A new mathematical model of the hardware-redundant technical system has been developed, containing the main functional and redundant units, for their plug-in instead of the failed main ones, in a conflict situation. In the proposed model, besides the restrictions associated with the replacement of the failed units, the backup only in the group, to which they relate, has further restrictions, reflecting the real working conditions and organizational and structural principles of the technical systems associated with the external backup units intended to replace the failed the main functional units in the corresponding group of the units in the process of a conflict. The aim of these restrictions is to ensure that the reasons to connect the redundant power in the relevant group are not less than certain constructive and technical features of the system, the number of the main units arranged in a row, failed in the process of a conflict in this group. The model also takes into account the reliability of the system of the final control over the technical system and connection of the redundant power instead of the failed one during a conflict. Due to its behavior involved in a conflict situation, the technical system is described by a system of differential equations with the variable in time coefficients, while the study of this system by analytical methods is not possible. Therefore, in this paper the authors propose a method of approximate calculation of the average lifetime of a technical system involved in a conflict, allowing numerical methods to determine the optimal structure parameters of the technical system, which ensures maximization of its average lifetime in the process of a conflict.