1300kW Motor Rewind Completed in 30 DaysApril 23, 2020 by Paul Shepard
Industrial manufacturing plants rely on shutdown periods to complete planned maintenance activities without impacting on productivity. However, when large assets need a complete overhaul, delivering these projects within such a short timeframe can be a considerable challenge. Sulzer delivered complete rewind project for fertilizer manufacturer in 30 days to match shutdown period. Pictured above is the balancing of the rotor prior to reassembly.
Even the most urban of us rely on well fertilized soil. From the food we eat to the celebratory bouquet – plants need good soil. Everything that we farm is only as good as the soil that it is grown in. Fertilizers help farmers create nutrient-rich soils, which in turn will promote the growth of healthy plants.
Keeping farms supplied with fertilizer requires reliable production. This means that every part of the manufacturing process needs to be maintained and periodically checked. One of the main projects was to completely rewind a 1300kW motor that powered a CO2 compressor during a planned shutdown period. As an aging asset, it had been identified for refurbishment to extend its reliable service life and the rewind option was more cost-effective than replacement.
Shutdown periods provide an extended opportunity to carry out maintenance as well as refurbishment and upgrading work. As such, they allow companies to improve the performance and reliability of their equipment without affecting productivity.
The customer has often called upon Sulzer’s expertise and fast turnaround to deliver repair projects. In this case, the advanced notice of the rewind provided some additional planning time, but the dimensions of the new stator coils could not be established until the motor had been removed from service.
Rapid coil manufacturing
Sulzer’s in-house coil manufacturing facility, which is located in the Birmingham Service Center, offers round-the-clock production runs to ensure even the tightest deadlines are met. Having received the coil measurements, the design engineers were able to create the necessary drawings that would also deliver improved efficiency and performance for the refurbished motor.
In cases such as this, where a motor has been in service for a few decades, the coil insulation will be of a lower specification than the materials used today. Sulzer uses its design expertise to incorporate Class F insulation, which is thinner than the original materials. To fill the gap that would otherwise be present, additional copper is added to each stator coil to ensure a perfect fit.
This additional copper also provides an incremental increase in efficiency as well as helping to reduce the operating temperature of the coils. By improving efficiency, the design modification also helps to reduce annual running costs.
Paul Richardson, Middlesbrough Service Center Manager explains: “The advantages of having our own in-house coil manufacturing facility were highlighted during this project. Given the very tight deadline for the rewind, it was essential that we started the coil manufacturing process as soon as possible. This can sometimes be a bottleneck for a project, especially if you are relying on an external supplier.”
In all, 60 coils were manufactured in Birmingham and shipped to the Middlesbrough Service Center, where they were installed into the stator. This is a complex operation and the engineers worked through the night to complete the brazing, taping, varnishing and testing, before the motor could be returned to the customer.
One of the engineers at the site commented: “We have developed an excellent relationship with Sulzer and trust them to deliver many of our maintenance projects. In this case, we only had a 30-day window to complete this rewind and Sulzer managed to deliver on time so our operation could restart promptly.”
Paul concludes: “From the outset, there were several comments that this rewind could not be completed in 30 days, but we have shown that with the necessary commitment and cooperation, expectations can be exceeded. Sulzer’s expertise and flexibility have proven to be invaluable on this project.”