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Measuring Electrical Resistance Using a SCC 2345 Carrier With SCC-FT01 Panels

Hello,

 

I would like to perform a simple 4-wire electrical resistance test (Kelvin Test). I have availible a SCC 2345 carrier, two SCC-FT01 panels, a SCC-AI05 panel and Signal Express. So what I need is a known excitation current and to be able to measure the voltage accross an unknown resistance. The only way I can think of doing this is to use the J17 and J18 connectors to supply to known current since they are for analog-output connectors, and use a SCC-AI05 to measure the voltage across the unknown resistance. The problem is that I'm not sure how to set this up in Signal Express. There is the option to do a 4-point resistance test, but it only requires one channel to do so. This is confusing because I would think you need 2 channels (AO and AI) to do a 4 point test. My question is given the materials at hand, is there a a way to set-up the hardware so that signal express can record resistance directly or do I need to record AO /AI simultaneously  and use R=V/I to get the resistance? Thanks for any help.

 

modey3

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I've found the best way to do this kind of stuff is to set up and measure manually, then try to duplicate that programmatically.

Bill
CLD
(Mid-Level minion.)
My support system ensures that I don't look totally incompetent.
Proud to say that I've progressed beyond knowing just enough to be dangerous. I now know enough to know that I have no clue about anything at all.
Humble author of the CLAD Nugget.
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Hi modey,

 

Are you using a PCI data acquisition card with this application?  What is the SCC-2345 connecting to?  I'm having some trouble understanding exactly how the hardware pieces you've listed will fit together in the application.  That said, the AO can output current using the SCC-CO20.  Then you would have a known excitation current, and based on what sensing options are available could detect either resistance or voltage.  I think that the most straightforward option for implementing will be to use a known current and measure voltage, then analyze the results, I'm just not 100% that you have all the hardware needed to make that happen yet.

 

Regards,

 

-Dave C

Applications Engineer
National Instruments
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The DAQ device is a PCI-6289 card.

 

Can you use Signal Express to output a known current while simultaneously measuring a voltage drop, or is this something that's going to need to be programmed? What's confusing me is that Signal Express has the option to measure resistance using the 4 wire method, but it's not clear on how to set up the hardware to do this.

 

modey3

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Hi modey,

 

That should be something that can be handled in Signal Express with the right hardware.  Unfortunately, the 6289 does not directly output a constant current, only constant voltages, so I don't know that we'll be able to use this card for the test as described.  You may be able to experiment with outputting a constant voltage and measuring the current from the card.  I also want to verify that you've used these devices together with successful connections.  The accessories say that they work with E series cards specifically, but the PCI card is from our M series.

 

Regards,

 

-Dave C

Applications Engineer
National Instruments
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