Elektronic oscillation monitor with safety relay

Maintenance-free and wear-free measurement of low frequency ranges

Even though conventional, mechanical oscillation sensors provide reliable measurement in the high frequency range, they experience problems with low frequencies as produced in wind turbines. For this reason, the Lenord + Bauer tower oscillation monitors work with micro-electro-mechanical systems (MEMS), which acquire oscillations in a frequency range of 0 to 10 Hz.

Simply put, a freely moving mass is suspended in the sensor element. In idle state, it is maintained in a middle position between two stationary reference electrodes by springs. Acceleration of the mass takes place via oscillations or vibrations; the mass moves and expands or contracts the springs. As soon as the acceleration decreases, the springs push the mass back into starting position. Technically, the output measured value is an acceleration value. Hence, the tower oscillation monitors are also referred to as acceleration sensors.

The MEMS are so small that it requires extreme magnification to make their structure visible. The robust sensors are not subject to ageing, and provide wear-free and maintenance-free operation.

Integrated safety relay activates safety circuit in wind turbines

The acceleration sensors from Lenord + Bauer are mainly used to measure the tower oscillation of wind turbines. They are extremely robust, dew-point resistant, and in accordance with IP 67. Therefore they are also suited for use in hot and cold climate regions, installation altitude up to 4,000 m, and offshore.

The measured values are transferred to the plant control either via a CANopen interface or EtherCAT interface. If the measured values exceed the limits, the safety circuit of the wind turbine is activated via an integrated relay with mechanically interlocked contacts. Thus, dangerous resonance effects are reliably detected and measures to avert the danger are initiated.

Redundant measuring system with high Safety Integrity Level

Due to their high MTTF figures, the tower oscillation monitors have a high Safety Integrity Level (SIL)http://de.lenord.netzpepper.de/service/glossar/glossary_record/siland Performance Level (PL)http://de.lenord.netzpepper.de/service/glossar/glossary_record/pl. Since this concerns a safety-related component, the sensors are designed as redundant measuring system that is equipped with two independently working (MEMS)http://de.lenord.netzpepper.de/service/glossar/glossary_record/mems.

Here you will find further information on our tower oscillation monitor:

Are you searching for a suitable acceleration sensor for your application?

Lenord, Bauer manufacture customised sensor types in such a wide variety that the sensors often only differ in technical details from one another. For this reason Lenord, Bauer have only introduced the standard types of this series here. However, if you have questions about a specific product, you can contact our technical support team at any time in iran .

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