a finite length wire embedded in a dielectric half-space and illuminated by the electromagnetic pulse (EMP) using a simplified reflection coefficient approach. A direct time domain formulation is based on the wire antenna theory and on the corresponding Hallen integral equation for half-space problems. The presence of a dielectric half-space is taken into account via the simplified reflection/transmission coefficient arising from the modified image theory. The Hallen equation is solved via the time-domain Galerkin-Bubnov scheme of the Indirect Boundary Element Method (GB-IBEM) and some illustrative numerical results are presented. The transient response obtained using the simplified reflection/transmission coefficient approach is compared to the results obtained via the Fresnel coefficients approach.

Sheath Loss Factors Taking Into Account the Proximity Effect for a Cable Line in a Touching Flat Formation

This paper presents the development of a correction coefficient for the International Electrotechnical Commission (IEC) Standard 60287-1-1 formula for the sheath loss factor of the middle cable in a touching flat formation. The solid sheaths are bonded and earthed at both ends of an electrical section. The reason for this correction is to take into account a nonuniform distribution of the losses within each sheath arising from the proximity effect. The coefficient is developed by using the filament method as well as the stochastic optimization algorithm based on differential evolution. The IEC formulae for the sheath loss factors of the outer cables, forming a part of the touching formation, do not need to be modified in order to consider the proximity effect.

Assessment of Human Exposure to Power Substation Electric Field

The paper deals with human exposure to extremely low frequency (ELF) electric fields generated by transformer substation. The problem is twofold, i.e. it requires the calculation of power substation electric field and current density induced inside the human body. ELF electric field generated from a power substation is assessed by solving the Scalar Potential Integral Equation (SPIE) using the Source Element Method (SEM), a variant of the Indirect Boundary Element Method (IBEM). Knowing the electric field due to the substation the current density induced within the human being exposed to such field is obtained by solving the Laplace equation variant of the continuity equation using the direct Boundary Element Method with domain decomposition (BEM-DM). Some illustrative computational results for external electric field and internal current density are presented.