This paper considers the effect of the discontinuity of electrolyte electrical conductivity on the distribution of potential and protective current density in cathodic protection systems with galvanic anodes. Its aim is to present a simultaneous application of both analytical and numerical models for the calculation of the distribution of protective potential and current density in the cases of homogeneous and double-layer electrolyte. For non-linear boundary conditions at the electrode surface (secondary distribution of protective current density), the indirect boundary element method is used, because of the complexity of calculation for which collocation at the point method was used. The calculation is further complicated due to the nonlinearity of boundary conditions at the electrode surfaces. In order to show the importance of this analysis, calculations for the observed system as well as of errors caused by neglecting the boundary discontinuity of the soil conductivity are provided. Based on these calculations and error analyses, the impact of the double-layer electrolyte on the correct calculation of the cathodic protection system with galvanic anodes is evaluated. This paper also provides the analysis when the double-layered nature of the electrolyte can be practically ignored, which is of great importance to designers of these systems.

Abstract Corona on transmission line conductors is a significant source of electromagnetic interference and corona loss. In order to analyze variable atmospheric condition on corona inception voltage gradient of bundle conductors a calculation model was established. The voltage gradient around stranded conductors for calculating corona inception voltage gradient is required. For the high voltage transmission lines, it is necessary to know the electric field in vicinity of the conductor's surface to determine the conditions for corona inception. The conditions under which corona discharge occurs for any arrangement of conductors are an important design consideration since corona can limit the performance of any given configuration of transmission line conductors. The AC corona inception voltage gradient criterion should involve the line characteristics, i.e., arrangement and size of conductors as well as atmospheric condition of the air in which the conductor is immersed. The numerical calculation method, as well as empirical equations, combined with gas discharge theory is adopted to investigate corona inception voltage gradient. The electrical field enhancement at the tip of each strand is about 14% higher than the electrical field for a cylindrical conductor of the same overall diameter. According to self-sustained corona discharge criterion in a severe non-uniform electric field, variations of pressure, temperature and humidity on corona inception voltage gradient of bundle conductors are analyzed. Increased voltages in 400 kV electric power network of Bosnia and Herzegovina causes increase the value of voltage gradient and higher power losses due to AC corona. Therefore, it is important to determine the value of the voltage gradient in vicinity of conductor's surface as well as corona inception voltage gradient to accurate determined power losses due to AC corona.

Sažetak Proračun otpora rasprostiranja složenih uzemljivača visokonaponskih transformatorskih stanica, te definiranje raspodjele potencijala na površini tla predstavlja jednu od najsloženijih faza izrade projektne dokumentacije. Ovi proračuni se izvode u cilju određivanja vrijednosti napona koraka i dodira na cijeloj površini lokacije transformatorske stanice. U ovom radu predstavljen je numerički algoritam za proračun parametara uzemljivača. Uz pomoć softverskog paketa Matlab izvršen je proračun otpora rasprostiranja i raspodjele potencijala uzemljivača transformatorske stanice 10(20)/0.4 kV.