To provide reliable power supply to ladle-furnace units in the electric steelmaking workshop of the metallurgical plant, continuous monitoring of the technical condition of the high-voltage equipment of closed switchgears is advisable. The authors propose a solution developed for solving a complex task of equipping electrical devices with on-line monitoring systems. The commercialization of such a system on bushings at closed switchgears 110 kV is being considered. Bushings are characterized, and the importance of their fault-free operation is stressed. The substantiation is given for the methods of condition monitoring, based on a set of diagnostic parameters, which (methods) should be implemented in the system being built. The functions of the control and measuring equipment are listed, the main ones are the following: calculation of the bushing electrical parameters and the characteristics of the unbalance of conduction currents, as well as calculation of the parameters of partial discharges (PD) in the insulation. The scheme of the developed system is provided, the choice of equipment is justified. The system includes a TIM-3 processor unit and complex DB-2 sensors manufactured by DIMRUS. The characteristics of the software to display necessary diagnostic information is given. The main window of the user interface is considered, the form of displaying PD characteristics is presented. According to their average values, the condition of the equipment satisfying the “Norm” criterion was diagnosed.