Vibration Monitoring in the Wind Power Industry
Wind Power Industry Whitepaper
With the growing emphasis on the use of wind energy to provide a higher percentage of electricity consumption worldwide, Hansford Sensors has found this developing market an excellent opportunity to promote the use of accelerometers.
The rotating parts of wind turbine generators need to be continuously monitored to warn of bearing and component wear. As wind turbines are frequently installed in remote locations with high costs incurred when failures occur, it is vital to determine potential problems before they arise so remedial action can be taken.
Hansford Sensors has approached this market with various products dependent on end user and OEM requirements and has supplied many thousands of accelerometers worldwide to power providers and specialist windmill monitoring companies.
Technical Requirements and Installation Considerations
Before detailing the equipment that has been installed, it is necessary to cover the technical requirements and installation issues encountered in windmill applications.
As a general rule, each windmill has eight accelerometers installed on the machine. Some applications have used an improved response, low frequency version of the HS 100 family, the HS 100SF, for monitoring lower movement such as low frequency tower movement.
Depending on customer requirements, accelerometers have either been supplied as 100 millivolt per g units or, in some cases, with two higher sensitivity units rated at 250 or 500 millivolt per g. These higher sensitivity sensors are used to monitor low speed aspects of the generator, such as output shafts.
Accelerometer Selection and Cabling Options
The HS 100 family has been used in various projects, with options including integral armoured cable and quick fit connectors.
The M12 side entry version has also been popular, with separate M12 cable assemblies of various lengths supplied as part of the package.
Mounting Techniques for Wind Turbines
Mounting techniques vary depending on the project.
In new OEM builds, most units have been supplied with M8 mounting. The mounting surface is prepared using spot facing and then drilled and tapped to M8.
In retrofit projects, where warranty issues apply, many accelerometers have been installed using adhesive mounting pads.
Junction Boxes and Signal Transmission
Most projects have involved supplying a local junction box to accommodate accelerometer cabling at the top of the windmill.
Depending on the configuration, multicore cable is connected and fed down to ground level for termination into the monitoring system or switch box.
Offline Vibration Monitoring Options
In applications where it has been difficult to justify the cost of a full online system, some wind farms have adopted a lower cost option.
This involves fixed HS 100 sensors mounted as described, connected via a local junction box and multicore cable to a switch box at ground level.
Vibration readings are then taken either by a contracted vibration analysis company or by an in house vibration analysis team. This method is only as effective as the most recent reading taken.
Expanding to Online Monitoring Systems
This offline approach provides a good foundation, as it can later be expanded into an online system when budget becomes available.
Expansion is achieved by replacing the switch box with a monitoring station capable of providing in depth vibration analysis using FFT with remote web access.
OEM Supply and Bespoke Solutions
Hansford Sensors also supplies OEM manufacturers of windmills and windmill monitoring systems.
In these cases, supply typically includes accelerometers, cabling, mounting pads, and related accessories based on previously defined specifications.
Many thousands of accelerometers have been supplied into this industry globally, with some projects involving bespoke designs to meet specific requirements.
Application Expertise and Technical Support
In bespoke projects, the Hansford Sensors team applies its knowledge of vibration monitoring directly to the application.
By working closely with customers, appropriate technical solutions are delivered at a cost effective price while meeting the demands of the wind power industry.
