Thordon SXL Series Bearings for Norwegian Hydroelectric Power Station

As part of the modernization of the Norwegian hydroelectric power station Raanaasfoss 1, new turbines were installed with Thordon SXL series water-lubricated guide bearings, which even after 23,887 hours (33 months) of continuous operation showed virtually no wear.

In 2013, Voith Hydro upgraded the Raanaasfoss 1 hydroelectric power station, which was built back in 1922, by installing new 13.5 MW turbines where water-lubricated guide bearings were used. During planned inspections of the turbines put into operation, it was found that the Thordon SXL series guide bearings showed almost no wear with a measured bearing clearance of less than 0.30 mm on the longest running block 1. All other turbines (blocks 2-6) had very low measured diametrical clearances from 0.30 to 0.50 mm. The initial design clearance of the SXL guide bearings was 0.65 mm.

“We are very pleased with the operating results of the water-lubricated guide bearings. Compared to oil-lubricated systems, maintenance and monitoring have become significantly less time consuming. Operating costs have also declined since we no longer need to buy lubricants, ”said Bj?rnar Petersen, mechanical engineer at Akershus Energy, which owns the hydropower plant. “Although economic factors were key when deciding on the choice of bearings, environmental issues were also the focus of attention.”

Choosing a water-lubricated solution for the lower guide bearing instead of the more traditional oil-lubricated design allows the bearing to be cooled and lubricated with the same river water that feeds the turbine.

Water-lubricated bearings completely eliminate the risk of oil leakage contaminating the turbine drain or associated water, which could happen with old bearing assemblies. A water-lubricated bearing not only helps protect the environment, but also provides operational and maintenance benefits over original oil-lubricated bearing systems. In particular, for Thordon bearings, downtime for inspection is extremely reduced. In addition, experience has shown that they work 3-4 years longer compared to oil-lubricated counterparts.

Many operators who previously switched to Thordon water-lubricated hydrodynamic bearings have already recouped their costs by saving on lubricants and a longer service life.