Articles

Oct 28 2014

Articles

Dem bones, dem bones, dem dry bones

I am about to experience my 10th surgery and this one will be the most major of all. I need to have a total knee replacement due to the gradual deterioration over time of its condition brought about as a result of previous serious sports injuries incurred whilst playing rugby and cricket. The knee itself although painful does not stop me doing too much however I have to compensate for its weaknesses with other parts of my body, the potential consequential damage to my hip, lower back and other knee caused by this compensation is the reason for the surgery.

What I hope this illustrates is that a fault in one area of your body or a system will always manifest itself somewhere else.  Everything is interconnected.

“The head bone’s connected to the neck bone”
“The neck bone’s connected to the shoulder bone”
“The shoulder bones connected to the back bone”

Sing along if you like; I’m sure you can work the rest out.

A wind turbine drivetrain is a system with multiple main components that are all interconnected with crucial support and connection points. Main bearings support the main shaft that runs between the rotor hub and the gearbox. The gearbox is supported by torque arm arrangements and the gearbox is connected at the high speed shaft  to the generator via various forms of couplings or connectors. Make up your own song if you want to.

If this is the case and we accept that what happens in one area of the drivetrain will directly impact another, then why when it comes to condition monitoring in a wind turbine drivetrain are so many still only monitoring part of the drivetrain and ignoring parts that directly impact others?

  • Main bearing failure will directly impact the planetary section of a gearbox.
  • Main shaft misalignment will also cause problems in the planetary section, and this will also be transmitted through to the helical section.
  • Generator misalignment or generator imbalance will directly impact the high speed bearings of a gearbox.
  • Degraded oil quality and oil contaminated with particles has a direct impact on bearing and toothed component life. 

All of the above will lead to (if you’re lucky) service in the nacelle or more often than not the removal of the gearbox and other components from the nacelle for workshop service. With a good Condition Management System, monitoring the whole drivetrain over 70% - 75% of drivetrain interventions are minor and can be made in the nacelle.  The remaining 25-30% that requires workshop service is for non-critical failures and the components can be refurbished and returned to operation.

Using no condition monitoring is now fortunately regarded by most as bad practice. Using condition monitoring that only focuses on vibration in one part of the drivetrain is better than nothing but ignores the interconnected nature of the drivetrain and the direct impact one part of the drivetrain will have on another. Using joined up monitoring – or management as we call it - provides earlier and clearer recognition of symptoms that go on to cause failure. The earlier this recognition the more time we have to react and the easier the preventative intervention needed is.

My right knee is the problem, my right hip and left knee are telling my brain that there is a problem. My body is interconnected and my nerves are the sensors.  My brain has told me it’s time to do something before one problem causes multiple long term problems elsewhere. My orthopedic surgeon will solve the original problem with some new parts and prevent other areas of my body failing. 

At Moventas we have CMaS, the interconnected, intelligent drive train condition management system. This is the nerve system for your drive train. We also have the brains and the surgeons in our engineering analysis team, on site engineers and technicians.

David Moss
Moventas Service

The author is the Sales Manager for UK & Ireland at Moventas Service. This article was published in the October 2014 issue of the Wind Energy Network magazine.

About Moventas

Moventas is a wind gearbox technology expert and service provider. Moventas’ technology strives for lowering the cost of energy across the lifecycle of wind energy generation, from superior gearbox design and manufacture to extensive multi-brand service for 20 different turbine brands' gearboxes globally.