Colombian generator repaired with new windings

M&M Bobinados Industriales based in Valle del Cauca, Colombia, offers a complete service for generator and motor repairs including balancing and electrical testing.

As part of a recent project, M&M called on the design and manufacturing company Sulzer and its Service Centre in Birmingham, UK, to produce 160 new, large coils for an 11,000 kVA generator.

Benny Hinchliffe, Head of International Operations at Sulzer UK, explained: “Our coil shop is supported by an expert design team that can analyse the original coil design and apply the latest insulation technology to produce a much more efficient coil. In this case M&M completed one of our datasheets and also sent one of the original coils to the UK so we could double-check every dimension.” 

Having ascertained the required dimensions of the finished coil, Sulzer’s designers created a 3D computer model of the coil and, by introducing the latest insulation materials, were able to redesign the coil while increasing the volume of copper by 12%. This increase in copper effectively improved the efficiency of the generator by a similar figure. The new design was also created for a ‘best-fit’ which would eliminate the need for side packers in the stator slots, making installation quicker and easier.

The coil shop uses its own in-house facilities to draw and anneal the base copper before manufacturing the insulated copper strips. This enables very short production schedules, especially since the shop runs 24 hour shifts, if necessary, and new coils are air-freighted to the customer after passing all of the inspections and electrical tests.

Danny Fox, Business Manager, Formed Coil Manufacturing at Sulzer, commented: “The new coils for M&M were created by looping the copper strip to form a full size coil. It was then carefully shaped to the exact dimensions of the stator. Our looping machines have the capacity to produce 5m long diamond coils and we also have the capacity to press slot sections of up to 6m in length on our half bars, meaning the entire bar length can be anything up to 7-8m including their overhangs.”

Fox continued: “A high degree of automation and the continuous quality control checks throughout the processes ensure that each and every coil is formed to exactly the right size and shape. The design also includes a precision-built mock-up of a section of the stator, which is used to double-check the final fit of every coil before it is shipped to the client.”

Ulises Osuna, Technical Manager for M&M Bobinados Industriales, said: “We have been involved with the manufacture and installation of high voltage coils for over 45 years and the coils we received from Sulzer were the best coils we have ever installed. The improvements in the design have certainly reduced the installation time as well as improving the efficiency of the generator, which makes the coils very cost effective for the client.”