The primary purpose of transformer maintenance is to ensure the internal and external parts of the transformer and accessories are kept in good condition and “fit for purpose” and able to operate safely at all times. A secondary and equally essential purpose is to maintain a historical record of the condition of the transformer.

Transformer maintenance can be done periodically or as condition based maintenance. The latter is usually the most economical way of doing maintenance.

Recommended maintenance are then done based on one or more of the following: inspections, analysis of oil samples, electrical measurements, test of equipment, measurement of temperatures by using a heat sensitive camera, monitoring (off-line and/or on-line).