How to validate the vibration results of BFA001V1B?

[kumarnaveenb]

Hi,

I connected the BFA01V1B and running condition monitoring code. My settings are

 Accelerometer parameters are:

   HpfCut =3   Acc_Odr=6660   FifoOdr=6660   Acc_Fs =16   

MotionSP parameters:

   size=2048   tau=50   wind=1   tdtype=0   tacq=5000   

MotionSP Vibration Initialization

MotionSP Parameters are:

   FFT size: 2048

   FFT ovl : 75%

   Tacq   : 5000 ms

Update Accelerometer Settings:

   Ok Enable HP Filter

   Ok FullScale Setting

   Ok Set Output Data Rate

   Ok measure and calculate ODR

   ODR = 6582.00 Hz

   OK Set Accelerometer Parameters

   Ok Bypass FIFO

The Results are:

   *************************************************************

   *** Time domain speed (RMS) as last value ***

   Speed RMS on X axis was  1.757 mm/s

   Speed RMS on Y axis was  4.566 mm/s

   Speed RMS on Z axis was  1.914 mm/s

   *** Time domain peaks ***

   Max peak on X axis was  9.801 m/s2

   Max peak on Y axis was 17.204 m/s2

   Max peak on Z axis was 12.270 m/s2

   *** Frequency domain results ***

   FFT average for all axes has been performed on 93 items

   FFT max amplitude on X axis was   1.827 m/s2 @  298.89 Hz

   FFT max amplitude on Y axis was   4.561 m/s2 @  298.89 Hz

   FFT max amplitude on Z axis was   3.181 m/s2 @  298.89 Hz

My questions are:

How to calculate RPM. If I consider 299Hz then my RPM = 17940. I dont think my motor is running with this speed.

What I am missing in calculation of RPM.

Normally which axes to be considered to calculate the frequency?

I see pretty consistent signal. I have attached few plots. Is it ok to get this level of consistency.

What are the normal practice to do vibration analysis?

Thanks,

kumar

[Eleon BORLINI · Accepted solution]

Hi kumar @NK.1umar Byregowda​ ,

well yes, 299Hz means 299 x 60 RPM, if the 299Hz is actually if 1st harmonic of the running motor, and if the FFT is correctly calculated (this is the task of the official tool, so I believe it is correct).

Can you please change the ODR settings of the accelerometer and see if you get the same 1st harmonic frequency? And did you try to acquire the acceleration raw data and run the FFT in post processing?

-Eleon

[kumarnaveenb]

Thanks Eleon.

I tried with different ODR. The results are great.

Kumar.