Fluke 8508A, Руководство по обслуживанию

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Calibration and Verification
Introduction
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Introduction
This chapter describes the calibration menus, and lists the calibration and performance
verification procedures for the Multimeter. Remote commands for calibration of the
Multimeter are described in Chapter 4 of the Users Manual, Remote Operations using the
IEEE 488 Interface. In this chapter, menu and button selections are shown as all-caps
text.
Calibration Overview
An electronic autocal feature allows full calibration of all functions of the Multimeter
from the front panel (or remotely via the IEEE 488.2 Interface). No hardware adjustments
are necessary.
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 Multimeter 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
Multimeter’s 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 Multimeter be calibrated on either a 365-day or 90-day
interval depending on the requirements of the applications for which the Multimeter is
used and the performance specifications required. The performance of the Multimeter 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 Multimeter is calibrated with low uncertainties, reflected in the
Absolute Specifications listed in Chapter 1 Introduction and Specifications. 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 Multimeter Relative to Standards specifications, as described in
Chapter 1.
Many Multimeter owners prefer using Fluke calibration services instead of maintaining
their own standards to support their Multimeter.To help ensure optimum performance
from the Multimeter, 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.