Operations Overview; Measurement Principle; Internal Reference Set; Output Stage - Radian RD-30 Operation Manual

Operations Overview

4.0 Operations Overview
4.1 Measurement Principle
The measurement principle is based upon the fundamentals of a high-speed charge-balance
integrating analog to digital signal converter. This is a Radian innovation, but it is based upon
accepted metrology parameters. Radian Research implemented its own analog to digital converter
in the Dytronic family of standards which are specifically designed for power measurement. In order
to measure power and energy with extreme accuracy and wide bandwidth, extensive requirements
must be imposed on the converter.
The RD-30 Dytronic utilizes two separate A/D converters. One accepts a current signal and is
linked with two current references. The other accepts a voltage signal and is linked with two voltage
references. These of course are for the analog voltage and current inputs of the RD-30. Both
operate independently to provide the digital signal processor with signals accurate enough to meet
the requirements of a true portable electricity standard.
By designing an analog to digital converter specifically for power and energy measurements,
Radian is able to reduce many errors associated with commercial A/D circuits. Gain error,
charge timer resolution, signal to noise ratio and signal distortion were major areas dealt with and
improved in development.
4.2 Internal Reference Set
The RD-30's internal reference set is hermetically sealed in order to protect it from environmental
variables. The internal reference set consists of a voltage reference, a resistive reference and a crystal
time reference.
4.3 Output Stage
The RD-30's output stage displays the measurements and provides pulse outputs for the selected
measurements. Computer control, with Radian software, allows for customization of output
information, such as programmable pulse output constants.
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RD-30 Operations Manual