US Patent 8115474 Multi-range electrical current measurement

An electrical current measurement system. A first low-range current gauge receives a current to be measured and provides a first intermediate value indicative of the amplitude of the current up to a first maximum current. A second low-range current gauge receives any portion of the current having a magnitude that exceeds the first maximum current and provides a second preliminary value indicative of the amplitude of the portion of the current having a magnitude that exceeds the first maximum current up to a second maximum current. An arithmetic unit or a digital processor receives the first intermediate value and the second preliminary value and provides a second intermediate value indicative of the amplitude of the current. A full-range current gauge may also be provided. A selector or the digital processor selects one of the values for display or other output.