The article considers the features of the occurrence of violations in the high-voltage electrical network, as well as the thermal imaging control of capacitors and high-frequency traps, the number of monitored points of this electrical equipment, the diagnostics of 35 kV capacitors of the “ladle furnace” installation of converter shops with a description of the transient process in the event of a defect, battery elements, as well as design features of capacitors and high-frequency traps with voltage 110...220 kV, the tangent of dielectric loss angle tgδ, the values of active current and steady-state voltage were calculated, the results are summarized in the table. Based on the calculations, a method of thermal imaging control was formed with the considered terms for eliminating these defects; a conclusion about the need to control the elements of the power supply system was made.