Definition of the minimal sparkover voltage of long air gaps

In work results of calculation of the minimal sparkover voltage and definitions of parameters of discharge process in long air gaps are resulted at positive polarity of a pulse. The new model of inception and steady development of the positive leader in a long air gap is offered. The model is based on the approach of a determining role during steady development of the leader in a gap polarizing and free charges of a cover of the channel of the leader. The theoretical dependence connecting parameters of discharge process at propagation of the positive leader with parameters of a pulse of a voltage, put to a gap is received. On the basis of this dependence the new formula for calculation of the minimal sparkover voltage in a long air gap a rod - a plane is received. Calculations of such voltage for gaps in a range from 0.2 m till lengths of gaps, characteristic for the discharge of a natural lightning are resulted. Results of calculation are in the good consent with available experimental data. The conclusion about limiting electric strength of super-long air gaps and possible potential of a storm cloud is made.