8508A
Service Manual
3-32
Equipment Requirements
The equipment required for performance verification of the Multimeter is identical to the
equipment required for routine calibration listed in Table 3-1. Alternate equipment may
be used, but users should ensure it provides adequate uncertainties, and consider the
impact of those uncertainties on allowable tolerance limits.
Interconnections
The Fluke 8508A-7000K Calibration kit contains a specially designed lead set which
connects directly to the terminals of the Multimeter, the 5720A, and the 5725A for the
purpose of Multimeter calibration and performance verification. It is recommended that
this lead kit be used to avoid introducing measurement errors due to interconnections and
to duplicate the configuration used by Fluke for Multimeter calibration. A diagram
showing the interconnections used in detail appears in the Routine Calibration section. If
alternate leads are substituted users must ensure they are metrology grade leads, and of
adequate voltage and current rating. Leads should be kept as short as possible,
constructed from low capacitance low leakage dielectric material (PTFE) with low
thermal emf terminations, and exactly duplicate the configuration and interconnections
shown.
When checking the 2 G
Ω
and 20 G
Ω
resistance ranges the 1 G
Ω
standard resistor
supplied in the Fluke 8508A-7000K Calibration kit plugs directly into the Multimeter’s
front input terminals without any interconnecting leads. If alternate resistance standards
are used for verifying performance of the resistance function, refer to the resistance
measurements section of Chapter 3
Making Measurements
for connection details.
Applicable Verification Tolerance and Conditions
The tolerances* listed in this verification procedure are derived from the Multimeter’s
365 day Tcal
±
1
°
C 99 % Confidence Level Absolute specifications, which include
contributions for the performance of the Multimeter itself and the uncertainty of the
calibration standards used to perform calibration adjustment of the Multimeter at the
Fluke factory. They are applicable to a verification performed within a period of 365 days
from calibration and at a temperature within
±
1
°
C of the temperature at which
calibration was performed (23
°
C for calibrations performed by Fluke). It is
recommended that these tolerances only be used for verification of the Multimeter
following calibration by Fluke, and if the above time period and temperature conditions
are met. No allowance has been made for the uncertainty of the equipment used for
verification. If the required conditions are met but the temperature lies within
±
5
°
C of
factory calibration, it is recommended that the user applies the 365 day Tcal
±
5
°
C
Absolute specifications instead.
For other circumstances, such as following calibration by another laboratory, it is
recommended that the user derive verification tolerances* from the applicable
Multimeter’s 99 % Confidence Level Relative to Standards specifications (90 day or 365
day) combined with the calibration uncertainties applicable to the previous calibration.
(RSS summation is recommended, with calibration uncertainties also expressed at 99 %
confidence level).
The Multimeter’s temperature coefficient specifications should also be applied if the
temperature at verification is outside the range applicable to the Multimeter’s
specifications.
Refer to Chapter 1 for further information on applying specifications and combining
uncertainties.
Summary of Contents for 8508A
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