Electrically isolated approach to sensing dc voltages referenced to a

Abstract

An analog isolation barrier data acquisition system comprises a plurality of satellite sampling modules which are referenced to remote grounds for sensing direct current (dc) voltages which are referenced to these remote grounds. The satellite sampling modules are capable of monitoring several signals which are referenced to its local ground system, and are comprised of three functional blocks: a signal selection block which allows proper selection of the dc voltage signal to be monitored; a modulation block which modulates the selected dc voltage signal to produce a modulated waveform; and a barrier coupling block which transfers waveform information contained in the modulated waveform from the local floating ground reference system to an analog ground reference system. A central control module, coupled to each of the satellite sampling modules and referenced to the analog ground system, is comprised of three functional blocks: a waveform generation block which generates a basis waveform for use by the modulation blocks; a circuit block which demodulates the modulated waveform information produced by the modulation block of each satellite sampling module; and a master control block for generating control logic signals which are based on information received from the basis waveform generation block.