Abstract: A current sensing device includes a secondary coil positioned within the curved portion of a U-shaped primary conductor or coil. The secondary coil is surrounded by a non-ferromagnetic metallic shield to prevent capacitive coupling between the windings of the secondary coil and other nearby metallic objects. A nonconductive material is integrally formed about the U-shaped conductor and provides a cavity for receiving the secondary coil an shield in a predetermined position with respect to the U-shaped conductor. A flux guide of ferromagnetic metal, formed in an elliptical-cylindrical shape, surrounds the U-shaped conductor and the secondary coil to provide a flux steering effect to steer flux around the secondary or pick-up coil. The current sensing device is useful in measuring current in electrical utility power monitoring or watthour meter applications.

Abstract: A current measurement circuit for an electrical energy meter of the type having an inductive current pickup which generates a signal proportional to the derivative of current with respect to time in an electrical power line. An underdamped integrator is provided which compensates for nonideal phase characteristics of the inductive current pickup including a phase deviation from 90.degree. at the nominal line frequency. The integrator has a transfer function with a magnitude peak at a frequency below the line frequency and with a phase shift deviating from 90.degree. at the line frequency.

Abstract: A watt-hour meter cover is provided which has an optical coupler including a conduit, lens, and means for engaging an external programmer/reader. The conduit is has improved signal transmission properties. The cover may be designed to disable test mode hardware when replaced after meter servicing. A battery access hatch and module with a reset and scroll actuator is installed through the cover.

Abstract: A time of use register for use in an electronic watthour meter is formed of a three piece interlocking construction without the use of separate fasteners or the use of tools for assembly. The TOU register includes a front cover, a rear cover and a resilient clip, each of these components having various features to provide firm containment of a PC board and an LCD within the register. The front cover includes a window within which the LCD is positioned and a connector slot within which a resilient electrical conductor strip is situated. The electrical conductor strip provides communication between the PC board, which has a contact array at one edge of the board, and the LCD array, which also has a complementary contact array at its upper edge. The rear cover encloses the rear and part of the sides of the TOU register and includes a number of stops for providing uniform pressure against the PC board to hold it in position.

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 modular strain relief device is plugged directly into an electrical connector location in the interior of a housing assembly, according to one embodiment of this invention. The body of the strain relief connector provides a surface around which a portion of the wire conductor is wrapped for additional strain relief. Arm-like projections keep the wire conductors in close proximity to the body of the strain relief connector. An integrally molded locking structure attached to one end of the body of the strain relief connector allows it to be locked into an unused plug-in connector location inside the housing assembly. A bundle of wire conductors is secured to the flexible body of the strain relief connector with a cable tie placed through an aperture in a molded projection located at one end of the body of the strain relief device.

Abstract: A time of use register for use in an electronic watthour meter is formed of a three piece interlocking construction without the use of separate fasteners or the use of tools for assembly. The TOU register includes a front cover, a rear cover and a resilient clip, each of these components having various features to provide firm containment of a PC board and an LCD within the register. The front cover includes a window within which the LCD is positioned and a connector slot within which a resilient electrical conductor strip is situated. The electrical conductor strip provides communication between the PC board, which has a contact array at one edge of the board, and the LCD array, which also has a complementary contact array at its upper edge. The rear cover encloses the rear and part of the sides of the TOU register and includes a number of stops for providing uniform pressure against the PC board to hold it in position.

Abstract: A watt-hour meter cover is provided which has an optical coupler including a conduit, lens, and means for engaging an external programmer/reader. The conduit has improved signal transmission properties. The cover may be designed to disable test mode hardware when replaced after meter servicing. A battery access hatch and module with a reset and scroll actuator is installed through the cover.

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: A time registering electric energy meter for measuring usage of an AC energy quantity includes primary and secondary DC power supplies and a microprocessor, having a realtime clock maintained by the 60 Hz AC energy quantity, for maintaining realtime and for generating AC energy usage information determined by a number of time-related events. The meter further includes power outage recovery circuitry for measuring the duration of an outage of the AC energy quantity and for restoring the amount of lost realtime to the realtime clock of the microprocessor upon resumption of the AC energy quantity. The power outage recovery circuitry includes apparatus for iteratively updating the microprocessor realtime clock while comparing the updated realtime with the clock calendar times of the number of time-related events to account for the occurrence of such events during the outage of the AC energy quantity.

Abstract: An electronic demand register includes a microprocessor including a program clock for performing timekeeping functions for the register. A power supply connected across the AC voltage source provides power to the microprocessor through a voltage regulator. The program clock is maintained by the line frequency of the AC source. Electronic circuits are provided for calibrating the program clock to be compatible with either a 50 Hz or a 60 Hz line frequency. A detection signal corresponding to the line frequency is generated by a line frequency detector circuit in the power supply. A reference signal is generated by a quartz crystal clock. A frequency comparator circuit includes a microprocessor program that measures the time period between detection signal pulses. This time period is compared to the known period of a 50 Hz or a 60 Hz signal and respective counters are incremented accordingly.

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: A voltage transducer in a watthour meter, for sensing AC line voltage across a load, includes a current transformer having its primary winding connected in series with a current-limiting resistor across the AC source. The transformer includes a secondary coil and a tertiary coil. The current through the secondary coil represents the sensed voltage and is signal conditioned through an integrator circuit for input to a solid-state watt transducer chip. An active circuit is connected across the tertiary coil, with an output feeding a compensating current into the input of the secondary coil. The active circuit includes an RC network at the output of the tertiary coil for providing a loop stability. A first non-inverting op amp amplifies the voltage output from the RC network to provide a phase correction, adjustable by a replaceable resistor connected between the inverting node of the first op amp and an electrical ground.

Abstract: A solid-state watthour meter for registering AC electrical energy consumption by a load connected to a source of AC load current and AC line voltage includes a voltage sensing transducer for producing a signal corresponding to the line voltage and a current sensing transducer for producing a signal corresponding to the load current. A solid-state measurement circuit receives the voltage and current signals as its inputs and produces an output signal corresponding to the AC electrical energy consumption of the load. A power supply, including a regulator circuit having a calibration resistor, provides a DC voltage to the measurement circuit. The DC voltage across the regulator circuit is dependent on the impedance of the calibration resistor. The measurement circuit includes apparatus for relating the registration of the meter to the DC supply voltage. The calibration resistor is readily removably electrically connected in the regulator circuit.