Abstract: A circuit for converting changes in a sensed physical parameter, such as resistance and resistance change as a function of pressure, temperature and the like, into a digital signal of proportional frequency. A sensor bridge, monitoring the parameter to be measured, forms a part of a feedback loop controlling a current into a resistance-capacitance integrator which is part of a controlled oscillator. The oscillator has automatic offset error correction. The frequency of the sensor-controlled is proportional to the unbalance in the sensor bridge. The converter receives power on a two-wire line from a power supply which may be located remotely therefrom, and from which power supply the sensed-parameter-established frequency is extracted for use by processing-control apparatus and the like.

Abstract: A circuit for sensing the magnitude of an AC signal applied to the circuit includes control means for reversing the polarity of the AC signal to thereby generate an output signal which is proportional in amplitude to the magnitude of the AC signal and which has a phase, with respect to the phase of the AC signal, determined by the control means. The control means also provides the capability of generating output pulses from the circuit which have an amplitude proportional to the magnitude of the AC signal and a pulse-width-spacing proportional to the duty cycle of a pulsating control signal applied to the control means.

Abstract: Apparatus for providing automatic compensation of direct current magnetization of a current transformer in an alternating current watthour meter utilizing a magnetic field sensor and electronic circuitry to keep the transformer operating in its linear region when a DC component is superimposed on an AC current being provided to the transformer.

Abstract: A hybrid sensor for simultaneously sensing pressure and temperature in non-interacting manner, includes an insulative substrate having a temperature-sensitive printed thick film resistor fabricated thereon. A conductive plate is insulatively spaced above the resistor and supported by a pressure-tight insulative barrier. The distributed capacitance between the plate and the resistive pattern is a function of the pressure applied to the exterior face of the plate, while the resistance of the resistive thick film is a function of temperature of the surrounding environment.

Abstract: A watt hour meter installation is described which is of the type including an input transformer having an input winding for connection to an alternating current power supply line, an output winding for connection to a watt hour meter for measuring alternating current power being consumed and a bore on which the input and output windings are wound. The core is of the type which is susceptible to DC magnetization by a DC component superimposed on the alternating current being measured. In order to overcome the effect of the DC component on the magnetization characteristics of the input transformer, automatic compensation circuitry is provided which includes a sensor coupled to sense the current flowing through the input winding and for deriving a sensed output signal proportional to the sensed current and which includes both AC and DC components of the input current.

Abstract: A watthour meter installation of the type including an input current transformer having an input winding for connection to an AC power supply line, an output winding for connection to a watthour meter for measuring AC power being consumed and a core on which the input and output windings are wound and which is susceptible to DC magnetization by a DC component superimposed on the AC being measured. In order to overcome the effect of the DC component on the magnetization characteristics of the input transformer, automatic compensation circuitry is provided which includes a sensor coupled to sense the current flowing through the input winding and for deriving a sensed output signal proportional to the sensed current which includes both AC and DC components of the input current.

Abstract: An electronic energy consumption meter and system includes means for automatically correcting for overall system signal and voltage errors and offset errors created by circuits in the system to provide a meter requiring no adjustments for the compensation of the various system and circuit errors.

Abstract: Apparatus and method of compensating for a shift in the phase of the current applied to a current transformer terminated in a low impedance operational amplifier. The operational amplifier phase response is altered to minimize the phase angle between the transformer current and the amplifier output voltage to thus provide an output voltage directly proportional to the transformer current.

Abstract: An electronic kWh meter is disclosed which measures electrical energy consumed in an electrical system. A current transformer generates an analog voltage which is proportional to a current in the electrical system. An operational amplifier has an input resistor connected across the load impedance of the electrical system and has a feedback resistor connected across the input and output of the amplifier. The input resistance of the amplifier is very small compared to the resistance of the input resistor to thereby virtually isolate the operational amplifier from the electrical system. The operational amplifier generates an output signal which is proportional to the voltage across the load impedance in the electrical system. The inphase components of the voltage and current are multiplied to provide a signal which is proportional to the instantaneous power in the system. This signal is converted to a pulse train wherein each pulse represents a quantized amount of energy consumed within the system.

Abstract: An electronic meter for measuring V.sup.2 hr in an electrical system includes a center tapped transformer for deriving two analog signals proportional to a detected voltage in the system with the analog signals being 180.degree. out of phase with respect to one another. A comparator compares a relatively high frequency triangular signal with a selected one of the analog signals with the output of the comparator driving a switch which acts as a multiplier. When a comparison exists the switch couples one of the analog signals to an integrator, and when a comparison does not exist, the switch couples the other analog signal to the integrator. The output of the comparator is a pulse width modulated signal having a time duration which is proportional to the amplitude of the detected voltage in the system, and the signal coupled to the integrator is a chopped analog signal having an amplitude proportional to the amplitude of the voltage in the system and a time duration proportional to the magnitude of the voltage.

Abstract: An electronic kilowatt-hour meter having internal error correction is disclosed for metering electrical power and energy consumption in a single phase or polyphase electrical system. A comparator compares an analog signal which is proportional to the voltage in the system with a relatively high frequency triangular waveform. The output of the comparator which is a pulse width modulated signal having a pulse duration proportional to the amplitude of the voltage in the system is multiplied by a signal which is proportional to the current in a system. The output of the multiplier is integrated to thereby provide a signal which is proportional to the energy consumed in the system. The output of the integrator is converted to a pulse train having a frequency which is proportional to the amplitude of the output signal of the integrator, and hence is proportional to the kilowatt hours consumed in the electrical system.

Abstract: A two-way electronic kWh meter is disclosed for metering electrial power and energy consumption in a single phase or polyphase electrical system wherein power and energy may be imported to the system or exported from the system to another system. Pairs of analog signals representing current and voltage variables are derived. Each pair of analog signals is multiplied together to derive partial instantaneous power signals. These signals are summed and integrated to thereby provide a signal which is proportional to the total energy being imported or exported with respect to the electrical system. The output of the integrator is converted to a pulse train having each pulse proportional to the energy being imported or exported with respect to the system. The partial instantaneous power signals are also summed and averaged, with the polarity of the resulting signal being detected by a polarity detector.

Abstract: Metering kWh in an electrical system is accomplished by generating pairs of analog signals representing current and voltage variables. A comparator compares an analog signal which is proportional to the voltage in the system with a relatively high frequency triangular waveform. The output of the comparator, which is a pulse-width modulated signal having a pulse duration proportional to the amplitude of the voltage in the system, is multiplied by a signal which is proportional to the current in the system. The output of the multiplier is integrated to thereby provide a signal which is proportional to the energy consumed in the system. The output of the integrator is converted to a pulse train having each pulse proportional to the kilowatt hours consumed in the electrical system. A mechanical accumulation and display means records the total energy consumed and is driven in response to the output of the analog-to-pulse rate converter.

Abstract: A digital electrical pulse filter which provides output electrical pulses directly corresponding to input electrical pulses when the input pulses have a repetition rate greater than a predetermined repetition rate and which provides no output pulses when the input pulses have a repetition rate less than the predetermined repetition rate. An electronic energy consumption meter employing such a low cutoff digital pulse filter is also disclosed as well as a specific circuit for the filter employing complementary pairs of C-MOS active elements in an arrangement which facilitates construction of the entire filtering circuit according to C-MOS integrated circuit construction techniques and which enhances the overall operation of such an integrated circuit filter.

Abstract: Metering kWh in an electrical system is accomplished by generating pairs of analog signals, representing current and voltage variables. Each pair of analog signals is multiplied together in a direct pulse-width conversion in a time-division multiplier network. A constant amplitude triangular generator is associated with the multiplier and the multiplier is implemented using C-MOS technology. A separate direct pulse-width multiplier network is provided for multiplying without introducing any phase shift each of the pairs of analog signals to form a series of width and amplitude-modulated pulse signals. The series of modulated pulse signals is converted in, for example, a low-pass filter to a signal having an amplitude representative of average power. For polyphase systems, the signals delivered from each of the multiplier channels are summed at the low-pass filter.

Abstract: A variable gain electronic current transformer for detecting the current flow into a power consuming system. An operational amplifier amplifies the detected current and the output of the operational amplifier is converted into a magnetic flux field which is directed onto one surface of a Hall effect element. A variable current source supplies current to a second orthogonal surface of the Hall effect element to thereby generate an output voltage which is directly proportional to the product of the output of the operational amplifier and the variable current source. This output voltage from the Hall effect element is coupled back to the input of the operational amplifier.

Abstract: An auto-ranging system for an electronic watt-hour meter includes a current transformer for measuring the electrical current in at least one line of an electrical power consuming system. The measured current is converted to a voltage which is proportional to the measured current by means of a current/voltage converter. A means responsive to the output of the current transformer incrementally varies the gain of the current/voltage converter inversely as the level of the measured current reaches each of a plurality of successively increasing discrete current levels. The output of the current/voltage converter is multiplied by the line voltage which is detected by a potential transformer with the output of the multiplier being coupled to an analog-to-pulse rate converter. The analog-to-pulse rate converter generates a pulse train having a pulse rate which is proportional to the product signal at the output of the multiplier.

Abstract: Metering kWh in a single phase, 3-wire, F.sub.L Hertz a.c. electrical system is accomplished by detecting the current flow in two lines of the three-wire system by means of a current transformer having two primary windings and a single secondary winding. The voltage in the system is detected by means of a potential transformer having the primary windings thereof connected across the load impedances and having the secondary thereof connected to a pulse width amplitude modulated multiplier. The multiplier derives a signal which is proportional to the current in the system and the detected voltage across the load impedances thereof. The output of the multiplier is converted to a d.c. voltage which is proportional to the total average power consumed by each of the load impedances with the d.c. average power voltage being converted to a pulse train by an analog-to-pulse rate converter.

Abstract: A current transformer and transresistance amplifier are combined; the secondary winding of the current transformer being connected to the input of the transresistance amplifier and being virtually short-circuited because of the very low input impedance of the transresistance amplifier. The transresistance amplifier, nevertheless, supplies an output voltage which is proportional to current in the primary winding of the current transformer. An output voltage is developed from the current in the secondary winding. An important advantage, among others, of the subject combination is that a current transformer having considerably lower volt-ampere capacity may be employed. A current transformer employed alone for the same purpose would have to have a much larger volt-ampere capacity.

Abstract: Metering kVA and kVAh in an electrical system is accomplished by generating pairs of analog signals representing current and voltage variables. Each of the analog signals is synchronously rectified to provide a pair of full-wave rectified signals which are multiplied together in a pulse-width amplitude multiplier network to produce a product signal having a DC component which is proportional to the product of the voltage and current variables. In addition, the product signal includes AC components which are filtered out in a low pass filter to thereby provide an output signal which is proportional to the apparent power in the electrical system. The apparent electrical power signal is converted to an apparent electrical energy signal by means of an analog to-pulse converter wherein each output pulse thereof corresponds to a predetermined amount of apparent energy in the electrical system.