Dwarfed by a fleet of sky-scraping wind turbines, one might not realize there are up to 20 brakes installed in each one. They are typically rotor brakes and yaw brakes, while, on the electric pitch systems, there are pitch brakes on each drive motor.
In the fast-paced, wind-power world, when up-tower, it is important to minimize downtime and take up exactly what is needed — first time. For example, when working around nuclear installations, it’s necessary to have detailed tool lists and extensive pre-planning meetings to avoid delays and reduce radiation exposure. In wind, the stakes are just as high.
Rotor, yaw, and pitch brakes
Rotor brakes are likely caliper-style (active or passive), while rotor lock style pins (hydraulic or manual) are used for safety locking and maintenance purposes. Yaw brakes (active or passive) and sliding bearings, along with special brakes, are installed for pitch movement on the blades. Then there are high-end coolers, hydraulic systems, cylinders, and accumulators.
Throw into the equation that modern-day turbines can reach to more than 850 feet and can be as many as 50 nautical miles offshore, and the scale of the task to keep thousands of braking systems operational, even on a single wind farm, starts to present itself. It means that brake manufacturers need to stay at the cutting edge of their own technological field, while leading the way in height safety best practice.
When high-end powertrain and braking components are involved, unscheduled maintenance is seldom required. This also means work can be planned and emergencies prevented. While manual checks on brake pad thickness and wear-and-tear are necessary, modern brakes have wear indicators that can alert maintenance teams of any issues ahead of time.
Unsung heroes
Each brake is a feat of engineering in its own right, and being able to examine one on a workbench takes years of training and practice. The fact that none of the tasks alluded to earlier ever takes place in the comfort of a workshop means plans must be made accordingly from the point of design all the way through manufacturing and application. Where ropes and hoisting equipment enable safe access to nacelles, tools are designed with lanyards to prevent dropped objects. If one is using a wrench or torque wrench to calibrate, think about what can happen if a worker suddenly slips. Damage to equipment, property, and personnel is the first thought at all times.
A wind-turbine nacelle is not always a comfortable environment to perform such labor. Certain places, such as the hub or lower yawing area, present particular challenges. Where, in the industrial sector, detailed work plans, including specific access and egress protocols, would be in place anytime a worker had to complete a job in a confined space, in wind energy, this environment is the norm. Much respect goes to tower technicians who stand, crouch, crawl, and climb to get jobs done. Some scoff, but they are totally deserving of the higher pay scales that the industry affords them.
Pressure on component suppliers
For a long time, the brake and component industry has tried to impart its knowledge onto wind-energy engineers, but the required expertise largely remains within the product sector itself. While the installed base of wind farms in the U.S. tends to be onshore, more offshore farms are starting to be approved and built. This only adds to the pressure on component suppliers.
As suggested, once competent on brakes, a technician must also be a pioneer in height safety. Safe work at height and climbing to get there involves extensive training and a thorough understanding of the requirements for ascent, descent, and everything in between. It’s not an environment where one can only think about themselves, either; support, rescue, and emergency plans must also be rehearsed and constantly retrained.
I have been throwing on harnesses all my career to work on electric overhead traveling (EOT) cranes, but until going to a wind power-related training class some years ago, I had no real understanding of the evolution that has taken place in climbing, rigging, and height safety. It was eye-opening and concerning in equal measure.
Next time you’re in the field, looking up at a wind turbine and take a moment to think about the abundance of heavy-duty rotor, yaw, and pitch brakes in operation, and the expertise required to access them and keep everything working safely and efficiently. A truly worldwide operation, Dellner adopts a “think globally, act locally” mentality, which enables the company to operate almost seamlessly at wind turbines turn across the world. Technical teams from China, India, Denmark, Germany, Spain, and the U.S. make sure that, if required, Dellner can be on site at a moment’s notice.
