Current Measurement Accuracy - Keithley 2430 Service Manual

Current measurement accuracy

Follow the steps below to verify that Model 2430 current measurement accuracy is within
specified limits. The procedure involves applying accurate currents from the Model 2430 cur-
rent source and then verifying that Model 2430 current measurements are within required limits.
10μA to 1A range accuracy
1.
2.
3.
4.
NOTE
5.
6.
3A and 10A pulse range accuracy
NOTE
1.
2.
3.
4.
With the power off, connect the digital multimeter to the Model 2430 INPUT/OUTPUT
jacks, as shown in Figure 1-2.
Select the multimeter DC current function.
Set the Model 2430 to both source and measure current by pressing the SOURCE I and
MEAS I keys, and make sure the source output is turned on.
Verify measure current accuracy for the 10μA-1A range currents listed in Table 1-6. For
each measurement:
• Select the correct source range.
• Set the Model 2430 source output to the correct value as measured by the digital mul-
timeter.
• Verify that the Model 2430 current reading is within the limits given in the table.
It may not be possible to set the current source to the specified value. Use the closest
possible setting, and modify reading limits accordingly.
Repeat the procedure for negative calibrator currents with the same magnitudes as those
listed in Table 1-6.
Repeat the entire procedure using the rear panel INPUT/OUTPUT jacks. Be sure to
select the rear panel jacks with the front panel TERMINALS key.
The 1Ω resistor should be characterized to within ±300ppm before verifying the 3A
current measurement range. Use the 4-wire ohms function of the DMM to measure
the resistance value, and then use that measured value to calculate the current during
the measurement procedure. Also note that verification of the 3A range confirms 10A
pulse range accuracy.
With the power off, connect the 1Ω resistor and digital multimeter to the Model 2430
INPUT/OUTPUT jacks, as shown in Figure 1-3.
Select the multimeter DC volts function.
Set the Model 2430 to both source and measure current by pressing the SOURCE I and
MEAS I keys, and make sure the source output is turned on.
Verify measurement current accuracy for the 3A range as follows:
• Select the 3A source range.
Performance Verification 1-13