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Calibrating Precision Multimeters Using a Characterized Multifunction
Calibrator
Speaker/Author: Gary Bennett
Fluke Corporation
PO Box 9090
Everett, WA 98206
Phone: (425) 446-6365; FAX: (425) 446-5649
Email: [email protected]
1. Abstract
Can a multifunction calibrator really verify a long scale digital multimeter that is more accurate
than the calibrator? This paper describes methods to characterize a multifunction calibrator to
better than manufacturer's 24 hour specification at all points that are used to verify 8.5 digit
multimeters. Using automated processes, data collection and statistical methods, it was found
that a calibrator can be characterized at all required values to uncertainties capable of verifying
long scale DMMs. Sources of error that had to be overcome include thermal EMF, loading errors
from the devices used to measure the calibrator output and loading errors from DMMs when
measuring the characterized output. Data from repeated measurements of the calibrator shows 10
V will drift less than 0.3