Various industries rely on electric motors for their business operations and processes, from manufacturing to transportation, and more. Like every other machine, electric motors will eventually wear down from use, affecting operational performance and efficiency over time. This is where maintenance practices like motor rewinding come in to ensure your motor stays in top condition despite being in operation for years already.
Essentially, electric motor rewinds entail stripping off a motor’s old windings, replacing them with new ones, and insulating them to extend their lifespan and regain their original efficiency. Below, we quickly review some best practices regarding motor rewinding to improve your maintenance process.
1. Stator Core Processing
Rewinding can only be done if the essential components of the motor, particularly its stator core and rotor laminations, remain uncompromised. Thus, if an electric motor inspection test or core test reveals that the stator core has suffered damage, repairs must first be made before rewinding. If the laminations are flared, bending the teeth at the ends of their slot at the vertical middle is recommended. Furthermore, if the laminated material has some minor erosion, operators can restack the lamination in the eroded areas to fill out the gaps where the affected lamination has been damaged. Otherwise, lamination with severe damage requires a complete replacement.
2. Winding Practices
During winding, it is vital to maintain insulation resistance by using the same mean length of turn and wire area. Should there be enough space, operators can increase the wire area to reduce the gap between wires, allowing for better heat transfer capacity while reducing air pockets. This also reduces winding temperature and copper losses, resulting in greater efficiency and longer winding thermal life.
3. Mechanical Repairs
When procuring replacement bearings, they must be the same or equivalent to those of the motor’s OEM. Operators should also follow the proper installation procedure of the bearings to avoid rapid failure. Lastly, when filling the grease reservoir, make sure to only top it a third or half until full. If the motor’s surroundings warrant using sealed bearings, non-contact seals are highly effective at keeping out contaminants.
4. Ventilation Issues
Operators can increase motor fan efficiency by increasing the wire current capacity as much as possible, allowing a sizable reduction in fan size and windage loss. Any broken blades should be replaced with new ones, and the location and size of the fan cover should be configured in a way that does not reduce airflow.
5. Motor Design Aspects
Apart from any necessary slight increments, the new winding’s magnetic flux level should be left unchanged. Moreover, avoid replacing double-layer windings with a single-layer. If the rotor gets rebarred, the ring and bar materials should be duplicated and tested in terms of material resistance.
Conclusion
Motor rewinding from service providers of mechanical and electrical engineering in Singapore is the more cost-effective option for keeping motors in operating condition for years to come. With that said, no amount of rewinding can make a motor more efficient beyond its original design, meaning operational costs will remain high. Nonetheless, if a motor is still serviceable for its task despite being dated, motor rewinding is among the best ways to keep a motor performing like it initially used to.
