Abstract: According to dipole model, the electromagnetic filed distribution laws at the discharge instantly time are acquired. A calculation model and a numerical solution of electric and magnetic fields of indirect lightning over-voltage are proprosed. The influence laws of lightning current amplitude, cable length, cable height, termination resistor and lightning location on induced over-voltage are discovered: peak value of indirect lightning over-voltage is proportional to lightning current amplitude, cable length and cable height. But when the cable length is increased to a certain size, the peak value of indirect lightning over-voltage increase rate tends to be small; when the starting end is the match resistance, the indirect lightning over-voltage of ending increases with the increase of end resistance. The lightning location in the vertical direction of the cable on distance increasing, the indirect lightning over-voltage rapidly decreases, and does not become direct ratio with the distance, which provides the quantitative indicators to the lightning protection design of the military power supply.

Key words: electrical engineering, lightning-induced over-voltage, finite-difference time-domain, electromagnetic transient, power cable