Abstract: A current sensor employs a main resistor of a low temperature-coefficient material for producing a voltage drop proportional to a load current therein. A second resistor, also of a low temperature-coefficient material, and preferably having a resistance substantially exceeding that of the main resistor, is connected in parallel with the main resistor. The current divides between the main and the second resistors according to the ratio of their resistances. An output signal, reduced at least in accordance with a ratio of resistances of the first and second resistors, is obtained from the second resistor. Resistive heating of the main resistor is reduced by using a short path length in the direction of current flow and as large an area transverse to the direction of current as possible. A current transformer may employ the second resistor as a primary to step down further the current in the output signal.

Abstract: An output connection and signal conditioning circuit board is selected and detachably connected to an electronic energy meter to customize its functions. Connectors are provided at the ends of the circuit board to mate with an edge connector in the bezel of the register and spaced holes in the base. A separate flexible connection to the KYZ terminals is provided, along with an intermediate tab and slot to position the circuit board and strengthen the meter. A selected circuit board is added to the manufactured meter to meet customer requirements by inserting a pin connector at the bottom of the circuit board through the spaced holes, and rotating the circuit board to mate with the tab and the edge connector.

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: A unitary combination actuator and indicator flag for an electronic energy meter. The integral actuator and mode indicator is slidable within the bezel of the meter and in the off position is not visible. Sliding the actuator simultaneously moves a camming surface over an axially moveable switch to connect the meter test mode, and slides a visible "TEST" flag over the digital readout window to indicate that the watthour meter is in the test mode. Positive actuation and positioning members are included for both the off and on positions.

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: A metering system includes an electronic register having a non-volatile storage into which data is written upon the detection of a power outage. A power supply and monitor provides a regulated voltage for the electronic register and contains a capacitor which normally stores a sufficient quantity of electric energy to continue operation of the electronic register for a long enough period of time to complete the writing of data to the non-volatile storage. The discharge rate of the capacitor is linearly controlled to sustain the regulated voltage at its normal regulated value for the required period of time. An electronic meter is shut down upon the detection of a power outage to remove a portion of the load on the power supply to aid in sustaining the regulated voltage for the required period of time. The detection of momentary power outages is prevented by forcing the capacitor to charge to a prescribed voltage level before a subsequent outage can be detected.

Abstract: An output connection and signal conditioning circuit board is selected and detachably connected to an electronic energy meter to customize its functions. Connectors are provided at the ends of the circuit board to mate with an edge connector in the bezel of the register and spaced holes in the base. A separate flexible connection to the KYZ terminals is provided, along with an intermediate tab and slot to position the circuit board and strengthen the meter. A selected circuit board is added to the manufactured meter to meet customer requirements by inserting a pin connector at the bottom of the circuit board through the spaced holes, and rotating the circuit board to mate with the tab and the edge connector.

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 electronic energy meter is provided with a plurality of push button switches on the face of the meter which are selectively actuated by an actuator extending through the transparent cover to display various different meter functions. Switch restrictors are removably provided around a section of the actuator of selected switches which may then be readily actuated only from the inside of the meter, after unlocking and removing the cover.

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: An electric watthour meter includes apparatus for delaying a seasonal rate change until data accumulated in the meter is read out. Dates in a rate-change library, consisting of dates on which a rate change is authorized, are compared each day with the current date. When a match between a rate-change date and the current date is found, an arming signal is generated. The arming signal remains ineffective until a reset signal is generated at the completion of meter reading. Following the reset signal, the arming signal is reset.

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 modular electronic demand register for an electric meter is enclosed in an insulating housing into which substantially all components are installable by drop-in, snap-together methods. A display is dropped into the housing and metallic contact pads thereof are interconnected with corresponding metallic contact pads on a printed circuit board using a resilient contact strip of a type having parallel longitudinal resilient conductors insulated from each other by an insulating resilient matrix. The as-formed contact strip is slightly longer than the distance between the two sets of metallic contact pads which it interconnects, whereby, when the printed circuit board is tightened in place, the contact strip is compressed slightly to provide a stable, resiliently urged fit. Guide surfaces on the electronic demand register cooperate with surfaces on the remainder of the electric meter to guide the electronic demand register into its operational position and to lock it in place.

Abstract: A memory programmer interface for an electronic demand register includes conductive pads on a circuit board within a housing of the electronic demand register and spring-pin connectors which fit through slots in the housing of the electronic demand register into resiliently urged contact with the conductive pads. In the preferred embodiment, the conductive pads are enlarged solder pads associated with a non-volatile memory in the electronic demand register. A pair of alignment pins on the memory programmer guidingly enter alignment holes in the housing and/or the circuit board of the electronic demand register to provide alignment between corresponding ones of the conductive pads and the spring-pin connectors. The memory programmer includes a power source sufficient to energize at least selected portions of the electronic demand register and a control signal generator for generating control signals including a signal for maintaining a microprocessor in the electronic demand register in the reset condition.

Abstract: A non-volatile memory copy programmer provides temporary storage into which data can be read out from a non-volatile memory of an electronic demand register of an electric meter and from which the stored data can be written into a non-volatile memory in a replacement demand register. The non-volatile memory copy programmer also produces control signals for controlling reading and writing in the non-volatile memory. A power monitor circuit in the demand register enables the storage of data from a volatile memory to the non-volatile memory in the event of a loss of power and enables restoring the data from the non-volatile to the volatile memory when the power is restored.

Abstract: A display temperature compensator employs the non linear temperature coefficient of resistance of a thermistor to non linearly vary the control voltages fed to a liquid crystal display. At low temperature, substantially the entire supply voltage is available to control the liquid crystal display segments. At higher temperatures, the thermistor contracts the range of control voltages fed to the display in order that non-selected display segments remain off. A thermistor is used which has a non linear temperature coefficient of resistance which, when combined with selected fixed resistance value, substantially compensates for the non linear threshold voltage of the liquid display.

Abstract: An electronic demand register divides a demand interval into a contiguous set of N demand subintervals. The demand in each demand subinterval is summed with the demands from the N-1 most recent contiguous demand subintervals to derive the interval demand. The interval demand is compared with a prior stored maximum demand to decide whether to discard the present interval demand or to use it to replace the previously recorded maximum demand. Demand is accumulated in terms of actual power usage by scaling power usage pulses according to the relationship in the particular meter on which the rolling demand register is used. Thresholds are provided for producing warning signals to alert the consumer to an actual or impending demand condition which may adversely affect billing.

Abstract: An electronic demand register for an electric meter includes a plurality of pushbutton controls for controlling material displayed or a mode of operation of the demand register. A lockable switch actuator includes an actuating paddle within a cover or housing of the meter which, when unlocked, can be rotated into alignment with a selected one of the pushbutton controls and then pushed inward to actuate the selected pushbutton control. A pair of bosses bracketing one of the pushbutton controls prevents actuation of its respective control until the actuating paddle is accurately positioned between them. A second pair of bosses bracketing another of the pushbutton controls are spaced too closely apart to permit the actuating paddle to pass therebetween and they thus prevent actuation of their respective pushbutton control.

Abstract: An electronic demand register performs rolling demand metering in which a demand interval is divided into N subintervals. At the end of each subinterval, the demand data from the just-completed subinterval is summed with the demand in the most-recent N-1 contiguous subintervals to derive an interval demand. A test operation is provided in which the stored maximum demand, a number representing the remainder of the subinterval interrupted by the test and programmed constants are stored in non-volatile memory but are also retained in the processor for use during test. A test reset switch resets accumulated demand data and presets the subinterval timer to predetermined values from which they may be operated by a calibrated test load to confirm the performance of the demand register. At the end of testing, all data in the processor is zeroed and the data stored in non-volatile memory is restored.