Operating the electrical power systems at normal conditions is our goal always. This is what represents the ideal state of electrical power system work. Hence, the electrical power system work in case of insufficient electrical power requires avoiding since it leads to big losses in national economy. These losses could be huge when we talk about connection borders between systems as per overload frame, because of lack of electrical power request. The impact of these conditions could be noticeably decreased at a reasonable limit of electrical power request. When we find out the optimal solution of electrical power systems operation and the communication lines between them while considering the losses of consumers disconnecting that guarantee the stability of loads. Finally, it is so at full use of maneuver (available cases) spare power properties when applying the instant correction of regime. This paper studies the basic approach to solve these issues which imply the reliability definitions.