Evaluation of effectiveness and safety of CO2 cleaning of energized contaminated pad-mounted gear

This paper provides an overview of how CO2 cleaning works on energized electrical equipment. Contaminants can significantly reduce the dielectric strength of insulating materials in the electric equipment. These contaminants can cause increased levels of leakage current to pass over dielectric materials, leading to electrical breakdown due to surface tracking. Such conditions can result in flashovers, which can damage electrical equipment and cause unplanned service outages, as well as safety concerns. Experimental procedure to test the effectiveness of CO2 cleaning in reducing leakage currents due to contamination is discussed. The CO2 cleaning test results show that the cleaning process can be efficient and safe in cleaning exposed insulating surfaces. The analysis of leakage currents, measured during the cleaning process, indicate that there is a significant number of short duration discharges of leakage current. The number of discharges is reduced significantly as the magnitude of the leakage current increased. The leakage current observed during the process was measured in milliampereres during the short duration discharges, and never exceeded 34mA.