High-pass filter for enhancing the resolution of AC power line harmonic measurements

An instrument employs a high-pass filter and an associated amplifier to reduce the number of Analog-to-Digital-Converter bits required to determine the amplitude of harmonics contained in digitally sampled AC (alternating current) power system voltage or current waveforms. The instrument is coupled to a power system having a line conductor and a neutral conductor for obtaining time-domain representations of the current flowing in the line conductor and the voltage difference between the line conductor and the neutral conductor. The time-domain representations are converted to frequency-domain representations by a single-chip microprocessor.