Cashing in with TCM® Retrofit

How Meridian Energy Ltd. proved that retrofitting their turbines before end-of-warranty was well worth the investment.

Project Background
When Meridian Energy came to us in 2010 with the task of extending their TCM® fleet by retrofitting 29 turbines in New Zealand, we took hold of the opportunity. Meridian Energy provides wind-generated electricity to an average of 152,000 homes a year in New Zealand. In a country where there are no government subsidies provided for wind power, New Zealand’s largest electricity provider, Meridian wanted to ensure viable renewable energy production, and therefore decided to retrofit their four year-old wind farm with TCM®.

The Ultimate Decision
When Meridian’s Helen Steward was asked why they decided to retrofit their 29 turbines with Turbine Condition Monitoring, she replied, “primarily to monitor the condition of the bearings in order to detect damage early, so that we could hopefully avoid consequential damage and complete gearbox failure. Also, to enable us to plan maintenance and downtime and to order spares in time, particularly since we tend to have long lead times on parts out of Europe.” With Meridian’s desire for early failure detection and readily available parts for scheduled downtime, came their commitment for using TCM® and the commencement of the retrofit project in the fall of 2011.

After the successful installation was completed in the spring of 2012, Meridian’s own Mechanical Engineer, Helen Steward was able to catch the first signs of damage . . .

“Prior to end of warranty at one of our wind farms we decided to retrofit Gram & Juhl’s TCM® in our turbines. We installed TCM® about eight months before the end of warranty and over that time the data collected was analysed and used to prioritise where videoscope inspections should be carried out.

Increasing vibration levels were seen at five turbines, which correlated with IMS bearing damage to the inner race. The visual inspections confirmed the findings and showed the early stage of failure. As a result we were able to keep the turbines running until new bearings arrived. Downtime was scheduled and the bearings were replaced in-situ under warranty. Similarly, TCM® indicated an inner race fault on three HSS bearings. Visual inspections were carried out, but due to restricted access no damage was found. We continued to run the turbines but ordered three replacement HSS bearings. When we replaced the three bearings, we visually inspected the removed inner raceways. On one inner race, two hairline cracks could be seen. The other two bearings are undergoing crack testing at present.

TCM® allowed us to identify bearing damage before it became significant enough to cause secondary damage in the gearboxes. This allowed us to order the bearings and plan turbine downtime to change out the bearings on-site. Having such advance 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 Limited

The bottom line: In the course of eight months, Meridian was able to save five gearboxes with TCM® Retrofit, amounting to a total cost savings of $2,690,000 USD!

Gram & Juhl was on-site to supervise the installation and to help with the commissioning of the M-Systems.