EN transformer bushings are critical insulating components for European standard oil-immersed transformers, operating continuously in outdoor substations, industrial sites, residential distribution areas, and new energy power stations. During long-term operation, the outer surface of porcelain and epoxy resin EN transformer bushings inevitably accumulates various pollutants, including floating dust, industrial particles, salt fog crystallization, bird droppings, and corrosive sediment. Severe surface pollution is one of the leading causes of common bushing faults, such as reduced creepage distance, surface leakage current, partial flashover, and accelerated insulation aging. Mastering scientific and standardized surface cleaning methods for polluted EN transformer bushings is essential to restore insulation performance, eliminate hidden operational risks, and extend the service life of power transformer equipment.
Unlike general industrial component cleaning, EN transformer bushing cleaning requires strict compliance with electrical safety specifications and material protection standards. Improper cleaning tools, unqualified cleaning agents, or irregular operation processes may scratch the insulating surface, damage hydrophobic coatings, corrode sealing structures, or even trigger electric shock and flashover accidents. This article systematically introduces classification of bushing pollution, applicable cleaning scenarios, standardized surface cleaning methods, and key safety best practices for polluted EN transformer bushings, providing professional guidance for power operation and maintenance teams.
Common Pollution Types and Harm on EN Transformer Bushing Surface
Before implementing cleaning work, maintenance personnel must identify pollution types to select targeted cleaning methods. The first type is dry dust pollution, the most common light pollution in urban and rural power distribution environments. Long-term accumulated dry dust covers the bushing sheds and insulation surface, reducing surface hydrophobicity and easily forming conductive dirt layers in humid weather. The second type is sticky industrial pollution, including oil mist sediment, chemical powder, and industrial flue dust, which adheres tightly to the bushing surface and is difficult to remove with simple wiping.
The third type is salt fog and corrosive pollution, mainly found in coastal areas. Salt crystallization forms a highly conductive layer on the bushing surface, seriously reducing insulation performance and greatly increasing the probability of wet flashover in rainy and foggy days. The fourth type is biological and mixed pollution such as bird droppings and mold, which is acidic and corrosive, prone to causing local insulation tracking and permanent damage to porcelain glaze and resin surfaces. Different pollution types correspond to exclusive cleaning processes, ensuring thorough decontamination without damaging the EN transformer bushing structure.
Manual Dry Wiping Cleaning Method (For Light Dry Pollution)
Manual dry wiping is the most basic, safe, and widely applicable cleaning method, suitable for EN transformer bushings with slight dry dust accumulation and no sticky or wet pollutants. This method is applicable to daily routine maintenance and regular surface dust removal for both porcelain and epoxy resin EN transformer bushings, with no damage to the insulation surface and no impact on equipment operation status.
The standard operation process is straightforward and standardized. First, confirm the on-site safety environment and complete power-off inspection for live equipment to ensure construction safety. Second, prepare professional lint-free dry cleaning cloths and soft fiber brushes; avoid hard tools such as steel brushes and rough gauze, which can leave scratches on the bushing surface and damage the anti-pollution glaze and hydrophobic coating. Third, gently wipe the bushing shed gaps, outer surface, and flange connection area layer by layer, sweeping away floating dust and dry sediment completely.
This cleaning method features simple operation, low cost, and zero damage risk. It is recommended for monthly routine maintenance of indoor transformers and outdoor equipment in low-pollution areas. However, dry wiping cannot remove sticky dirt and salt crystallization, so it is only limited to light pollution scenarios.
Wet Cleaning Method With Special Insulating Agent (For Sticky and Moderate Pollution)
For moderately polluted EN transformer bushings with sticky dust, slight oil stains, and adherent industrial sediment, wet cleaning with professional insulating cleaning agents is the most effective solution. Different from ordinary water washing, special electrical insulating cleaning agents feature high insulation, volatile drying, and non-corrosive properties, which will not cause surface water film conduction or corrode bushing insulation and sealing components.
During operation, first dilute the insulating cleaning agent according to standard proportions and spray it evenly on the polluted surface of the EN transformer bushing. Allow 2 to 3 minutes of infiltration to soften sticky dirt and solidified sediment. Then use soft sponge and fiber cloth to wipe along the direction of the insulating sheds, cleaning the surface and gap dirt thoroughly. Finally, wait for natural volatilization and drying, ensuring no residual liquid remains on the bushing surface to avoid secondary leakage current risks.
This method is suitable for most industrial park transformers and suburban outdoor distribution equipment. It can effectively remove sticky pollutants that cannot be cleaned by dry wiping, while protecting the porcelain glaze and epoxy resin surface structure, maintaining the original creepage distance and anti-fouling performance of the EN transformer bushing.
High-Pressure Water Jet Cleaning Method (For Heavy Uniform Pollution)
High-pressure pure water jet cleaning is widely used for heavily polluted EN transformer bushings in coastal areas, chemical industrial zones, and dusty mining areas. This method adopts purified water with low conductivity and adjustable low-pressure water flow, which can quickly flush large-area salt crystallization, thick dust layers, and corrosive sediment without damaging the bushing insulation shell.
Strict operational standards must be followed during cleaning. The water pressure should be controlled within a safe range to prevent high-pressure impact from cracking porcelain sheds or deforming epoxy resin surfaces. The water jet angle should be parallel to the bushing surface to avoid direct vertical impact on the insulating skirt gaps. In addition, high-pressure cleaning is prohibited in rainy days, high humidity condensation environments, and low-temperature freezing weather to prevent residual water from freezing or forming conductive water films.
After high-pressure flushing, use dry fiber cloth to remove residual water stains and conduct ventilation drying treatment. This method features high cleaning efficiency and thorough decontamination effect, suitable for annual centralized maintenance of outdoor heavy-pollution EN transformer bushings.
Cleaning Prohibitions and Key Protection Rules
To avoid secondary damage to EN transformer bushings during cleaning, multiple prohibited operations must be strictly implemented. Never use corrosive detergents such as alkaline and acidic cleaning solutions, which will erode the porcelain glaze and resin surface, damage hydrophobic performance, and accelerate insulation aging. Never use hard scraping tools to remove stubborn dirt, so as not to cause micro scratches and surface defects.
In addition, cleaning operations are forbidden during equipment live operation, thunderstorm weather, and extreme high and low temperature environments. After cleaning, staff must inspect the bushing surface integrity, flange sealing status, and shed structure to confirm no damage, water residue, or dirt remains before restoring equipment operation.
Conclusion
Scientific surface cleaning is a key maintenance measure to maintain the insulation performance and operational stability of polluted EN transformer bushings. Different cleaning methods, including dry wiping, insulating agent wet cleaning, and high-pressure water jet cleaning, should be selected according to actual pollution degrees and scene environments. Standardized cleaning operations can effectively remove surface pollutants, restore the original anti-pollution and insulation capabilities of EN transformer bushings, reduce flashover and partial discharge risks, and ensure the long-term safe and stable operation of European standard oil-immersed transformers in complex operating environments.
