Abstract: In data logging applications, a method and apparatus are disclosed for storing an increasing number of consecutive real-time data points, such as those descriptive of AC (alternating current) power line parameters, in a fixed amount of memory by periodically applying a novel compression technique. The compression technique preserves time relationships in the data while maximizing the level of detail consistent with a limited amount of memory. When the memory is full each data point stored is paired with another data point and one value is calculated that will represent the pair of data points, reducing the necessary memory to half and allowing more data points to be stored.
Abstract: An apparatus and method for characterizing an alternating current power line which uses a library of waveforms and associated spectra of digitally sampled alternating current power system voltage or current waveforms. The library of waveforms is built as new waveforms are measured from the alternating current power line. A measured waveform that is not found in the library will be converted to frequency-domain representation, using a Discrete Fourier Transform, that will then be stored in the library. When the library becomes full, the frequency domain representation of the new waveform will be stored in place of the least used waveform currently stored in the library.
Abstract: A stand-alone electronic measuring instrument for measuring AC (alternate current) power parameters on a utility distribution system wherein the measurement results are communicated telephonically to a facsimile device. Well-known techniques are used to acquire and accumulate analog signals representative of voltages and currents on an AC power system and digital signals. If the signals exceed a programmed threshold, or if an interval of time elapses, or if some other triggering even occurs, the instrument prepares a bit-mapped digital report on its accumulated input signals which may contain text, graphics, or both. The instrument then employs well-known techniques to telephonically transmit this report directly to a facsimile receiver without employing an intervening computer system.
June 22, 1992
Date of Patent:
April 18, 1995
Basic Measuring Instruments, Inc.
Alexander McEachern, Scott C. Terry, Jamie Nicholson, Erich W. Gunther
Abstract: An electric power measuring system wherein power factor measurements are adjusted to reflect the adverse economic effects of harmonic currents and voltages. Well-known techniques are used to acquire frequency spectra that represent the voltages and currents present at the measuring point. These spectra are weighted in such a way that non-fundamental currents are increased and non-fundamental voltages are decreased. The weighted spectra are used to calculate a harmonic-adjusted volt-ampere measurement, which is then accumulated to form a harmonic-adjusted volt-ampere-hour measurement. The weighting functions for voltage and current are selected to approximate the economic impact on the AC power generating, transmission, and distribution system of non-fundamental currents and voltages. The resulting harmonic-adjusted volt-ampere-hour measurement is used to calculate a harmonic-adjusted power factor measurement.