Distribution of the geomagnetically induced currents between the neutrals of certain power transformers in the standard configuration power grids is investigated. The allowances at which the quantitative estimates of the geomagnetically induced currents are obtained are formulated. A spatial model that allows considering a geographical arrangement of the power transformers when calculating the geomagnetically induced currents is offered. The paper suggests that the concept of a relative power grid electric length can be used as a quantitative criterion for grid vulnerability to the impact of the geomagnetically induced currents. The conditions under which the most powerful power transformer of a radial power grid is not exposed to the geomagnetically induced currents are defined. The quality assessment for the main configuration power grid vulnerability to the impact of the geomagnetically induced currents is given. The features of a spatial model of the power grid with the ring configuration, defining the vulnerability degree to the geoinduced currents impact, are considered. It is shown that the power transformers are exposed to the heaviest impact of the geomagnetically induced currents in the power grids of the ring configuration, all other conditions being equal.