Condition Based Maintenance (CBM) - Optimized Cost Saving

In the past, regular, scheduled maintenance used to be the norm. Whether it is a large wind turbine or your family car, oil was changed at rigid intervals. This has been shown to be an inefficient and expensive method in comparison with Condition Based Maintenance (CBM). In the case of wind turbines the difference between condition based maintenance and planned maintenance over a 10 year period is typically EUR 40,000 – that adds up fast with a large array. The added bonus is the environmental saving of less oil use and more efficient operation.

So, reduced costs, minimised downtime, optimised oil changes – everyone wants it but it is not so easy to achieve in the case of offshore wind farms. Instrumentation designers cmc Instruments GmbH worked with local academia to engineer a real time sensor system, WearSens^®. Now they have joined forces with offshore logistics experts Speedwind Offshore GmbH to bring the solution to windfarms.

Condition-based maintenance from continuous, online monitoring by the WearSens^® system from cmc Instruments provides,

• Detection of critical operating conditions

• Oil change on demand

• Damage prevention, increase turbine lifetime

• Real time information of oil condition and turbine stress

WearSens^® is easy to install, has a small footprint and is inexpensive to retro-fit. The decentralised, web based monitoring system makes results available anywhere in the world. It can be employed as a stand-alone unit or as part of a more comprehensive condition monitoring system.

Service provider Speedwind Offshore GmbH aim to deliver best-in-class practice for the condition based maintenance of offshore wind turbines. In line with the latest Health & Safety standards they have developed the SWOC 1.0 Container System and Service Modules.

The SWOC 1.0 is a 20-foot container equipped with two, separate, special hose systems for filling the transmission and hydraulic systems. A specially developed emergency coupling prevents oil leakage and avoids pollution of the environment. To stop thermal damage, the gear oil is preheated indirectly in a closed system to about 50°C before the pumping process.

The flushing oils are collected after the cleaning procedure and separated from all abrasive- and corrosive wear particles, water and oil deposits. This leads to a cost saving for the flushing process of up to 60%.

In the past wind turbines have been compromised by vibration, particulate matter in the oil system and cracks in the roller bearings. The only technology to measure these effects had detection limits such that damage had already occurred by the time the alarm was sounded. Rigid inspection intervals, sometimes unnecessary, are costly to perform, especially on offshore sites. Change the oil or replenish additives only when necessary. Rigid maintenance intervals can be a waste of money or they can be too late. With condition based maintenance from 24/7 monitoring huge savings can be made in money and man hours whilst optimising loads and achieving better lifetimes.

WearSens® is equally suitable for any large turbine. Applications have been realised in heavy industry, marine turbines and subsea applications.

cmc Instruments GmbH are a design, instrumentation and engineering company based near Frankfurt with extensive knowledge in tribology, oil aging mechanisms and instrument design.

Speedwind Offshore GmbH are a service manager of offshore vessels and maintenance. They can provide a one stop shop for contacts to suppliers, classification bodies and professional links.