PCB accelerometer readings

[Handy_Bants]

Hello All,

First time posting a question - I'm looking for some advice regarding accelerometer measurements on a Genset running full load @ 50Hz

I'm using PCB single axis accels and HBM data aquisition kit, and most of my data is fine. I'm able to process to the results using Uniplot.

In some instances I am getting strange results - measurements are subjected to distortion observed on numerous occasions.

I cannot understand where this distortion is coming from - at part loads the measurements are fine. As I hit full load I suddenly get this strange signal distortion. I've attached screenshots of what I consider good and bad data at the bottom:

Really hope that somebody can give me some advice as to what is causing this type of measurement. Any help is greatly appreciated.

Many thanks,

Andy

Screenshots below

[Handy_Bants]

[Dennis_Knutson]

How is your question related to NI signal conditioning hardware or any NI software? This is not a board for general questions on sensors and certainly not a board for hbm software.

[Handy_Bants]

I purchased the accels through the NI website.

I thought I might be able to get some good tips from the 'community' identifying different traits regarding data validation.

Consider myself recalibrated.............

[Dennis_Knutson]

Please provide the details on the accelerometers then. Your original question was entirely generic.

[Henrik_Volkers]

Bad cable / connection ?

If the output of the diagram (with funny scale names 😉 ) is inverted and the sensor is current driven, I vote for shortcuts (about some kOhm) together with the highpass ....

[Handy_Bants]

Hi Henrik,

Thanks for replying. I had to be careful sharing proprietry information which is why I was so vague.

I spent some time after the holidays taking further measurements and using mica washers, applying EMI tape to the cables, grounding engine and kit, changing accels and wiring, without much success.

This lead me to believe that the data I was capturing was being influenced by turbulence / recirculation within the pipework.

I have since proven that it was a bad connection as you suggested, leading me to be extra vigilant when applying the accels to components from now on. However the challenges have greatly improved my understanding interpreting vibration results.

Kind regards,

Andy.