tarnishes the copper plugs so that they appear dull rather than shiny and leads to greater
thermal EMF.
•
Prevent the cables from moving or vibrating by taping or strapping them to a
nonvibrating surface. Movement or vibration causes triboelectric effects that can result in
measurement errors.
As-Found and As-Left Limits
The
as-found limits
are the published 2-year specifications for the device. NI uses these limits
to determine whether the device meets the device specifications when it is received for
calibration.
The
as-left limits
are based on the published 24-hour specifications for the device, with
consideration for measurement uncertainty. NI uses these limits to determine whether the
device will meet the device specifications over its calibration interval.
Where a TUR of less than 4:1 was determined, a guardband technique was applied to the test
limits to maintain the same Probability of False Accepts (PFA) as if it was 4:1. The method
selected was the ANSI/NCSL Z540.3 method 6: Guard Bands Based on Test Uncertainty
Ratio.
Verification
The performance verification procedures assume that adequate traceable uncertainties are
available for the calibration references.
You can use the verification procedures described in this section for both pre-adjustment and
post-adjustment verification. You can omit sections (for example, the
Verifying AC Current
section), however, any function not verified during post-adjustment will no longer be traceable
and should not be used for measurements.
Note
Self-calibrate the PXIe-4080/4082 before performing verification procedures.
Verifying DC Voltage
Complete the following steps to verify DC voltage:
1.
Plug in the shorting bar across the HI and LO terminals on the PXIe-4080/4082.
2.
Wait two minutes for thermal EMF to stabilize.
3.
Reset the PXIe-4080/4082.
4.
Initialize the PXIe-4080/4082 for DC Voltage with a range of 100 mV and resolution of
6.5 digits.
5.
Verify the accuracy for each configuration in the following table:
a)
Acquire the measurement at each specified range and input resistance.
b)
Compare to the specified limits.
PXIe-4080/4082 Calibration Procedure
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© National Instruments
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