Retrofitting turbines before end-of-warranty

New Zealand-based Meridian Energy wanted to ensure their four-year-old wind farm's continuous viable, renewable energy production. In 2010, they chose to retrofit 29 turbines with TCM^®. Over eight months, Meridian identified faults that resulted in saving upfront costs of five gearboxes, amounting to a total cost savings of USD 2,690,000.

Predicting and planning maintenance with TCM^®
Meridian Energy wanted to avoid damage and complete failure of the wind turbine gearbox. Therefore, retrofitting their wind turbine fleet with TCM^® would help them monitor the condition of the bearings and detect damage early.

“TCM^® enables us to plan maintenance and downtime and to order spare parts in time, particularly since we tend to have long lead times on parts out of Europe”, explains Helen Steward, Mechanical Engineer (Wind), Meridian Energy. 

With Meridian’s desire for early failure detection and readily available parts for scheduled downtime, the retrofit project started in the fall of 2011 and was completed in the spring of 2012.

With TCM^® in place, Helen Steward and her team were able to identify the first signs of damage, as she explains:

“Before end-of-warranty at one of our wind farms, we decided to retrofit KK Wind Solutions' TCM^® in our turbines. We installed TCM^® about eight months before the end-of-warranty. Over that time, data collected was analyzed and used to prioritize where video scope inspections should be carried out.”

In this picture, Thomas Pedersen was on-site to supervise the installation and help with the M-Systems' commissioning.
 

IMS & HSS early damages revealed 
Increasing vibration levels were observed in five turbines, which correlated with IMS bearing damage to the inner race. Meridian conducted visual inspections that confirmed the findings and showed the early stage of failure. As a result, Meridian was able to keep the turbines running until new bearings arrived. The downtime was scheduled, and the bearings were replaced in-situ under warranty.

Similarly, TCM^® indicated an inner race fault on three HSS bearings. Meridian’s team carried out visual inspections, but no visible damage could be found due to restricted access. Meridian continued to run the turbines but ordered three replacement HSS bearings.

When Meridian replaced the three bearings, they visually inspected the removed inner raceways. They found two hairline cracks on one inner race, and the other two bearings underwent crack testing.

“TCM^® allowed us to identify bearing damage before it became significant enough to cause secondary damage in the gearboxes. We were able to order the bearings and plan turbine downtime to change the current bearings. Having such advanced warning of failures is crucial in maintaining turbine availability and avoiding high replacement costs associated with complete gearbox failure.” - Helen Steward, Mechanical Engineer (Wind), Meridian Energy