Abstract: A solid-state AC energy consumption meter includes an array of AC signal transducers which provide voltage and current signals to a watt transducer chip. The watt transducer chip operates on the multi-phase voltage and current signals to produce AC energy consumption data which is fed to a register for visual display. In one aspect of the invention, a calibrating resistive component is placed in series with the input to the primary coil of the potential transformer for each phase. The value of the resistive component is calibrated to produce an appropriate change in the phase angle difference between the potential transformer secondary voltage and current transformer secondary current. More particularly, the addition of the resistance of the primary of the potential transformer provides the necessary amount of phase lead to the potential transformer to account for this phase error difference.

Abstract: A zero phase voltage measuring device for measuring a zero phase voltage of the three phase power system having an earth-fault includes an optic voltage sensor provided at any one of three power lines for detecting a current ground-to-line voltage thereat, a line-to-line voltage sensor provided between any two of the three power lines for detecting a current line-to-line voltage therebetween. A phase shifter and a multiplier are provided for calculating an ideal ground-to-line voltage at the power lines when no earth-fault is observed by changing the phase and multiplying the magnitude of the current line-to-line voltage. A subtracter is further provided to obtain a zero phase voltage signal by subtracting the ideal ground-to-line voltage from the current ground-to-line voltage.

Abstract: In a current transformer arrangement for three-wire three-phase systems, use is made of a single busing transformer (4) arranged on the three-phase side. Two of the total of three phase conductors are pushed through the bushing transformer, specifically either with the same number of turns per unit length and in mutually opposite defined directions or with the same direction and with the ratio of different numbers of turns per unit length of 2:1 or with the same direction and a current flow halved in a phase conductor by a shunt (15). These arrangements prevent the occurrence of a zero resultant magnetic flux. The double secondary voltage produced by a double AW value occurring twice during each period is halved by an electronic correcting circuit. The control commands are derived from suitable control pulses for the thyristors (21-26) of the three-phase bridge circuit (16). Two correcting circuits are specified.

Abstract: Separate pulse inputs from respective metering circuits, representing the reactive R and in-phase W power components, are converted to a pulse output V representing the vector sum of those components. The two inputs are applied to increment respective registers, the output V is held in a third register, and a fourth register is provided to store the REMAINDER value (W.sup.2 +R.sup.2)-(V+1).sup.2. The meter includes a processor for incrementing the REMAINDER value by 2W+1 for each increment of W and 2R+1 for each increment of R and for incrementing V whenever the REMAINDER value is zero or positive and at the same time reducing the REMAINDER value by 2V.sub.1 +1, where V.sub.1 is the incremented value of V. The FRACTIONAL error in the value of V is determined by means of a look-up table.

Abstract: An electrical power measuring device wherein signals (V.sub.i, V.sub.v) representing one of the current and voltage supplied to a load are applied to the input of a sigma delta modulator (9), and the state (0 or 1) of the modulator output together with the polarity of the other one of the voltage and current values, is used to determine the sense in which the digital signals representative of successive samples of the other one of voltage and current values are accumulated in an accumulator (11). The count in the accumulator (11) consequently increases at a rate representative of the power supplied to the load.

Abstract: A method and apparatus for enabling the continuous monitoring of the operational state of circuit components includes a scheme for generating a plurality of voltage signals representing neutral-to-line voltages of the system and adding to each of those signals a second signal, each second signal being identical. This addition is done vectorially to yield a modified signal. A representation of the modified signal as acted upon by the circuit to be monitored is compared with a representation of the neutral-to-line voltage signal to yield an output signal representative of the operational state of the circuit components.

Abstract: A circuit for measuring the tension of an electricity line, the circuit comprising a capacitive divider comprising first and second capacitors, first and second amplification lines for amplifying the tension across the terminals of the second capacitor, said amplification lines having respective time constants of the order of 100 ms and in the range 2.5 ms to 15 ms, the amplification lines being connected to respective first and second controlled switches under the control of a logic circuit, the circuit further including a circuit for generating the absolute value of the algebraic difference between the signals provided by the amplification lines, and a comparator circuit for providing an output signal that controls the logic circuit causing it to change state when said absolute value exceeds a given threshold.

Abstract: An optical current transformer, which uses a Faraday cell for detecting the intensity of a magnetic flux induced in a circular iron core, has plural windings having the same number of turns provided on the core in a manner that overall width of the windings are evenly wound along the whole part of the circular iron core, and terminal of the windings having the same polarities are commonly connected by cables.

Abstract: A method and apparatus for digitally measuring electrical energy consumption from a transmission line carrying alternating current. Instead of actually measuring current from a transmission line conductor, the time derivative of the magnetic field induced by current flowing in the conductor is measured thereby obtaining a reading which is proportional to the time derivative of the current flow. Using an appropriate microcomputer, the time derivative of the magnetic field (the magnetic field rate of change) is represented with an algorithmic series for expressing cyclic phenomena, such as the Fourier series of low order. An approximation of the power consumption is then computed by converting the time derivative of the current as expressed in the algorithmic series and a voltage measurement from the conductor mathematically to a power reading, and the power reading is summed to obtain a number value proportional to the energy consumption.

Abstract: An AC current sensor comprising a generally C-shaped main coil with a fixed gap between its ends. A pair of compensating coils are positioned at fixed locations in the main coil's gap. The longitudinal axes of the compensating coils lie on an imaginary straight line which extends between the centers of the main coil's ends; and their electrical centers are each spaced the same distance from their respective ends of the main coil. A compensating coil gap is defined between the electrical centers of the compensating coils. The main coil defines a measuring recess in which the sensed AC current carrying conductor is located when a measurement is taken. When the ratio of the size of the main coil gap to the size of the compensating coil gap is equal to the square root of three, the AC current sensor's accuracy and outside signal rejection increase most rapidly with increased distance of the sensed AC current carrying conductor from the compensating coil gap, and the AC current sensor's size can be minimized.

Abstract: In an arrangement for measuring an electrical power or energy, for each of a plurality of phases, the arrangement includes a voltage input in a transformer supplied with current and connected to an integrator with a high ohm input. Each transformer is connected via an integrator with a high ohm input to a mark-space-amplitude modulator, one of which is provided per phase. Each voltage input is also in communication with the corresponding mark-space-amplitude modulator. Each mark-space-amplitude modulator comprises a mark-space modulator and a pulse amplitude modulator. Each pulse amplitude modulator is provided with two push-pull outputs, each of which is connected to an input of a current/frequency converter for the integration of marks (pulses) and spaces (i.e. spaces between pulses) present at the output of the pulse amplitude modulator. The current/frequency converter is connected to processing and display circuitry for displaying an output.

Abstract: An electronic watthour meter for metering the consumption of electrical energy on power lines includes phase compensation means for compensating for leading and lagging phase differences between line current and voltage, whereby sampling times of the current and voltage are shifted to compensate for phase errors between the current and voltage by controlling timing signals provided to current and voltage analog to digital converters. Digital output signals from the analog to digital converters proportional to current and voltage are multiplied to provide an accurate representation of energy consumption as a result of the compensation.

Abstract: The disclosed porcelain insulator has built-in optical transmission media extending therethrough from a base metal secured at one end thereof to a conductor-holding fixture at the opposite end thereof. The conductor-holding fixture may carry one or both of two type sensing units: namely, a sensing unit having a current transformer (CT) coupled to the phase conductor, a load resistor connected to the CT, and an electro-optic element coupled to both said load resistor and said optical transmission medium; and another sensing unit having a capacitive potential transformer (PT) coupled to said conductor and an electro-optic element coupled to both said PT and said optical transmission medium.

Abstract: A voltage-sensing circuit producing a voltage-indicating signal representative of the voltages in a three-phase AC system produces several voltage-indicating signals which are representative of the phase voltages in a three-phase AC system. These voltage-indicating signals are squared, and the squared voltages are summed to produce an output signal having a DC voltage component with a magnitude proportional to the Mean Square value of the AC phase voltages. Unbalanced voltages in the three-phase system can be monitored by detecting the peak value of a ripple voltage imposed on the DC voltage component of the output of the circuit.

Abstract: A device for monitoring the unbalance of the electric power demanded on the conductive lines of an alternating current network of a three-phase internal installation. The device applies to all networks or three-phase installations which serve single-phase type devices in terms of variable number and power.

Abstract: A circuit for measuring voltages in a three-phase installation, in particular an installation of the metalclad type, the circuit including for each of the phase conductors: a capacitive divider including a first capacitor connected firstly to said conductor and secondly to a second capacitor (C1, C2, C3) connected to ground, the circuit being characterized in that the voltage (v1, v2, v3) of each of the second capacitors (C'1, C'2, C'3) of the dividers is respectively applied firstly to the input of an inverter (I1, I2, I3) and secondly via a first resistance (R1, R2, R3) to the negative input of an operation amplifier (A1, A2, A3) which is also connected via second and third resistances (R21, R12, R13, and R31, R32, R23).

Abstract: The invention relates to a system using Rogowski coils to measure the phase currents in a three-phase installation. Each coil (1, 2, 3) is connected firstly to a corresponding operational amplifier (10, 20, 30) connected as an integrator, and secondly to a corresponding inverter (100, 200, 300) whose output is connected to the inputs of the integrating amplifiers of the other two phases. With appropriately selected resistance values, mutual interference effects may be cancelled. The system is suitable for measuring phase currents in an installation housed in a cabinet or cubicle.

Abstract: An electric power measuring device wherein input analog signals representative of instantaneous values of current and voltage are applied to a multiplier (23) and the product applied to a converter (35, 37, 41, 43, 45, 47) to provide a pulse output signal having a frequency representative of the product and hence of the level of power consumption. Compensation for offset errors in the multiplier is effected by periodically reversing the polarity of one of the inputs to the multiplier and effecting corresponding reversals at the input to the converter to avoid irregularities in the output pulse rate when the level of power consumed is low.

Abstract: The invention finds application primarily in three phase power systems having A, B and C voltage phases. The invention includes a first voltage measurement device coupled between the A phase input and the B phase input, having a first measured voltage output. The invention further includes a second voltage measurement device coupled between the A phase input and the C phase input, having a second measured voltage output. The invention also includes a comparator having a first input connected to the first output of the first voltage measurement device and a second input connected to the second output of the second voltage measurement device, for generating a signal when the first measured voltage is equal to and opposite in polarity from the second measured voltage. This signal indicates that a zero crossover event has occurred with the A phase.

Abstract: A watthour meter, preferably for a wye connected load, includes a current transformer for sensing the load current, a resistive voltage divider network for sensing the line voltage, and a measuring circuit for calculating the AC electrical energy consumption of the load based on the sensed load current and line voltage. The load consumption calculations are performed using a Mark-Space oscillator and amplitude modulator in the watt transducer chip. Reduced voltage from the resistive voltage divider network is fed into the input junction of the Mark-Space oscillator. A feedback resistor is connected from the output junction to the input junction of the oscillator. The feedback resistor and the voltage divider network are mounted on the same thermally conductive substrate so that each are subject to the same thermal effects.

Abstract: The disclosed porcelain insulator has built-in optical transmission media extending therethrough from a base metal secured at one end thereof to a conductor-holding fixture at the opposite end thereof. The conductor-holding fixture may carry one or both of two type sensing units: namely, a sensing unit having a current transformer (CT) coupled to the phase conductor, a load resistor connected to the CT, and an electro-optic element coupled to both said load resistor and said optical transmission medium; and another sensing unit having a capacitive potential transformer (PT) coupled to said conductor and an electro-optic element coupled to both said PT and said optical transmission medium.

Abstract: A mutual inductance differential current transducer employs a toroidal coil mounted coaxially and generally centrally of the length of an alternating current conductor wiht a conductive sheet therebetween surrounding the conductor and of substantially the same length and in insulated relationship from the conductor. The axial length of the coil is less than approximately one-third the length of the conductor, and the toroidal cross-section has a longer leg parallel to the axis of the conductor and a cross-sectional area eliminating the need for external capacitive and magnetic shielding. The coil is wound with an integer number of layers of the same number of turns per layer, the total number of turns being selected to produce a predetermined range of voltage levels of the analog voltage signal output of the coil, produced in response to and representative of the differential current flow through the conductor.

Abstract: A circuit arrangement for summing power outputs is disclosed. The circuit arrangement is especially useful in connection with a multi-phase electricity meter. The arrangement includes a plurality of input circuits connected in sequence, each of which has a current-to-voltage converter and a multiplier connected to the current-to-voltage converter. A voltage-to-frequency converter is connected at the output of each multiplier. Starting, at least with the second input circuit in the sequence, an adder is connected to the voltage-to-frequency converter by means of two inputs of the adder. Two other inputs of the adder are connected to two outputs of the preceding input circuit in the sequence. Illustratively, two outputs of each adder form two outputs of the corresponding input circuit. A ternary encoder followed by a ternary decoder may be located between the outputs of one input circuit and the adder of the succeeding input circuit.

Abstract: The invention interfaces a two-wire 60 Hz circuit to two circuits, each unidirectional, sending and receiving, and carrying frequency modulated audio tones containing the amplitude and phase of the 60 Hz voltage impressed on the 60 Hz circuit. The invention is used to interface differential relays used by electric utilities to detect power transmission line faults to a four-wire voice band communication line.

Abstract: An electronic watthour meter employs a first analog signal representing either a load current or voltage to pulse-width-modulate a second analog signal representing the other of the load current or voltage. The resulting signal contains a DC component proportional to the product of current and voltage. AC components are removed from the product signal in an integrator before applying the DC component to a threshold circuit. The threshold circuit alternates its output between positive and negative values each time the DC component of the product signal passes through a predetermined positive and negative value. This pulsed signal is transmitted to a register for integrating the energy usage. A pulse-width modulator produces a constant-frequency pulsed output whose positive and negative alternations have lengths which are proportional to the line signal it receives. At each alternation of the pulsed signal, the output of the pulse-width modulator alternates between a direct and an inverted signal.

Abstract: The invention comprises a protective relay with selective phase selection in electric power distribution systems when there are double transmission lines (M1-P1,M2-P2) between two stations (TM, TP) and where the ends of the line are connected to a common busbar system located in each station. The protective device includes a protection unit, terminal, at both ends of each line. All the terminals (M1, M2, P1, P2) include an identical basic design for measurement of phase quantities (17), filtering (18) and A/D conversion (19); furthermore, the identical part includes a parameter estimator (20) for Fourier series expansion of measured phase signals and generation of the respective residuals. The parameter estimator cooperates with a frequency estimator (21) and a sampling regulator (22).

Abstract: An electronic circuit arrangement for producing an output signal representative of the average value of an alternating voltage in a power transmission system, composed of: at least one circuit unit composed of a pulse width modulator (6) connected to derive, from the alternating voltage, a train of pulses modulated in width as a function of the amplitude of the alternating voltage and with a defined phase relation to the alternating voltage, an electronic circuit (4,8) connected to derive, from the alternating voltage, an alternating signal which varies in frequency with the alternating voltage and which has the defined phase relation to the alternating voltage, and a signal multiplying device (14) connected to receive the train of pulses modulated in width and the alternating signal for multiplying the pulses and the alternating signal to produce a product signal having an amplitude proportional to the average magnitude of the alternating voltage; and a signal to frequency converter (16) connected to derive

Abstract: A current-comparator technique for obtaining an instrument for accurate high voltage power measurements at very low power factors is described. The quadrature component of the load current is automatically balanced in the current comparator against a quadrature current obtained from a slave supply, thereby reducing the stringent high accuracy requirement of the instrument when used for measuring power at a very low power factors. The current-comparator-based instrument according to the present invention has an estimated accuracy with respect to its readings of better than 3 percent at 0.001 power factor, 1 percent at 0.005 power factor and 0.5 percent at 0.01 power factor and higher. It features an internal high-voltage active-divider and displays to indicate source voltage, current, power factor and reactance of the load, in addition to the power.

Abstract: An apparatus for measuring the direction of power flow through conductors connecting a load to a source of alternating electric current, the load being capable of generating electric current, and the source of alternating electric current being capable of accepting power flow from the load. The invention comprises at least one wattmeter connected so that the sum of their outputs is proportional to the power flow through the conductors and the sign of the sum of their outputs is indicative of the direction of the power flow. A detector is provided for detecting the sign of the output of the at least one wattmeter. The detector is capable of generating an indicator signal. The indicator signal has a first value when the power flows from the source of alternating electric current into the load and the indicator signal has a second value when power flows from the load into the source of alternating electric current.

Abstract: Disclosed is an apparatus and method for sensing power in a variable frequency machine. The power is sensed in each phase of the three phase machine by utilizing Hall generators for multiplying the phase current flowing through each phase by a current proportional to a phase voltage for each phase. The products are then summed to obtain a reading of the instantaneous power drawn by the three phase machine. The AC component is filtered out of the summed signal using a multi-stage filter which allows for maintaining of a fast response time with low ripple. In a preferred embodiment, a four stage filter utilizing R.C. filters is employed for this purpose.

Abstract: A master metering module is taught which utilizes a programmed microprocessor and externally operated switches to alert the module as to what kind of system is being monitored thereby. For example, is the system being monitored a .DELTA.-connected electrical system or a Y-connected electrical system. This is useful in providing output indications of line-to-line voltage or line-to-neutral voltage, for example. When measuring voltages whether line-to-line or line-to-neutral one voltage value is substituted from another. A differential amplifier is utilized to do this. In one case the differential amplifier subtracts one line voltage from another line voltage, but in another case it subtracts neutral or zero ground potential from a line voltage. A switching arrangement is provided which interconnects one terminal of the differential amplifier with the neutral input terminal and with a line input terminal through appropriate conditioning of the microprocessor.

Abstract: An alternating current watt transducer including an integrated circuit analog multiplier, providing four quadrant multiplication, to the input terminals of which are applied alternating current signals proportional to the voltage and current determinative of the watts to be measured. The integrated circuit analog multiplier provides an alternating current output signal which being proportional to the product of the in-phase components of the input signals, is proportional to the watts being measured. The alternating current signal which is proportional to watts is transformed to a constant-current direct current output.

Abstract: A switched-capacitor integrator is employed in an electronic watthour measurement device for integrating the average component of a product signal formed by pulse-width modulating an analog signal proportional to one of a load current and voltage at a pulse duty ratio proportional to the other of the load current and voltage. A hysteresis comparator forces the direction of integration to alternate between positive and negative limits for balancing out offset voltages in the integrator and comparator. A triangular-wave generator employed as part of the pulse-width-modulation technique is also implemented using a switched-capacitor integrator. The switched-capacitor integrators permit fabrication of the circuit with the required accuracy without needing external, discrete time-constant-determining resistances and capacitances. Measurement accuracy is determined by the ratio of capacitances of two on-chip capacitors, the accuracy to a clock signal and two reference voltages.

Abstract: A polyphase, socket-style meter employs identical left and right current stators. The angles about the meter disk, at which the left and right current stators are located, are adjusted to place the centers of their cores in alignment with their connector tabs. Identical current stator coils encircle the cores. The axes of the cores are slightly skewed with respect to the axes of the coils. The diameters of the coil helices are made large enough to accommodate the skew.

Abstract: A disk for an electric meter includes a solid annulus of a conductive material with a center of the annulus filled with a non-conducting material. The non-conducting material is preferably molded in place both to capture the annulus and to secure a disk shaft into a unitary assembly. The annulus distorts eddy currents at distances from sets of potential and current stators of the electric meter to minimize radial components of eddy currents in the vicinity of neighboring sets of potential and current stators. The reduced radial components of eddy currents reduces the constructive or destructive interaction of the eddy currents with their neighboring sources of flux. Increasing the angular separation of the sets of potential and current stators further reduces interaction.

Abstract: Apparatus is provided for simultaneously measuring and displaying voltage, current and frequency in a polyphase alternating current system. The apparatus is operable in either a line-to-line or a line-to-neutral measuring mode without rewiring the apparatus to the measured system. A logic circuit is selectively operated to connect the appropriate voltage lines associated with each phase of the system to the apparatus and LEDs associated with each phase light to indicate the phase selected for measurement. Multi-digit seven segment LED displays are provided for simultaneously indicating the voltage, current and frequency measured.

Abstract: A meter junction box for enabling the safe, accurate and efficient measuring of components of multi-phase electric power includes two separate spaced enclosure housings. The two housings are interconnected by a plurality of electrically conductive, non-magnetic conduits which are environmentally sealed at each end thereof in a manner to secure the interior of each housing from the adverse effects of the environment. A single, insulating jacketed electrical conductor passes through each of the respective conduits from one of the housings to the other. The individual conduits provide a means whereby a hook-on type ammeter may be functionally and individually connected with the conduits to measure the current in the conductor passing therethrough.

Abstract: A method is provided for measuring the torque of an AC motor (4) without a mechanical transducer by sensing input voltage, and input current regardless of phase, and determining the torque therefrom.

Abstract: A plurality of single-phase energy sensors each having a first input connected to a current converter and a second input connected to voltage converter supply pulses to a calculating device. The number of pulses over time represents the energy detected by the single-phase sensor. The calculating device is based on a microprocessor and comprises accumulators controlled by the pulses delivered by the energy sensors for supplying the active and reactive power measurements sought. In the case of a four-wire network, it is not necessary to use voltage transformers for the interphase network voltages, and the energy sensors supply pulses which represent the active and reactive energy of each phase.

Abstract: A pulse width modulator for an electronic kilowatt-hour meter includes an integrator having its inputs connected to a square wave clock signal and a sine wave signal proportional to the time derivative of current on the metered circuit. A plurality of series-connected inverters are connected to the output of the integrator to function as a comparator which generates a pulse width modulated signal having a duty cycle proportional to metered current. A negative feedback path including a low pass filter is connected between the output of the last inverter and an input to the integrator to compensate for errors produced by the integrator and inverters, thus permitting the use of low cost inverters fabricated on an integrated circuit.

Abstract: An electronic solid state Q-hour meter for measuring leading and lagging VARS quantities of electric power over a defined range of power factor. The Q-hour meter comprises first and second time division/pulse width-amplitude modulated/analog multiplier circuits. First and second current transformers are coupled to first and second phases of a multi-phase power supply to be monitored for deriving first and second analog circuit indicating signals which are supplied to respective analog current input terminals of the analog multipliers. First and second potential transformers are coupled across the first and second phases of the multi-phase power supply for deriving first and second analog voltage indicating signals that are supplied to respective input terminals of the first and second analog multiplier circuits.

Abstract: The DC content of an AC waveform is detected by a digital filter which partially filters each phase of the waveform and applies the filtered waveforms sequentially through a multiplexer to a sample and hold circuit which measures the instantaneous value of each phase at two points which are spaced an exact odd number of half cycles apart. The time interval between the measurement points is adjusted according to variations in the AC waveform frequency to maintain required spacing. The measured instantaneous values are fed by an analog to digital converter and to a microprocessor system which averages the two readings to generate a signal corresponding to the DC content for each phase.

Abstract: An improved solid state semiconductor integrated circuit electronic watt/watthour meter circuit having analog and high frequency digital outputs with automatic error correction. The meter comprises first and second transformers for developing first and second voltage and current indicating signals for supply to a multiplier circuit that multiplies the two signals together and derives an output analog product signal representative of the instantaneous power being supplied by a source of electric energy. A multiplier low pass filter circuit is coupled to the output from the multiplier circuit for deriving from the product signal an average value power signal V. An analog-to-pulse rate converter is supplied with the average value power signal V and serves to convert it into a high frequency train of output signal pulses wherein each output signal pulse represents a predetermined quantized amount of electric energy.

Abstract: The DC content of each phase of a three phase AC waveform is generated by partially filtering each phase and applying the filtered waveforms sequentially through a multiplexer to a sample and hold circuit which measures the instantaneous value of each phase at two points which are spaced an exact odd number of half-cycles apart. These instantaneous values are fed by an analog to digital converter into a microprocessor which averages the two readings to generate the DC content for each phase and compares the highest DC content with a threshold value. The excess of the highest DC content over the threshold value is integrated and an output signal is generated when the accumulated volt-seconds exceed a selected value.

Abstract: An electric energy meter includes a mutual inductance current transducer formed by primary winding means for direct connection to the current component of an electric energy quantity to be measured. Secondary winding means is inductively coupled to the primary winding means to produce an analog signal that is proportional to the time derivative of the current component. The current responsive analog signal and a voltage responsive analog signal are both applied to an electronic watthour measuring circuit.

Abstract: An improved solid state semiconductor electronic combined watthour and watt meter circuit providing both analog and digital outputs and having automatic error correction comprising first and second input transformers for developing first and second signals proportional respectively to the voltage and current being supplied from a source of electrical energy to a consumer. The first and second signals are supplied to a multiplier circuit for developing pulse-width-modulated and amplitude modulated product output signals representative of instantaneous watts. This product signal is supplied to a summing analog-to-pulse rate circuit for developing an output pulse train wherein each output pulse represents a predetermined quantized amount of energy and which is used to reverse polarity of the multiplier switches to accomplish automatic error correction.

Abstract: An electronic watthour meter includes a power flow direction detector circuit which detects the power flow direction and a pulse width modulation circuit for converting a voltage signal proportional to the load voltage into a pulse signal. In accordance with the output of the power flow direction circuit, the polarity of the output signal of the pulse width modulation circuit is either inverted or not inverted. A multiplication circuit produces the product of the voltage signal proportional to the load voltage and a voltage signal proportional to the load current under the control of the output of the pulse modulation circuit.

Abstract: An electronic arrangement for determination of reactive power, including two transducers delivering at their outputs measuring voltages proportional to supply current and supply voltage. An additional phase shift of 90.degree. between the two measuring voltages is produced by phase-shifting elements. A signal proportional to reactive power is produced in a following multiplier element. To preclude as far as possible variation of amplitude and phase shift occurring on frequency fluctuation in a frequency range close to rated frequency of the power supply, an all-pass is connected as a phase-shifting element ahead of each of the two respective inputs of the multiplier element whereby one all-pass is designed to produce a phase shift of +45.degree. and the other all-pass is designed to produce a phase shift of -45.degree. at the rated frequency of the power supply.

Abstract: A method of detecting symmetrical components of a three-phase supply-line voltage comprises the steps of converting three-phase voltage to alternating single-phase voltage with the aid of at least two function generators (2), (3), with at least one of said function generators being an active-reactive circuit, which conversion of a three-phase voltage is effected by altering said supply-line voltage in amplitude and phase in said active-reactive circuits, and subsequently summing up output voltages of the function generators (2), (3), to produce symmetrical components of said three-phase voltage, forming a control signal proportional to a disturbance influencing the output voltages of the active-reactive circuits (4) and compensating said disturbance influence by control action, wherein according to the invention said control signal is formed from the difference in voltage drop between elements (5), (6) in each active-reactive circuit, and compensating said disturbance influence is done by summing up said cont

Abstract: An electronic wattmeter in the form of an electronic watt-transducer circuit requiring a minimum number of components that can be fabricated by monolithic semiconductor integrated circuit manufacturing techniques and which provides a direct current output signal that is proportional to watts. The electronic watt transducer circuit comprises a first transformer for developing a first voltage related signal proportional to the input voltage to be measured and a second current transformer for developing a second current related signal proportional to the input current to be measured. A pulse width modulator is connected to receive the first voltage related signal and an input repetitive sampling signal for producing repetitive pulse width modulated output pulses having instantaneous pulse width proportional to the corresponding instantaneous amplitude of the first voltage related signal.