4
|
ni.com
|
NI 4071 7½-Digit FlexDMM Calibration Procedure
•
Allow the calibrator to settle fully before taking any measurements. Consult the Fluke
5720A user documentation for instructions.
•
Allow the thermal EMF enough time to stabilize when you change connections to the
calibrator or the NI 4071. The suggested time periods are stated where necessary
throughout this document.
•
Keep a shorting bar connected between the
V GUARD
and
GROUND
binding posts of the
calibrator at all times.
•
Clean any oxidation from the banana plugs on the Fluke 5440 cables before plugging them
into the binding posts of the calibrator or the banana plug connectors of the NI 4071.
Oxidation tarnishes the copper banana plugs so that they appear dull rather than shiny and
leads to greater thermal EMF.
•
Keep the blue banana plugs on the Fluke 5440 cables connected to the
V GUARD
binding
post of the calibrator at all times.
•
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.
Calibration Procedures
The calibration process includes the following steps:
1.
—Set up the test equipment.
2.
—Verify the existing operation of the device. This step confirms
whether the device is operating within its specified range prior to calibration. Figure 7 in
Appendix A shows the procedural flow for verification.
3.
—Perform an external adjustment of the device that adjusts the
calibration constants with respect to standards of known values. Figure 8 in Appendix A
shows the procedural flow for adjustment.
4.
Reverification—Repeat the verification procedure to ensure that the device is operating
within its specifications after adjustment.
These steps are described in more detail in the following sections.
Note
In some cases, the complete calibration procedure may not be required. Refer
to
Appendix A: Calibration Options
Throughout the procedure, refer to the C/C++ function call parameters for the
LabVIEW input values.
Initial Setup
Note
This section is necessary only for pre-adjustment verifications. If you are
performing a post-adjustment verification, skip the setup and go directly to the
section.
