Abstract: An electronic watthour meter is digitally configurable to operate as several different types of watthour meters for metering electrical energy from a variety of different electric utility services. Automatic scaling of line input currents is provided to scale the voltage input to an analog to digital converter over selected ranges such that low level and high level input signals are measured in an optimum range. A digital signal processor is employed to calculate values for metered electrical energy and output pulses, each proportional to a quantum of energy flowing in the circuit being metered. The processor calculates the value of DC offset errors inherent in the various analog circuits of the meter and uses that value in the calculation of metered electrical energy to compensate for such offset errors. The meter employs automatic and manually initiated test functions for testing the operation of the processor and other critical circuits in the meter.

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: A modular versatile electronic energy meter is provided with current voltage and register modules which may be selected and readily interconnected along with a selected output circuit board and including a plurality of features which may be customized late in the manufacturing cycle or after manufacture, including jumpers adapted to be selectively cut and attachable switch restrictors. Reduction and standarization of components and uncomplex interconnections are provided, along with apparatus to assure proper assembly and testing of the modular meter.

Abstract: An improved DC stabilization system is provided in an electronic digital power meter of the type utilizing current transformers to scale and isolate the power line current and an analog to digital converter to convert the meter currents to a digital signal for signal processing. An unmodulated square wave signal is provided to trigger a chopper switch which connects the current transformer to an amplifier and provides a current signal output. A feedback current from the amplifier is provided through the feedback and sense windings of the current transformer by the chopper to compensate for the effects of DC offset voltage at the input of the amplifier. The square wave is a low frequency such that its harmonics and those of the power lines are different to minimize the gain bandwidth requirements of amplifiers in the system.

Abstract: An auto-ranging circuit for an electronic watthour meter employs high- and low-range sources for increasing the dynamic range over which satisfactory measurement accuracy can be maintained. A counter, having a capacity equal to the ratio of high-range to low-range is interposed in the output during use of the low-range source so that output pulses have the same energy-consumption significance at all time. At transition from low-range to high-range, any residue in the counter, representing energy consumed but not yet recognized by the generation of an output pulse, is preset into an integrator of the electronic watthour meter for reducing correspondingly the amount of energy consumption required to produce an output pulse in the first measurement cycle following the low- to high-range transition.

Abstract: A battery backup installation for a time of use register for an electric meter is mounted within a case of the electric meter. The case includes a hatch which permits removal and replacement of the battery without requiring removal of the case from the meter. In one embodiment, the battery is installed in a battery clip on the face plate of the meter where it is accessible through the hatch. An extra length of wires from the battery permits the battery, and its mating connectors, to be withdrawn through the hatch for replacement thereof. In a second embodiment of the invention, the battery is captured in a door of the hatch and is withdrawn from the meter by the action of opening the hatch. In this embodiment, the hatch may be hinged or not hinged. Battery replacement is facilitated while the electronic register module is separated from line-supplied power. An auxiliary battery provides an auxiliary source of backup power during batterychange.

Abstract: A meter terminal unit, for acquiring information and transmitting the acquired information to a central reading and control unit over utility power transmission lines, includes a transmitter portion for synthesizing and modulating carrier waveforms, the frequencies of which are selectable by command data contained in frequency rotation and address fields of a command received from the central reading and control unit. The meter terminal unit receives and decodes the command and adds, in modulo form, the contents of the frequency rotation field to the contents of a portion of the address field to obtain a resultant sum which uniquely identifies the selected waveform. This sum is used to access a portion of a read only memory (ROM) having the selected waveform stored therein in digital data form. The selected waveform is reconstructed by outputting the digital data from the ROM to a digital to analog converter.

Abstract: An automatic meter reading and control system for communicating with remote terminal points includes a reading control center which selectively communicates with a meter terminal unit at each terminal point by way of a section control unit, each section control unit serving several meter terminal units. The section control unit is responsive to various commands issued by the reading control center to selectively route the commands to specified meter terminal units or groups of meter terminal units to direct the meter terminal units to selectively carry out a meter reading operation, a load control operation, a user alert operation or transfer of previously stored meter data or switch status data from the meter terminal units to the reading control center in accordance with functions specified by the various commands.

Abstract: An automatic gain control circuit and system for using same provides linear attenuation response to input data signals of multiplexed frequencies of high and low signal amplitudes to eliminate frequency intermodulation products generated by the data signals of high amplitude from interfering with the reception of the proper data signals by a tuned receiver communicating with the automatic gain control circuit.

Abstract: Achieving N-key rollover by detecting the leading edge of the binary coded signal generated in bit parallel form in response to keyboard key depression and blocking the receipt of data representing a subsequently depressed key where the width of each binary bit signal is less than the interval between two successive system timing pulses which in turn is much less than the 10 millisecond or so interval between successive key operations by an operator as a result of rollover typing.