High-voltage bushings are critical components whose failure can have serious consequences.
Thermal and electrical stress, ambient conditions, and more are putting high demand on bushings. Because of the high electrical stress levels in bushings, failures in oil-impregnated bushings with porcelain insulators tend to result in sudden and catastrophic failure of an explosive nature.
Condition assessment and replacement of defect bushings, therefore, drastically reduce the risk of transformer failures. Certain types and applications may have a higher risk which is yet another reason for condition assessment. Knowing the health of your bushings allows you to take planned precautionary actions in time, be it in maintenance or replacement – all with the purpose of keeping your transformer reliable and online, supporting your network.
Little maintenance is required other than checking the oil level (if applicable), power factor and capacitance testing, and checking the condition of the top terminals. Bushings exposed to salt spray, concrete dust, and other abnormal deposits are subject to a special hazard and must be cleaned regularly to prevent flashover and corrosion of parts.
Oil-filled bushings may be considered for exchange to dry-type with composite insulators to reduce the consequences of failures and the need for maintenance. Repair of high-voltage condenser bushings is normally not economically justifiable. However, exceptions exist.
Hitachi Energy's offering includes installation, preventive maintenance, condition assessment as well as replacement or upgrades.