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Curran919

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I'm helping one of our factories with a spec on combining two existing DAQ systems.

I'm having some trouble with the Bently Nevada 330400 Accelerometers. They have a 3-wire connector, but are apparently also IEPE? What is that third wire doing?

OLi

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Can it be temperature? I don't know specific but there are other brands with IEPE where the 3d pin is temperature.
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fburgos

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0volt, -24volt and signal, this was the old sckecnk vt41 had its accelerometers
Curran919

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but ferdy, these sensors operate with a bias voltage and a 2mA constant bias current. They do not need VDC excitation.
Walt Strong

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https://www.bakerhughesds.com/sites/g/files/cozyhq596/files/2019-06/330400%20and%20330425%20Accelerometer%20Acceleration%20Transducers%20Datasheet%20-%20141638.pdf

Stock cable: 

Red = Power (-24 V)

Black = COM

White = Signal (Bias voltage -8.5 Vdc)

Walt

fburgos

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Reply with quote  #6 
I'm not good with electronics and signals, I just remember I can't use the vt41 accelerometer (3 wire, 0 volts, -24 and one for the signal) with newer vt60 (2 wire tnc) technical difference or why is out of my knowledge
OLi

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It could have been this     https://www.ctconline.com/dual_output_accelerometers_w_temperature_output.aspx?prd=TA102

If it is a Bently, those I have seen recently are standard 2 pin IEPE but I guess there are like these maybe around? "Negative voltage sensor" most likely I guess and similar to:
https://www.ctconline.com/ctc_100_mv_g_standard_size_accelerometers.aspx?prd=AC165


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Sinski

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Quote:
Originally Posted by OLi
It could have been this     https://www.ctconline.com/dual_output_accelerometers_w_temperature_output.aspx?prd=TA102

I
f it is a Bently, those I have seen recently are standard 2 pin IEPE but I guess there are like these maybe around? "Negative voltage sensor" most likely I guess and similar to:
https://www.ctconline.com/ctc_100_mv_g_standard_size_accelerometers.aspx?prd=AC165


Oli

It is the AC165. We had some of those 330400 sensors on our old turbine and the AC165 was the direct replacement.
Walt Strong

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In case you are still looking for wiring diagram. Following on Sinski's post:

https://www.ctconline.com/epicor/Wiring_Negative_Voltage.pdf

Walt
Curran919

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I see a similar sensor, the B&K AS-020 also has the 3 wire config, but has a better spec sheet and shows it as a typical 3-wire sensor with insignificant current on the signal wire.

I guess I'll just assume that BN's 2mA bias current is not a bias current in the 2-wire IEPE sense, but just a typical current on the -24V wire.
fburgos

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Quote:
Originally Posted by Curran919
I see a similar sensor, the B&K AS-020 also has the 3 wire config, but has a better spec sheet and shows it as a typical 3-wire sensor with insignificant current on the signal wire.

I guess I'll just assume that BN's 2mA bias current is not a bias current in the 2-wire IEPE sense, but just a typical current on the -24V wire.


thats the one the old schenck vp41 use.
Sinski

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Quote:
Originally Posted by fburgos


thats the one the old schenck vp41 use.

We had a Schenck system on our turbine and I believe they were the sensors as well.
John from PA

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Reply with quote  #13 
The attached are graphics from the 330400/330425 User's Guide and may be helpful.  The transducer is normally used with an API monitor which has OK check circuitry, hence the need for the 3rd pin and a -8.5 vDC bias voltage.  The black and red terminations carry the typical -8.5 vDC bias and an AC signal proportional to the acceleration, typically at a scale factor of 100 mV/g.  


 
Attached Files
pdf 330400_330425.pdf (275.95 KB, 10 views)

Curran919

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Reply with quote  #14 
Quote:
Originally Posted by John from PA
... API monitor which has OK check circuitry...


Aaah, this brings it all together. Cheers John.
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