Each 8B33 True RMS input module provides a single channel of AC input which is converted to its True RMS DC value, filtered, isolated, amplified, and converted to a standard process voltage output (see Block Diagram).
The field voltage or current input signal is processed through a pre-amplifier and RMS converter on the field side of the isolation barrier. The converted DC signal is then chopped by a proprietary chopper circuit and transferred across the transformer isolation barrier, suppressing transmission of common mode spikes and surges. The computer side circuitry reconstructs, filters, and converts the signal to an industry standard output of 0 to 5VDC.
Special input circuits provide protection against accidental connection of power line voltages up to 350VAC and against transient events defined by ANSI/IEEE C37.90.1.
Read our Application Note 101, Measuring RMS Values of Voltage and Current