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Noknroll

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Reply with quote  #16 
Got it, thanks
John from PA

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Reply with quote  #17 
Quote:
Originally Posted by Noknroll
Got it, thanks


Suggestion: summarize it and post the content.  There is very little good info on the web on how to do accomplish the task.  One old thread makes reference to a CSI Technote but unfortunately the link is broken.
Shoveldr

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Reply with quote  #18 
Also make sure you are using a volts input adapter as opposed to an accelerometer one.
fburgos

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Reply with quote  #19 
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Originally Posted by John from PA
As others have said, connect to the buffered output of the monitor and make sure your transducer power is off.  I underlined "output" to emphasize the BNC connector has everything you need; nothing needs to come from the CSI box.  The scale factor, as others have pointed out is most likely 200 mv/mil or 7.87 mv/micrometer for proximity probes.  Keep in mind that the BN rack is also usually using a peak detector and CSI depending on your setup uses an RMS detector scaled to peak so readings may not match, but should be within 25% to 30% depending on frequency content.  

Keep in mind as well that the BN buffered output has a DC bias voltage that is typically around -10 vDC.  You might have to do something like AC couple the 2130 so the -10 vDC doesn't drive your full scale on the 2130.

If the desire is to get near the reading of the monitor, you might also have to bump up the Fmax to see the range of frequencies that the monitor may be seeing.


Can I ask in this thread about 2140?

What's the difference between AC couple and DC couple, I was doing some testing and find out phase measurement are different...

Attached Images
jpeg 20190704_072958.jpg (148.59 KB, 15 views)
jpeg 20190704_072916.jpg (129.73 KB, 15 views)

John from PA

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Reply with quote  #20 
AC coupling uses a capacitor to filter out the DC signal component from a signal with both AC and DC components.  The capacitor is in series with respect to the signal. AC coupling is useful because the DC component of a signal acts as a voltage offset, and removing it from the signal can increase the resolution of signal measurements.  A BN/GE proximity probe for instance has a DC bias voltage of approximately -10 vDC and an AC component "riding" the DC at 200 mV/mil.  By blocking the DC component, the resolution of the measuring device can be adjusted to best view the AC component, likely very small as compared to the DC component.

DC coupling allows both AC and DC signals to pass through a connection since there isn't a series capacitor.  Usually DC coupling is used on signals with both DC and AC levels that are low.

The phase shift occurs due to the capacitor and is normal.  Your attached graphics seem to be at 3600 RPM (60 Hz) but it isn't clear to me which (if any) is AC or DC coupled.  Normally, if the signal is predominately 60 Hz, the phase shift difference should be very small.
fburgos

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Reply with quote  #21 
Thanks for the explanation John.

Can't remember what picture is AC/DC [cool],

took them at the same "time" only changing that parameter in the sensor setting 

now that i look not only the phase is different the amplitud is also different.

i'll do some more test this week and report back.
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