The TOR-5 system continuously monitors and controls the condition of power transformers, including special-purpose types such as traction, mining, marine, and wind turbine step-up transformers, by assessing the state of their insulating oil and insulation. The system measures key parameters such as water content in the oil and solid insulation, dielectric strength, and oil quality index. It connects directly to the transformer, creating a closed-loop circulation where oil is drawn from the bottom of the tank, passes through sensors, and returns to the top. Measurements are taken once per minute and transmitted to a cloud server, where additional calculations provide a comprehensive evaluation of the transformer’s condition.