Rewind or Replace: The Efficiency Question
When an industrial motor fails, a familiar question arises: should it be rewound and returned to service, or replaced with a new one? The decision is often made on immediate cost alone, but a proper analysis that includes efficiency and running cost can point to a different, more economical answer.
The appeal of rewinding
Rewinding a failed motor, replacing its damaged windings, is often cheaper upfront than buying a new motor, especially for larger machines. The motor is already installed and its mechanical parts may be sound, so restoring it can seem the obvious economical choice. For many motors, particularly older or larger ones, rewinding is a long-established and sensible practice.
The efficiency consideration
The complication is efficiency. An older motor being rewound may be significantly less efficient than a modern replacement, and the rewinding process itself, if not done carefully, can slightly reduce efficiency further. Meanwhile, a new high-efficiency motor would waste less energy every hour it runs. For a motor that operates long hours, the energy saved by a more efficient new motor can outweigh the higher purchase price over time.
Weighing the whole cost
The sound approach compares the total cost of each option over the motor’s remaining life, not just the immediate outlay. Rewinding has a low upfront cost but continues the running cost of an older, less efficient machine. Replacement has a higher upfront cost but lower running cost. For a motor running many hours, the running cost dominates, and replacement with an efficient motor often wins; for a motor used seldom, rewinding may be the better value.
Making the decision
The right choice depends on the specific motor: its size, its efficiency compared with modern alternatives, and above all its operating hours. A large, hard-working, inefficient old motor is a strong candidate for replacement; a rarely used motor may be best rewound. Doing the running-cost comparison, rather than defaulting to the cheaper immediate option, ensures the decision serves the facility’s economics rather than just its short-term budget.
The rewind-or-replace question has no universal answer, but it does have a sound method: compare the full cost, including running cost and efficiency, over the motor’s remaining life. By considering efficiency and operating hours rather than upfront cost alone, a facility can make a decision that genuinely minimises cost, which sometimes means investing in a new efficient motor rather than restoring an old inefficient one.
