This paper deals with human exposure to extremely low frequency (ELF) electric fields generated by a transformer substation. The problem is twofold, i.e. it implies the assessment of the power substation electric field and the related current density induced inside the human body. The ELF electric field generated from a power substation is determined 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 in the vicinity of a substation the current density induced inside a simplified cylindrical model of the human body is obtained by solving the Pocklington integrodifferential equation using the Galerkin-Bubnov Indirect Boundary Element Method (GB-IBEM).

A procedure for the computation of the maximal value of extremely low frequency (ELF) magnetic fields from a power substation is proposed. The present technique is based on the multiquadric approximation of the magnetic field. The approximation is obtained using discrete field values calculated by the Biot-Savart law, where each energised substation conductor has been divided into a corresponding number of straight segments. The approximation sufficiently handles multidimensional multiextreme functions by interpolating their discrete values accurately. Subsequently, the maximal magnetic field value is evaluated by minimizing the negative multiquadric approximation via a stochastic optimization method -differential evolution. Therefore, the procedure provides the maximal field value assessment on the basis of the limited number of computed discrete values, thus reducing the computational cost.