Could not acquire voltage waveform with PXi 5112 digitizer

[shareef]

Hi all, I am doing my master degree in Power Electronics. For my academic project, I need to acquire leakage current waveform that flows in the insulator. So we tried to acquire the current using PXI 5112. As it cannot acquire current directly, we went for current to voltage conversion (the leakage current is analog in nature), in such a way that it meets the voltage range of the PXI 5112 oscilloscope. We are using BNC connector recommended by NI. The probe is connected to one of the two channels of PXI 5112 oscilloscope, and once we connect the positive and negative terminal of the probe to the voltage signal terminals, we didn't get the waveform as oscilloscope. Rather, the power supply board from which the PXI instrument,the display monitor, and the supply for insulator, gets cut off, and no power output from that board.We could not find what is the issue. Please do help me and clarify me about the issue, whether it is related to power rating, or problem with probe.

Please help me...

Thank you in advance...

[DFGray]

It sounds like you have a hardware issue.  Unfortunately, such things are very difficult to diagnose in a forum post.  My guess would be that the ground side of the 5112 input is not being connected to a true ground on your electronics, causing a short circuit.  The inputs of the 5112 are not floating.  If you need a floating input, connect your positive lead to one input of the 5112 and your negative to the other.  Subtract the negative result from the positive to get the true signal.  Make sure you DC couple them and at least self-calibrate before doing.  The ground (negative) terminals of the 5112 should be connected to a true ground on your electronics.

A host of other things could also be a problem  I would strongly recommend you find someone locally who knows analog electronics well and get their assistance in debugging your issue.

[shareef]

Thank you for the suggestion...