Certification

Rotor hub sensor NBT-D/S3 with SIL2/PLd certificate

Rotor hub sensor NBT-D/S3 with SIL2/PLd certificate

Another sensor from TWK joins the now long list of SIL2/PLd certified sensors: The newly developed NBT-D/S3 rotor hub sensor with Profinet interface. The sensor, which was primarily developed for wind turbines, measures the speed of the rotor so that the user knows the operating status of his turbine at all times. Due to the functionally safe design of the sensor, he can trust the output signal of the NBT at any time and design his control concept accordingly. Installation in the rotor is extremely simple and cost-effective: no connection to a drive shaft is required. Instead, it can be placed anywhere near the axis of rotation.

Arbitrary mounting is made possible by the use of MEMS sensors. The rotor hub sensor contains a high-precision gyroscope sensor that measures the applied speed (angular velocity). An additionally installed accelerometer serves to validate the speed signal and outputs the current angle on the 360° scale as the rotor position.

The interface of the sensor is Profisafe via Profinet, additionally equipped with the PROFINET standard module. This device was developed as a functionally safe safety version according to ISO 13849 and IEC 61508 with Performance Level d and Safety Integrated Level 2 with a service life of 25 years. Now the certificate from the TÜV certification body is also available. The user can be sure that he is installing a safe sensor that delivers reliable data. And in a double sense: metrologically and functionally safe.

The fact that the sensor can be mounted anywhere in the rotor of a wind turbine or in a similar application - without the need for a shaft connection - makes it much easier for the user to use. It required a new approach to measured value processing during development. The implementation of a Kalman filter for linking the measured values of the gyroscope and the accelerometer, as well as newly developed algorithms and correction filters, finally produced a very good result: a fast-responding and interference-tolerant speed signal of high accuracy. So far unique on the market.

The typical longitudinal and transverse vibrations occurring in a wind turbine as well as nacelle vibrations have little effect on the quality of the signal. Many tests in the laboratory and in the field were successfully passed, even with slight tilting from the plane of rotation. The measure of all things here was the high requirements of our customers. The first series applications have already been carried out.

The robust and weather-resistant sensor thus contributes to the safe operation of a wind turbine, for example to prevent damage caused by overspeed of the rotor. With its sturdy aluminium housing, it offers protection class IP67. The connection is made via M12 plugs.

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