Line voltage and line current signals are sensed on a power line having at least one conducting path. The sensed line voltages and line currents are converted into a digital signal. A phase-to-neutral voltage signal and phase current signal are computed from the digital signal to thereby define a phase of the power line. An interval of orthogonality is determined from the sensed voltage and current signals, coinciding with passage of an integral number of cycles of a fundamental frequency reference signal which is computed from the computed phase-to-neutral voltage signal. A vector metering quantity is computed for the determined interval of orthogonality from the computed phase-to-neutral voltage signal and the computed phase current signal. The vector metering quantities to be computed may be identified and computed based upon an associated detent. The vector metering quantity is also computed based on an identified circuit topology.
A disclosed semiconductor integrated circuit device includes a digital circuit and an analog circuit formed on one semiconductor substrate; a guard band configured to prevent noise generated in the digital circuit from being transmitted to the analog circuit; a first power supply terminal configured to supply a power-supply voltage to the analog circuit; a first ground terminal configured to supply a ground potential to the analog circuit; a second power supply terminal configured to supply the power-supply voltage to the digital circuit; a second ground terminal configured to supply the ground potential to the digital circuit; and a filter circuit positioned between the second power supply terminal, the second ground terminal, and the digital circuit and configured to remove the noise transmitted from the digital circuit.
