proximity probe fluctuation with SCXI-1122/SCXI-1322 and Bently-Nevada prox probe

[Ralph@NES]

As the title suggests, I'm getting odd voltage fluctuations from my Bently-Nevada proximity sensor.

I'm trying to use this sensor to measure displacement of a bearing housing when load is applied via a pneumatic cylinder.  The amount could be in the range of .0002-.0005".

I have a calibration stand setup with a depth micrometer and the prox probe.  At operating distance it looks like I have about .7 volts per .001". .07v per .0001.  Pretty good resolution and should be good for reading the displacement.

Unfortunately, when at rest in my calibration stand, I get a voltage fluxuation (seems smooth like a sine wave) of .02v, give or take.  I know that's not a huge amount, but I'm wondering if I can chalk that up to limitations of the sensor, fluctuations in power supply or interference?

If it's a power supply fluxuation, what kind of processing could I do to the power supply to get it normalized?  Any input?

Thanks in advance,

Ralph

[MissyS]

Hi Ralph,

I have some questions to help troubleshoot this issue. Is your measurement single ended or differential? For more information about this, see this tutorial. Do you see this fluctuation if you attach the sensor to a different channel and read from this? Do you also see the same behavior from Measurement & Automation Explorer (MAX)? Do you see the same behavior if you attach a constant voltage source (such as a battery) to the channel?

Regards,

[Ralph@NES]

All good things to check...  Thanks for your input Missy.