Abstract: A method and apparatus for detecting power quality or disturbance events, such as voltage swells, sags or impulses, in power signals at remote locations of a power distribution system and for conveying information relating to the power disturbances to a central location. Voltage and/or current signals in electric power lines are monitored and converted to low level analog signals. The low level signals are processed by analog processing circuits or are digitally sampled and processed by digital processing circuits to detect power disturbances. Each power disturbance is characterized according to multiple parameters. The characterization information is encoded into a single signal. This is done by assigning a subset of a range of possible values of the signal to represent a parameter and then assigning a value within each subset of the range to represent another parameter.

Abstract: A power supply for an instrument that measures waveforms on AC (alternating current) power systems. Under ordinary circumstances, the power supply draws its power from the signal that the instrument measures. The power supply includes energy storage means. When the instrument must make a precise measurement that could be affected by the power drawn by its power supply, the instrument temporarily disconnects its power supply from the measured signal and draws power from its energy storage means, effectively coasting on the stored energy. At the conclusion of the precise measurement, the instrument reconnects its power supply to the signal being measured.

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.

Abstract: 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.

Abstract: An electric power measuring system wherein the watt-hour measurements are adjusted to account for the 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 used to calculate power flow direction and magnitude at various frequencies. Weighting functions are applied to power flows at frequencies other than the fundamental frequency. The weighted power flow is used to calculate an harmonic-adjusted watt measurement, which is then accumulated to form a harmonic-adjusted watt-hour measurement. The weighting functions can be selected to provide an economic incentive for a power consumer to consume power in a way that matches the goals of the power provider.

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.

Abstract: An instrument for measuring voltage harmonics and current harmonics on AC (alternating current) power systems. The instrument includes the ability to determine when threshold limits have been exceeded for harmonics. The instrument also includes timing thresholds whose inputs are activated when the harmonic thresholds are exceeded. A single harmonic threshold is applied to measurements from multiple phases on poly-phase systems by comparing the square rot of the sum of the squares of measurements from each phase to the harmonic threshold. Three indicators show when voltage harmonic limits are exceeded, current harmonics limits are exceeded, or both voltage and current harmonic limits are exceeded simultaneously.

Abstract: An electric power measuring system wherein the watt-hour measurements are adjusted to account for the 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 used to calculate power flow direction and magnitude at various frequencies. Weighting functions are applied to power flows at frequencies other than the fundamental frequency. The weighted power flow is used to calculate an harmonic-adjusted watt measurement, which is then accumulated to form a harmonic-adjusted watt-hour measurement. The weighting functions can be selected to provide an economic incentive for a power consumer to consume power in a way that matches the goals of the power provider.

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.

Abstract: An instrument for measuring voltage harmonics and current harmonics on AC (alternating current) power systems The instrument includes the ability to determine when threshold limits have been exceeded for harmonics. The instrument also includes timing thresholds whose inputs are activated when the harmonic thresholds are exceeded A single harmonic threshold is applied to measurements from multiple phases on poly-phase systems by comparing the square root of the sum of the squares of measurements from each phase to the harmonic threshold. Three indicators show when voltage harmonic limits are exceeded, current harmonics limits are exceeded, or both voltage and current harmonic limits are exceeded simultaneously.

Abstract: An instrument for measuring voltage harmonics and current harmonics on AC (alternating current) power systems. The instrument includes the ability to determine when threshold limits have been exceeded for harmonics. The instrument also includes timing thresholds whose inputs are activated when the harmonic thresholds are exceeded. A single harmonic threshold is applied to measurements from multiple phases on poly-phase systems by comparing the square root of the sum of the squares of measurements from each phase to the harmonic threshold. Three indicators show when voltage harmonic limits are exceeded, current harmonics limits are exceeded, or both voltage and current harmonic limits are exceeded simultaneously.

Abstract: An electric power measuring system wherein the watt-hour measurements are adjusted to account for the 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 used to calculate power flow direction and magnitude at various frequencies. Weighting functions are applied to power flows at frequencies other than the fundamental frequency. The weighted power flow is used to calculate an harmonic-adjusted watt measurement, which is then accumulated to form a harmonic-adjusted watt-hour measurement. The weighting functions can be selected to provide an economic incentive for a power consumer to consume power in a way that matches the goals of the power provider.

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 nonfundamental currents and voltages. The resulting harmonic-adjusted volt-ampere-hour measurement is used to calculate a harmonic adjusted power factor measurement.

Abstract: An impulse direction detector for AC power systems determines the direction of high-frequency impulses on an AC (alternating current) power line by measuring impulse parameters on each side of a low-pass filter inserted in series with the power line. The low-pass filter is formed by two capacitors and a series inductance. The series inductance is formed by placing a magnetic core around the power line. The impulse parameters are measured on either side of the magnetic core and are then transmitted to a microprocessor. The microprocessor determines if the impulse is above a threshold level and which side of the magnetic core the impulse originated from. The microprocessor then displays the direction of the impulse and communicates the result to other digital systems.

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.

Abstract: A locking apparatus is coupled to and incorporated within an electronic instrument to ensure that the instrument operates within a predetermined set of performance parameters. The instrument's operating characteristics will be tested and measured by an external, automatic test system as is typical in the manufacture of many electronic instruments. The locking device will prevent the ordinary operation of the instrument until the instrument has successfully passed the tests administered by the automatic test system. Upon successful completion of the tests, the test system will communicate a signal to the locking device. Upon receipt of the control signal, the locking device will "unlock" the instrument allowing normal operation. In order to ensure that routine calibration takes place, the locking device can be instructed to periodically disable normal operation of the instrument until another performance test is administered by an automatic test system.

Abstract: The present invention is for digital calibration of plug-in transducers and the like. The invention comprises means for digitally storing error-correcting tables in a physical location which is associated with the transducer, and a means for interpreting those tables.

Abstract: The present invention improves the accuracy of waveshape measurements and transducers. Specifically, it is a method and apparatus which calibrates a system, which comprises transducers, amplifiers, filters and analog-to-digital converters, by digitally removing phase and amplitude errors over a frequency spectrum.