Vibration sensor with self-test



The vibration velocity sensor BVS420 is used for permanent monitoring of the vibration strength of rotating machines in accordance with DIN / ISO 10816. The sensor delivers a 4...20mA current loop signal analogous to the rms value of the vibration velocity. This current signal can be connected directly to standardized MCR technology, such as limit value relays, PLC, etc. As a special feature, this sensor has a self-test input, in which the internal sensor element is electrostatically charged and thus the entire sensor is tested. The output signal goes to > 20mA.




The BVS420 is housed in a watertight stainless steel housing. For attachment to the machine there is a M8 threaded hole in the bottom. A threaded bolt M8x20 for screwing into a blind hole is included. The electrical connection is made via a 4-pin M12 flange plug.





The sensor is used wherever machines have to be continuously monitored for their imbalance, such as fans, compressors, centrifuges, blowers, vibrators, decanters, separators,drives, gears, mixers, conveyors, tooling, machining and production machines, etc. and the monitoring of forced vibrations, such as vibration conveyors and electroplating baths.





1          +12…28V

2          Self-Test Input

3          Output 4…20mA

4          not connected




Conventional 4...20mA vibration sensors serve 4mA in quiet. This current signal (or a higher one) should indicate that the sensor and the wiring are in order. However, the generation of the 4mA offset occurs at the end of the signal path within the sensor circuit. If an error (bad solder joint, component failure, etc.) occurs before the offset generation within the circuit, this may not be detected.


This is where the self-test input of our vibration sensor BVS420 comes in:


If the input is connected to GND potential, the self-test input of the internal sensor element is used to generate a vibration signal at its output. This signal passes through the entire circuit up to the 4...20mA output as well as a mechanical vibration signal. This tests the entire sensor for its function and the current output goes above 20mA as long as the self-test is activated. This current signal, which is higher than the full scale value of the sensor, can be used to test the switching thresholds of external monitoring devices, as well as associated delay times. Thus, the error-free operation of the entire vibration monitoring chain is checked.


Carried out at regular intervals, this leads to greatest possible security when monitoring high-quality machines and systems.


Measurand: Vibration velocity
Measuring ranges: 0...16mm/s or
Frequency range: 10...1000Hz / -3dB
  (Butterworth 4. Order)
Measurement accuracy: +/- 5%
Non linearity: +/- 2%
Transverse sensitivity: < 5%
Supply voltage: 24V (12...28V) DC
Current output: 4...20mA
Housing material: Stainless steel V2A
Thread hole: M8 x 8 mm
Mounting torque: 8 Nm
Protection grade: IP67
Ambient temperature: -20...+70 °C
Dimensions (D x L): 29,6 x 62 mm
Hexagonal base: WS30
Weight: appx. 150g




BVS420 - Vibration sensor with self-test
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