Patent ID: 7589516

Claim:
An electric energy meter for poly-phase electricity comprising: a front-end circuit including a first input channel having a first multiplexer having a plurality of inputs, each input connected to a current transformer of a corresponding one of the phases of the poly-phase electricity, an output and a selection input, said first multiplexer selectively connecting one input to said output dependent upon said selection input, a first analog-digital converter having an input connected to said output of said first multiplexer and an output, said first analog-digital converter generating a digital output corresponding to an analog signal at said input, a first de-multiplexer having an input connected to said output of said first analog-to-digital converter, a plurality of outputs and a selection input, said first de-multiplexer connecting said input to one of said outputs dependent upon said selection input, and a plurality of first data registers, each data register connected to a corresponding output of said first de-multiplexer for storing said corresponding de-multiplexer output; a second input channel having a second multiplexer having a plurality of inputs, each input connected to a voltage divider of a corresponding one of the phases of the poly-phase electricity, an output and a selection input, said second multiplexer selectively connecting one input to said output dependent upon said selection input, a second analog-digital converter having an input connected to said output of said second multiplexer and an output, said second analog-digital converter generating a digital output corresponding to an analog signal at said input, a second de-multiplexer having an input connected to said output of said second analog-to-digital converter, a plurality of outputs and a selection input, said second de-multiplexer connecting said input to one of said outputs dependent upon said selection input, and a plurality of second data registers, each data register connected to a corresponding output of said second de-multiplexer for storing said corresponding de-multiplexer output; a multiplexer control connected to said selection inputs of said first and second multiplexers and said first and second de-multiplexers, said multiplexer control supplying said selection inputs of said first and second multiplexers to synchronously select signals corresponding to the same phase of the poly-phase electricity, and said multiplexer control supplying said selection inputs of said first and second de-multiplexers to sequentially store digital samples corresponding to each phase of the poly-phase electricity in corresponding data registers; and a micro-controller operable to access data in said first and second data registers and computer electric power consumed.