Why Are Capacitance Measurements Inaccurate on the PXIe-4190?

Updated Mar 25, 2025

Reported In

Hardware

  • PXIe-4190

Issue Details

I try to read the capacitance value of a 100nF capacitor using the PXIe-4190, but I only get around 70nF readings in the software. Why is there a 30nF discrepancy in the readings? I tried tuning the LCR frequency, LCR voltage RMS, and LCR measurement time, but the capacitance readings do not change much. Are there any possibilities that incorrect software parameters or configurations could cause an incorrect capacitance measurement of a 100nF capacitor?

Solution

Most capacitors lose capacitance with DC bias. To measure the rated capacitance, set the DC bias to zero. However, the software settings are likely correct, especially since the readings persist across a range of frequencies and excitation levels. Most likely, the 100nF capacitor is not accurate enough. Please verify the capacitance of the 100nF capacitor using another DMM or LCR meter.

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