Why Does My PXI-4110 Fail Current Output CalibrationPrimary Software: Calibration ExecutivePrimary Software Version: 1.0 Primary Software Fixed Version: N/A Secondary Software: N/A Hardware: Modular Instruments>>Power Supplies>>PXI-4110
Problem: My PXI-4110 DC Power Supply is failing the Ch 0 Current Output 1A test portion of the 4110 calibration procedure. I am using a DMM that meets the requirements of the calibration procedure, but not the PXI-4071. What is causing this and how can I fix it? Solution: This issue results from using a DMM with a burden voltage that is too large for the calibration procedure. The recommended DMM for 4110 calibration is the PXI-4071, which has a burden voltage less than 250mV at the 1A measurement range. However, many common DMMs that meet the recommended specifications for calibration have a higher burden voltage. When the DMM is added to the calibration system, a burden voltage inherent to the DMM is also added as shown below.
For example, the Agilent 3458A meets the specifications for accuracy and resolution, but has a burden voltage <1.5V. Therefore, it's possible that this additional burden voltage will bring the system voltage drop to 5V before the 1A current limit was reached. The calibration procedure assumes that the 1A limit is reached and thus the 4110 will fail the calibration, even though it may not actually be out of calibration. The work-around to fix this is to use a 3 ohm equivalent resistance instead of the instructed 4 ohms. A future version of the calibration procedure for the 4110 will address this issue. Related Links: Product Manual: NI PXI-4071 Specifications (Sept. 2008) Product Manual: NI PXI-4110 Calibration Procedure Nov. (2008) Attachments:  4110 Calibration Schematic.jpg
Report Date: 04/16/2009 Last Updated: 04/24/2009 Document ID: 4WFE8TZL |
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