Repairing transformer may be most economical and efficient option for keeping the power on, particularly can't wait for new production lead times, and reconditioned units are not readily available.

Overhauling of a transformer is normally undertaken either if it is faulty or at the end of 10 - 12 years periodic maintenance. It is advisable to review and analyze the periodical DGA values to check any abnormal variation and healthiness of the transformer.