Equipment Requirements; Interconnections; Applicable Verification Tolerance And Conditions - Fluke 8508A User Manual

Equipment Requirements

The equipment required for performance verification of the 8508A is identical to the
equipment required for routine calibration listed in Table 6-1. 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 8508A, the 5720A, and the 5725A for the
purpose of 8508A 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 8508A 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 and 20 G resistance ranges the 1 G standard resistor
supplied in the Fluke 8508A-7000K Calibration kit plugs directly into the 8508A 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 8508A 365 day
Tcal 1 C 99 % Confidence Level Absolute specifications, which include contributions
for the performance of the 8508A itself and the uncertainty of the calibration standards
used to perform calibration adjustment of the 8508A 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 8508A 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 8508A
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 8508A temperature coefficient specifications should also be applied if the
temperature at verification is outside the range applicable to the 8508A specifications to
be used.
Refer to Chapter 5 for further information on applying specifications and combining
uncertainties.
Note that the tolerance testing is done with 7-digit resolution for speed and efficiency
reasons. However, the tolerance limits are based on the tighter specifications of 8-digit
measurement resolution. (The minor tolerance adders for the reduced resolution are
disregarded as practically insignificant in most cases. These adders apply to DC volts,
Calibration and Verification
Performance Verification
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