VFD Bearing Condition Monitoring (Variable-frequency drives)

Variable-frequency drives (VFD) and Bearing Condition Measurement

Many machines are powered by VFD. It means variable frequency drives. These drives generate strong noise on high frequencies. The bearing condition we also measure on high frequencies. The high frequency noise from variable frequency drives makes bearing condition measurement almost impossible. But we have the solution.

We have developed in our laboratories the mathematic procedure which can remove the VFD noise from the signal. Then bearing signal just remains and we can take the perfect measurement of bearing condition.

The example is better than hundreds of words. Now you can hear the signal with VDF noise. And now you can hear the signal, from which the VFD noise was removed. Try to listen now. We switch the procedure for VFD noise removing on and off. It is perfectly clear what the procedure does with the signal. You can you hear a stronger signal with VFD noise and a weaker signal without VFD noise

The g-overall RMS value from 500 Hz to 25 kHz is 3g and the VFD bearing RMS value is only 1.1 g . The VFD bearing value is always RMS.

If this machine would not be powered by VFD the also the g-overall RMS would be around 1.1g.

The next information is for more curious people. The VFD noise removing procedure is not filtering. It is much more complicated.

The VA5 contains this new procedure now. Download the new firmware version from our website and use it.