Operational Verification Tests; Dc Operational Accuracy Test; Test Procedure - HP 3455A Operating And Service Manual

Model 3455A
leading: sheve this paint show that
+ grove is definitely out of specs
OVM spec + std soee
DVM spec - -
OVM spec - std pee —_ — das ot Fs
Readings in thiv r e g i o n guarantee
that DVM is within specs
region are ambiguous
% Error
DVM epee - std spec
'OVM spec
DVM spec + std spec
—_ \ Readings below this paint shaw that
DYM isdefinitely out of specx
3455 -B-4738
Figure 4-1. Ambiguous Regions.
b. If the DVM reading is out of tolerance by a per-
centage that is greater than the maximum allowable error of
the standard, the DVM is definitely outside of its specifica-
tion.
c. If the DVM reading is in or out of tolerance by a per-
centage that is less than the maximum allowable error of
the standard, it is in one of the ambiguous regions (shaded
within its specification and the only way to tell for sure is
to use a more accurate standard.
4-24. As the accuracy specifications of the standard
approach the specifications of the DVM to be tested, the
ambiguous regions shown in Figure 4-1 become wider and
the uncertainty
contributions
of the standard
become
increasingly significant. If the standard is less than three or
four times more accurate than the DVM, the performance
test is not practical because the ambiguous regions cover
most of the DVM's error range. From a practical stand-
point, the de standard should be at least five times more
accurate than the 3455A specifications to be tested. If such
a standard is not available, an alternative approach is to
use a calibrated standard that is extremely stable and (pre-
ferably) two to four times more accurate than the 3455A.
When this is done, the correction
factors given on the
dc standard's calibration chart must be algebraically added
to the 3455A test readings. Test validity depends on the
calibration
uncertainties
and the short-term
stability of
the standard.
4-26. OPERATIONAL VERIFICATION TESTS.
4-27. DC OPERATIONAL ACCURACY TEST.
4-28. The DC Transfer Standard required for the
following test must be calibrated to a 1.017 V to 1.019 V
standard cell that has been calibrated by the National
Bureau of Standards (NBS). If the 3455A is to be tested
for its 24-hour accuracy specifications, the Transfer
Standard must be adjusted for optimum 1-volt and_
Section IV
4-30. Test Procedure.
Equipment Required:
Reference Divider (Fluke Model 750A)
DC Transfer Standard (Fluke Model 731A)
DC Standard (Systron Donner Model M106A)
DC Null Voltmeter (-hp- Model 419A)
a. Set the 3455A controls as follows:
FUNCTION) ssnso eetenstdnses DCV
RANGE
AUTO CAL
GUARD ...........
TRIGGER
b. Set the DC Transfer Standard for an output of 1
V. Connect the output of the transfer standard to the
3455A INPUT.
c. The 3455A reading should be within the test limits
listed in Table 4-1, verifying its 1-volt full-scale accuracy
with High Resolution on.
d. Set the 3455A RANGE to 10 V. The 3455A
reading should be within the test limits listed in Table
4-3, verifying its 10-volt tenth scale accuracy with High
Resolution on.
¢e. Set the Transfer Standard for an output of 10 V.
The 3455A reading should be within the test limits listed
in Table 4-1 verifying its 10-volt full scale accuracy with
High Resolution on.
Table 4-1.
DC Accuracy Test (1 V, 10 V Full Scale; High
24 Hour
Resolution Qn).
90 Day
Test Limits Test Limits
1v lv
0.999966 to 1.000034
9.999936 to 1.000064
10V }10V 9.99977 to 10,00023 9.99947 to 10.00053
_ f£. Set the 3455A HIGH RESOLUTION to OFF. The
3455A reading should be within the test limits listed in
Level | Range
4.3