VirtualBench

[Geophysics]

Hi all,

I recently decided to use my NI 4351 DAQ board with the TBX-68T terminal block for simple voltage measurements - the problem is that I detect a huge grounding problem (at least 2.5v) - when I connect the terminal block to my experimental column I get a couple of minutes correct measurements but then the charge starts to build up -
If I connect any channel to anything that is grounded - the charge diminished rapidly
I tried all the options on virtual bench - checked ground reference on, and off - doesn't make any difference
My experimental columns cannot be grounded.
I checked 2 different boards and 2 different terminal block on 2 different pcs - the same problems
Any solution to avoid the grounding errors?

thank you,

Dimitris

[Travis_W]

Hi Dimitris,

For measuring signal sources that are not grounded, it is recommended to provide a resistive path to ground on the signal wires.  This will allow any additional charge that builds up to be immediately dissapated.

Please refer to this tutorial for further information on correcting the issue.  Also, please post again with the results, as we want to make sure you get this problem resolved.

Have a great day!
Travis W

Message Edited by Travis W on 09-28-2006 10:07 AM