The present state of diagnostic tools, data transfer and processing allows to create automated system of continuous control of substation equipment based on thermal imagers, permanently installed such as surveillance cameras. There is at least three reasons why such online monitoring systems are used: increasing the reliability of the substation by providing timely identification of emerging defects, improving safety by preventing invasion and reducing costs of equipment condition monitoring. The effectiveness of these systems will be determined by an algorithm incorporated in the program to assess the state of substation objects for thermal images. At this research the technique of detection of of electrical equipment defects on the thermal images by identifying local, medium and RMS values of temperature anomalies at different substation objects. For each piece of equipment set the values of excess or excessive temperatures which is determining the degree of fault. For all substation objects in the generally results tabulated. The developed technique can be considered as the basis of technical specifications for program development for the automated thermal imaging system of electrical substation online monitoring in real time.