In atmospheric surge protection level calculations of high voltage transmission lines, is necessary to define the conditions of lightning current amplitudes distribution, taking to account equivalent resistivity of objects (line conductor, shielding wire or line tower). In case, when lightning discharge happens in phase conductors or bad grounded shielding wire, the lightning current amplitudes is much more lower, then in qualitative grounding cases. The methods of transmission lines components modeling in ATP-EMTP program, is the most important to determine lightning currents with zero initial derivative. When calculation purpose is protection devices instalation distance definition in substations and steep front waves propagation in overhead line is ascertained, lightning current impulse with zero initial derivative application is reasonable too. By the example of lightning discharge currents parameters decision, the article renders the application of the ATP-EMTP program system. The program set enables mastering the skills of operation in this environment in the shortest possible time.