Transformer life extension by continuous on-line oil conditioning

On-line oil conditioning of transformer oil was used to remove components responsible for promoting deterioration of the oil/paper insulation system, including moisture, acids, degradation products, particles and gases. By preventing their accumulation, the life of the paper/oil insulation will be extended. A system was designed and built using a combination of adsorbents and semi permeable membranes and equipped with simple self-controlled fail-safe features for unattended operation. Several prototype conditioning units were built and tested in the laboratory and in the field with in-service transformers. Results showed these units substantially improved the quality of the oil. Some units may also be operated in a degassing mode to remove dissolved gases and moisture.