In practice, often there is a need for modeling systems for canceling the Earth electrostatic field. For this purpose, a linear circular loop can be used. The realized protection is as better as the used ring is thicker. In practical applications, a system of coaxial linear loops is used instead of one thick ring. In order to find the influence of protected object shape and volume to the electrostatic protection efficiency, a protected object is modeled as a half spherical electrode, placed with its flat side on the ground. According to the theoretical analysis, a general numerical program has been developed and numerical results are shown graphically. .