The general rule
The bigger and more specialised the motor, the more likely a rewind makes sense. A small, common motor may cost little more new than a rewind; a large or unusual one — an odd frame, a special shaft, a machine built around it — is often far cheaper to rewind than to replace.
Questions that decide it
Ask these, in roughly this order:
- Is the stator core sound? A core that was badly overheated or rubbed by the rotor may not be worth rewinding.
- Are the frame, shaft and bearing housings in good order?
- Is a replacement easy to get, and does it fit the same mounting and shaft?
- How long can the machine stand idle? Compare the rewind time with the delivery time for a new motor.
- Has this motor failed before? Repeated failures point to a cause outside the motor.
A good rewind
A proper rewind copies the original winding data — turns, wire size, connection — or corrects it if it was wrong. It uses insulation of the right class, is varnished and baked, and is tested before it leaves: insulation resistance, winding resistance, and a no-load run. Ask what tests are done.
Do not skip the cause
Windings rarely fail for no reason. If the motor burnt out from overload, single-phasing, low voltage or blocked cooling, fix that too — a protection relay, a phase-failure preventer, a cleaner installation. Otherwise the new winding meets the same fate.
General guidance only — every installation is different. For work on live equipment, use a licensed electrician. Last reviewed 28 September 2026.