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NAM (Nederlandse Aardolie Maatschappij), a joint venture between Royal Dutch Shell and ExxonMobil, originated in the mid- 1990s. Its goal was to find the most cost-effective way to extract gas and extend the life of the Groningen gas field, ensuring that the field could continue to supply the region. The challenging parameters of the project were to provide availability of at least 87 percent and produce a low total cost of ownership. By following these parameters and upgrading the equipment, including the motors and compressors, the gas field could supply gas to all of Netherlands, Germany and Belgium for an additional 40 years.

User requirements were for high reliability, high energy efficiency, low maintenance and low investment cost across a wide compressor speed range with minimal vibration & noise. Waukesha Magnetic Bearings™ partnered with Siemens to initially install three radial active magnetic bearings for the motor, two radial magnetic bearings and an active magnetic thrust bearing on the compressor, and a digital controller with analog amplifiers. There have been a total of 20 installations since the initial installation. Waukesha Magnetic Bearings has produced the bearings for every installation even though the machines have varied significantly in terms of number of stages, hence the dynamics of the rotor. Waukesha Magnetic Bearings was able to adjust for these differences  through software in the controllers.

Compressor installation
23MW Motor on magnetic bearings

NAM’s original goal was to provide 87 percent availability with the lowest cost of ownership. Analyzing the results after 17 years confirms that Waukesha Magnetic Bearings has been able to exceed expectations, with over 99.9 percent availability and an investment cost savings of 35 percent, all while saving on energy costs.  There were many additional benefits to the system as well. Waukesha Magnetic Bearing’s system allows for remote monitoring, diagnostics and frequent fully automated remote start ups. It also provides superior investment protection through the use of bushing style auxiliary bearings that have never failed to protect the machine investment and retain the advantage of remote condition observability. Furthermore, by not using traditional fluid film bearings, additional building construction for a separate lubrication oil system for the bearings was not needed. This reduced costs and lessened the environmental footprint by providing a simpler, cleaner, more efficient design.