Introduction; Calibration Overview; Calibration Interval And Performance; Calibration Points - Fluke 8508A User Manual

Introduction

Chapter 7 describes the calibration menus, and lists the calibration and performance
verification procedures for the 8508A Reference Multimeter. Remote commands for
calibration of the 8508A are described in Chapter 4 Remote Operations using the
IEEE 488 Interface. In this chapter menu and button selections are shown as all-caps text.

Calibration Overview

The 8508A is calibrated via an electronic autocal feature which allows full calibration of
all functions from the front panel (or remotely via the IEEE 488.2 Interface). No
hardware adjustments are required.
For each combination of function and range, an appropriate calibration standard (source)
is input. At each setting, one keystroke immediately calibrates to the standard by
updating an internal non-volatile calibration memory. The instrument automatically
determines whether the operation is to be a Zero or Range Gain calibration; or for AC
ranges whether it is to be a Zero, LF Gain or HF Gain calibration. As part of the
calibration procedure, a non-volatile input-offset compensation is adjusted independently
for the front and rear inputs. The autocal process can operate only when the rear panel
Calibration switch is in the 'Enable' position. Applying an integrity seal or calibration
sticker to prevent access to the rear panel Calibration switch is a convenient way to
ensure the security of calibration. When a calibration operation is performed the 8508A
internal calibration memory is immediately updated. It is possible to calibrate a single
range or single point if the user chooses to do so. However, it is recommended that the
calibration procedure listed later in this chapter be followed closely.

Calibration Interval and Performance

It is recommended that the 8508A be calibrated on either a 365-day or 90-day interval
depending on the requirements of the applications for which the 8508A is used and the
performance specifications required. The performance of the 8508A is specified for
periods of 365 days and 90 days – if recalibration takes place on a 90-day cycle use the
90-day specifications for improved performance.
During manufacture, the 8508A is calibrated with low uncertainties, reflected in the
Absolute Specifications listed in Chapter 5 Specification section. After recalibration, the
user should apply the calibration uncertainties for the calibration standards and for the
process applicable to that calibration by combining those calibration uncertainties with
the 8508A Relative to Standards specifications, as described in Chapter 5.
Many 8508A owners prefer using Fluke calibration services instead of maintaining their
own standards to support their 8508A.To help ensure optimum performance from the
8508A, Fluke offers our calibration service at a variety of worldwide locations. Our
worldwide service network provides fast efficient calibration to ensure low uncertainties
and optimum accuracy consistent with the original calibration at manufacture.

Calibration Points

There is generally more than one calibration point for each range. An initial measurement
(made when the calibration is triggered) determines the intended calibration point. The
points for each range and function are listed later in this chapter.
Calibration and Verification

Introduction

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