Service manual

Test Accuracy
Ratio (TAR)
Definition
Test Accuracy Ratio (TAR) is the ratio of multimeter accuracy to
measurement uncertainty. For the Agilent E1326B multimeter
performance tests, test accuracy ratio = (High Limit value - Test Input
value)/
Measurement Uncertainty value. This value is shown in the "Test
Accuracy Ratio (TAR)" column of Table 4-1.
NOTE
Test accuracy ratio does not apply to the DC Voltage (Zero Volts Input)
test, since no measurement uncertainty value applies.
Multimeter
Accuracy
Calculations
For the Agilent E1326B multimeter performance verification tests,
multimeter accuracy is defined for DC Voltage, AC Voltage, and 4-Wire
Resistance measurements using the 90-day specifications in Appendix A
- Specifications of the Agilent E1326B/E1411B User’s Manual. The
assumed test conditions are:
• One year since the last calibration
• Temperature within ± 5
o
C of calibration temperature
• Module calibration temperature 18
o
C to 28
o
C
• One hour warmup
• 4-wire ohms resistance measurements
• Aperture = 16.7 msec (60 Hz) or 20 msec (50 Hz)
• Autozero ON
DC Voltage
Accuracy
Equations
From Appendix A of the Agilent E1326B /E1411B User’s Manual, DC
voltage 1-year accuracy = ± (% of reading + volts). The accuracy
equations for the ranges and apertures used in the performance
verification tests are:
Range
Accuracy [± (% of reading + Volts)]
125 mV
1 V
8 V
64 V
300 V
0.023 + 5.0 µV
0.013 + 15.0 µV
0.010 + 50.0 µV
0.015 + 1.0 mV
0.015 + 5.0 mV
Example: Calculate DC Voltage Accuracy
For a 7.0 DCV input to the multimeter, using the 8 V range and 16.7/20
msec aperture, multimeter accuracy (1-year) = ± (.020% reading + 50.0
µV) = ± (.0002 x 7.0 + 50 x 10
-6
) = ± 0.0014 Volts. Thus, for a 7.0 DCV
A-2 Calculating Multimeter Accuracy