b)
Calculate the lower and upper current measurement test limits using the following
formula: Current Measurement Test Limits = Test Point ± (|Test Point| * % of
C Offset ).
c)
Verify the DMM measurement falls within the test limits.
7.
Repeat the previous steps, from setting the level to the test point on the NI 4138 up to this
step, for each specified test point in the level range.
8.
If more than one level range is specified, repeat the previous steps using the values
specified in each level range.
Verifying 1 A and 3 A Current Measurement and Output
Compare a set of currents measured by an external DMM to the current test points requested
by the NI 4138.
Complete this procedure only after successfully completing all previous verification
procedures. Verify ranges in the specified order.
Refer to the following table as you complete the following steps.
Table 8.
1 A and 3 A Current Output and Measurement Verification
Level
Range
Limit
Range and
Limit
Shunt
Test
Point
As-Found
Measurement Test
Limit (% of Current
+ Offset)
As-Left
Measurement Test
Limit (% of Current
+ Offset)
1 A
6 V
1 Ω
-1 A
0.03% + 120 μA
0.013% + 15 μA
1 A
3 A
6 V
333 mΩ
-3 A
0.06% + 1.8 mA
0.045% + 500 μA
3 A
1.
Make the necessary connections for this procedure, as shown in the following figure.
Figure 8.
Current Verification Connection Diagram
NI-DCPower Device
Sense LO
Sense HI
HI
LO
+
–
Precision
Shunt
DMM
Voltage
Mode
14
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NI PXIe-4138 Calibration Procedure