Cannot measure AC current using NI VirtualBench - NI VB-8012

[ArtB83]

Hi All,

I’m trying to perform manual AC current measurements, but a result is just a noise.

I have a simple series circuit with FGEN, as VirtualBench, and load resistor of 50[Ohm]. My measuring setup is as described in the attached image. Except the batteries – I use fGEN at frequency of 486kHZ.

I’m pretty sure that my measuring setup is correct, because when I switch to DC mode – I have a comprehensive current measurements. In addition, when running in AC mode, through the AC multi meter connection, the load resistor is warming up – which means that there is a current in my circuit.

Both fuses were tested for continuity – and were fine.

What do I miss here? Is there some kind of “reset” for the virtual bench?

Thanks in advance

Art

[JoeFriedchicken · Accepted solution]

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ArtB83 wrote:

I’m trying to perform manual AC current measurements, but a result is just a noise.

I have a simple series circuit with FGEN, as VirtualBench, and load resistor of 50[Ohm]. My measuring setup is as described in the attached image. Except the batteries – I use fGEN at frequency of 486 kHz.

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I'm not an analog engineer, but I hypothesize that this circuit's frequency is beyond what the VirtualBench DMM can measure.

Looking that the specs, it appears that the DMM has guaranteed accuracy for AC signals up to 5 kHz:

If you reduce your circuit's frequency to 5 kHz or lower, do you see good measurements?

[ArtB83]

Hi Joe, 

You were 100% right - When I dropped my work frequency to 5kHz - the ampere-meter started to show correct values. 

Thank you very much.

Art