TWK (Germany) has introduced vibration sensors dedicated for wind power systems. It provides optionally a CANopen interface and measures in two dimensions the accelerations.
THE NVA/NVN DEVICES INTEGRATE AN MEMS (micro-electromechanical system) acceleration sensor. They measure accelerations caused by oscillations and vibrations. These measurements are converted into a proportionate output signal available at the CANopen interface. Relay switching outputs, which trigger if specific maximum acceleration values are exceeded, are also available in addition to the output signal. As in the case of the electronic switching cam encoder, this enables peripheral devices to be switched or alarms to be triggered. These are used in wind turbine masts, for example, to protect them from excessively severe vibrations. If necessary, they ensure that the system is shut off.
The sensor measures in two dimensions (x and y), in order to register all accelerations in a plane. Various frequency ranges from 0,1 Hz to 5 Hz can be selected or assigned with different limit values for the relays.
For safety purposes, the device is equipped with a redundant design. High-quality components are installed - e.g. guided relays and a 32-bit micro-controller - to ensure that all computations are processed reliably and quickly. The manufacturer also offering rotational encoders and inclinometers provides several enclosures for the vibration sensors. This allows installing them at different positions for different purposes. They may be used to detect imbalances caused for example by iced rotor-blades.
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