RENEWABLE ENERGY
then deteriorates until failure occurs. Replacing the disc can be a time- consuming procedure involving cranes, which increases costs, downtime and reduces energy output. Resurfacing the disc uptower is another option, but that requires specialist equipment. Te portable disc resurfacing tool enables uptower operation to be carried out on site with increased speed while not compromising the refurbishment. Featuring a milling machine that quickly replanes the disc, the tool can operate inside the turbine nacelle, thanks to a compact and lightweight design. Simply mounted onto a yaw brake mounting position, the tool eliminates the need for nacelle disassembly. Tis eases maintenance work, while maximising energy output via reduced downtime and minimising cost.
REDUCING LOCAL IMPACT One of the barriers to the widespread adoption of onshore wind turbines has been local resistance to installations. While an exceptionally green technology, wind turbines do have an environmental impact. Problem areas include noise and dust from turbine yaw brakes. Two aftermarket solutions from Altra Renewables tackle these issues head on. Noise created by onshore wind turbine brakes can disturb both local residents and wildlife. Often this noise is a result of the glazing phenomenon. Like the brakes on a car, when there is no wind and low usage, yaw brake discs begin to collect dirt, rust and moisture as temperatures fluctuate. When the wind returns and braking begins again, this detritus is collected by the brake pad. Under braking force, it is pressed tightly into the pad, creating glazing. Eventually, the friction coefficient of the brake pad itself is compromised, while the disc becomes contaminated and slippery. Braking performance is greatly reduced and potentially produces excessive noise in operation. Once accrued, this glazing is difficult to
remove. In the past, removal would require complete brake disassembly, with the manual cleaning of each pad carried out by an angle grinder. Tis highly inefficient method also carries the penalty of producing even more noise. Te other option is pad replacement, but with the disc already contaminated, this is only an expensive interim solution. Altra Renewables has solved this problem with its Groove Tool, which
reduces yaw brake noise. Tis device cuts grooves in the yaw brake disc, which acts like a razor as the turbine moves to meet the wind, cutting detritus from the brake pad. A brush located between brakes removes debris from the grooves, allowing the disc to clean itself, helping to safeguard braking performance. Tis permanent solution is adapted to meet the specific needs of any given turbine. Taking into account wind direction, turbine diameter and disc material; Altra Renewables feeds data into computer programmes to ascertain the optimal number of grooves, groove position, shape and angle. Tis ensures that the technology is equally effective for preventing glazing on coastal turbines with two wind directions or turbines in the mountains where wind can come from any direction.
CLEANING UP YAW BRAKE DUST Reducing harmful dust produced by braking systems has been a focus of the automotive industry for many years. Until now, the onshore wind sector has been slow to catch up. Brake dust can
Onshore wind turbines present multiple challenges with regards to maintenance
contain potentially harmful substances that present a contamination risk to the local environment. Te dust also presents a risk to maintenance personnel who come into close contact with it. At large installations with multiple turbines, choosing an environmentally friendly brake pad material can deliver a large improvement with regards to protecting the local environment and on-site personnel. Specially developed in-house by
Svendborg Brakes to solve this problem, Green Alternative yaw brake friction material meets restriction of use of hazardous substances (REACH) standards adhered to by the automotive industry. Te material is asbestos-free, while containing less than 0.1% mercury, less than 0.1% chromium 6+, less than 0.1% lead and less than 0.01% cadmium. Furthermore, it is corrosion resistant and produces inherently less dust than traditional friction materials. Tis ensures that environmental impact and risks to maintenance personnel from yaw brake dust are greatly reduced.
The Groove Tool reduces yaw brake noise, by cutting grooves in the yaw brake disc, which acts like a razor as the turbine moves to meet the wind, cutting detritus from the brake pad
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