After transformer bushings have reached the end of their service life, they should be handled through system assessment, safe dismantling, classified processing, and compliant disposal. Priority should be given to ensuring the safe operation of the power system, while also considering environmental protection and resource recycling value.
Standard Handling Procedures After Service Life Expiration
Conducting Condition Assessment and Inspection
Specialized inspections should be conducted on bushings nearing or exceeding their design life (usually 30–50 years), including:
Insulation performance testing (e.g., dielectric loss, partial discharge)
Sealing inspection (oil leakage, flange seal aging)
Porcelain bushing visual inspection (cracks, dirt, flashover marks)
If the test results are abnormal or there are safety hazards, replacement procedures should be initiated even if the bushing is not completely failed.
Safe Dismantling and Oil Sampling Operation
Power must be disconnected and reliably grounded before dismantling to ensure operational safety.
For oil-filled bushings, an oil sample should be taken for analysis to determine the degree of internal aging. Use specialized tools when extracting oil to avoid contamination or leakage: Clean the flange oil plug and screw in the oil nozzle to extract oil. Restore the seal promptly after oil extraction to prevent water and air ingress. Protect the measuring terminals during disassembly; never open the circuit during operation.
Classification and Resource Utilization of Used Components
Removed bushings are classified and processed according to material: Metal components (guide rods, flanges): recyclable. Insulating materials (porcelain bushings, epoxy resin): disposed of according to solid waste regulations. Oil-containing components: require professional degreasing treatment to prevent environmental pollution. When the transformer is completely decommissioned, it can be meticulously disassembled; the recovery rate of high-value materials such as copper windings can reach 60 kg/50kVA transformer.
