Vibration sensor NVA/S3 PLd


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Vibration sensor NVA/S3 PLd - 1

SUPREME SENSORING TWTC Document No.: NVA 13482 ME Date: 21.03.2019 CflNopGQ safety Certified EN ISO 13849: PLd ■ Contactless, wear-free sensor system in MEMS technology ■ Number of measurement axes: 2 ■ Frequency range: 0.1 ... 60 Hz (opt. 0.05 Hz) ■ Measuring range: ± 2 g ■ Interfaces: ♦ CANopen safety PLd ♦ 2 switching contacts PLd ■ Special features: ♦ Type of filter selectable ♦ 'Safety Shut off' SSO due to heavy strokes ♦ "Switch off phasing" adjustable ♦ Various signal settings (RMS etc.) ■ On request ♦ 'FFT' - fourier frequency detection ♦ 2 analogue outputs Design The sensor system is intended as a component for use e.g. in wind power plants to measure and evaluate vibrations in the mast head. Registration of dynamic accelerations by means of MEMS sensors (Micro-Electro-Mechanical System) with subsequent digitisation by a controller. The device consists of an acceleration sensor, a controller unit and three types of output interface. The main feature is two safety switching contacts (potential-free), which can be used e.g. in the safety chain to undertake safety shut-off in the event of excessively high acceleration values. Data output is carried out via the CANopen interface. The standard or the safety profile can be selected. There are additionally two analogue outputs 4 ... 20 mA, which can be optionally assigned to two of the three measurement axes. Thanks to its high resistance to vibration and shock, the sensor is suitable for use in areas with rough environmental conditions. Electrical connection is carried out using two or three connectors. Function MEMS sensors are integrated circuits which are manufactured in silicon bulk micromechanics technology. They have a long service life and are very robust. After determining the steady component and scaling, the measured values supplied by the acceleration sensor are made available to the six filter units. The steady component arises as a result of installation which is not precisely horizontal, with the result that part of the earth's gravitational field would also be measured. The offset which occurs in the measured vibration value curve (zero point shift) due to the steady component is determined by means of calculation (distribution of the positive and negative measured values around the zero point) and is subtracted. The pure alternating component is output within a matter of 20 seconds. This calculation takes place continually. This function can be shut off in the factory. The filter units can be individually programmed in the filter characteristics for frequency selection in the factory (low pass or band pass). They can be assigned to axes x, y or the resulting ones. Certain types of filter (kind, order, frequency limits) can be defined by the customer and can then be selected via CANopen. The signals which are then available can be used for: ♦ activation of the safety switching outputs, time delay on demand (g limit values and assignment) ♦ output on CANopen / CANopen safety ♦ selection of momentary or RMS output or peak or integral output ♦ output on analogue outputs (not certified) (amplification factor and assignment) The majority of parameters can be set using the CANopen interface. TWK-ELEKTRONIK GmbH BismarckstraBe 108 visit us at |

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Vibration sensor NVA/S3 PLd - 2

See document NVA13660 for detailed information General information The vibration sensor measures on two axes in a frequency spectrum from 0.1 to 60 Hz (Option: 0.05 to 60 Hz). This spectrum can be subdivided into a maximum of 6 frequency ranges. The frequency ranges are set in the factory. All acceleration values acting within the relevant frequency window are registered and are output firstly as an analogue value (4 ... 20 mA, max. two outputs possible) and secondly as a digital value via CANopen or CANopen safety. The acceleration values which are present are additionally compared with...

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Vibration sensor NVA/S3 PLd - 3

SUPREME SENSORING Examples for fiter output Amplitude vs f Diagram for analogue output I0(a) Output: signed ■ x, momentary value ■ y, momentary value Block Diagram x or y, RMS value x or y, Peak value S=V(x2+y2), RMS value S=V(x2+y2), momentary value Integral 1 or 2 Following version is shown: CANopen + Analogue + Switches Date: 21.03.2019 Page 3 of 15 Document No. NVA 13482 ME

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Vibration sensor NVA/S3 PLd - 4

Frequency detection by Fourier transformation FFT NVA version which provides the output of the spectrum of measured frequencies via CANopen. This spectrum is get by Fourier transformation (FFT) of the momentary value of the acceleration measurement versus time. This functionality can be used for blade or tower frequency detection. See two simple examples for such a transformation as well as a real spectrum are shown in the following diagrams. Amplitude The spectrum of FFT analysis is transmitted to the turbine controller CANopen object 340x, sub C. The controller can evaluate this...

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Vibration sensor NVA/S3 PLd - 5

Safety - PLd - NVA / S3Programmable features Parameters programmable via CANopen interface ■ Measuring axis: x, y or V(x2+y2) separately for each filter (means output) 1 - 6 ■ Filtertype which is prepared by TWK due to customers requirements for each output 1 - 6 ■ Signal type at filter output 1 - 6: momentary value, RMS mean value, peak value, integration value ■ Averaging time for signal type 'RMS', degressive time for peak, integration time ■ Amplification for analogue outputs 4 ... 20 mA (Analoge outputs are assigned to filter 1 and 2) * ■ Acceleration limit values (limit) for relay...

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Vibration sensor NVA/S3 PLd - 6

Signal acquisition ■ Number of axes: ■ Value output on analogue output: ■ Number of frequency bands: ■ Measuring range: ■ Sampling frequency: ■ Accuracy of the measured acceleration value: ■ Maximum inclination vs. horizon: ■ Lower limit frequency: ■ Upper limit frequency: ■ Set-up time: 2 x and y as separate components or vector sum of x and y (resulting R) maximum of 6 (Setting ex works) ± 2 g for each axis (higher values on request) 120 to 800 Hz, depending on the frequency range of according filter Standard 5 % (typically) 15° (at angles >15° an error message will be transferred by...

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