Abstract: A solid state electrical meter incorporates the ability to support two-way radio, dialback telephone and CEBus personal LAN. These three communications media require different protocols to meet their respective requirements. Embedding multiple protocols within the meter controller makes the device extremely flexible for current and future applications.

Abstract: A method for measuring an AC current in a conductor in which a DC current also exists includes the steps of (A) obtaining a first AC current measurement; (B) obtaining a measure of a power factor, fundamental frequency component, and second harmonic component; and (C) adjusting the first AC current measurement in accordance with an error value to obtain a corrected current measurement. The error value is determined as a function of the power factor, fundamental frequency component, and second harmonic component.

Abstract: An automatic meter reading system utilizes repeater technology to access hard to read meters within a fixed network structure. The components of the radio system that are needed for two-way communications are employed without adding significant cost to the meter. Using this approach, each meter in the network has the ability to repeat messages as required.

Abstract: A very low cost method of driving the coil of a meter disconnect switch utilizes the 60 Hz signals from an existing power supply rectifier to generate properly phased gate drive signals to SCRS, with only one stage of isolation.

Abstract: Methods and apparatus for establishing communications between electrical and electronic devices utilizing existing power signal distribution networks are disclosed. In such methods and apparatus the transmitting and receiving components of such devices are coupled between line and ground. Such coupling is achieved utilizing a coupler, a first frequency reactive device, such as a drain coil or inductor, connected in series with neutral and a second frequency reactive device, such as a capacitor connected between neutral ground. For use with existing electronic equipment, an adaptor for coupling the communications signal to a power signal distribution network is also disclosed.

Abstract: Apparatus and methods are claimed for detecting tampering with a load management terminal, wherein the terminal has a load control relay coupled to a power line for selectably decoupling the load from the power line. One embodiment of the claimed apparatus for detecting tampering comprises a current sensor coupled to the load control relay for sensing whether load current is flowing through the load control relay contacts when the contacts are closed. A timer is provided for measuring elapsed time during which no current is sensed flowing through the closed contacts. An indicator provides an indication of tampering when the elapsed time measured by the timer exceeds a pre-determined time limit. Preferably, in this embodiment, the current sensor comprises a voltage detector coupled to the control coil of the relay for detecting whether an AC voltage has been induced in the control coil by the load current.

Abstract: A power distribution line communication system for, and method of, reducing effects of signal cancellation at locations along the distribution line due to standing waves caused by reflections of a carrier signal impressed on the distribution line. A same outgoing data signal is modulated on each of a plurality of carrier signals having different frequencies. The carrier signal frequencies are selected such that all of the carrier signals will not experience signal cancellation at a same location on the distribution line. The modulated carrier signals are simultaneously impressed on the distribution line for transmission to remote locations, thereby ensuring reception of the outgoing data signal at each remote location.

Abstract: Apparatus for coupling a high voltage power distribution system (2) to a communications device (14), the system (2) carrying electrical energy in the form of a high voltage at a power frequency and communications signals at a frequency higher than the power frequency, composed of:a capacitive power factor adjustment unit (4) connected to the distribution system (2) to correct for baseline loading and inherent reactance of the distribution system (2);a blocking unit (6) connected between the adjustment unit (4) and ground, the blocking unit (6) having an impedance which varies directly with frequency such that the voltage across the blocking unit (6) at the power frequency has a value substantially less than the high voltage at the distribution system (2) and the communications signal voltage across the blocking unit (6) has a value only slightly less than at the distribution system; anda signal coupling unit (10,12) having a low impedance at the communications signal frequency and connected between the blocki

Abstract: A tuned circuit is provided for connection to a transmitter of a power line communication system. The tuned circuit comprises components selected to provide a low impedance path to ground for a power line communication signal of a preselected frequency. When the transmitter is not in the process of transmitting a power line communication signal, it causes a shorting switch to be closed which shorts a secondary winding of a transformer of the tuned circuit. Therefore, during periods of time when the transmitter is not transmitting power line communication signals, spurious signals on the power line are diverted to ground and not permitted to travel to remote receivers connected to the power line distribution system.

Abstract: A transceiver provides a relatively constant output voltage from its linear amplifier by providing both current and voltage feedback to its operational amplifier. The present invention utilizes common components for both transmitting and receiving and provides an apparatus which can both transmit and receive power line carrier signals which can be used to communicate digital data through phase modulation of the carrier signal. The transceiver of the present invention can be operatively connected to a microprocessor through appropriate filtering and switching.

Abstract: A signal bypass apparatus for a power line distribution switch incorporates two portions that are electrically connected together in parallel with a power line switch. Each portion comprises a transformer that is connected electrically in parallel with an inductor. A capacitor is connected between the transformer and the inductor of each portion and the assembly is connected between one side of a power line distribution switch and ground. The other portion of the bypass apparatus is similarly configured and connected between the other side of the power line distribution switch and ground. In one embodiment, the bypass apparatus is electrically connected to a transceiver.

Abstract: A transceiver is provided with both voltage and current coupling to a three phase transmission line system. Each phase conductor is coupled to a common point which is connected in signal communication with an input to a receiver. Another input of the receiver is coupled to the neutral conductor of the power line system by an H-field coupler. A signal coupling unit is associated with the voltage couplers between the common connection point and the first receiver input. The receiver is provided with the capability of comparing the voltage signal with the current signal and selecting the stronger of the two. Therefore, the transceiver of the present invention is less adversely affected by standing wave problems since the voltage and current signals are out of phase and voltage nodes are associated with current antinodes and vice versa. Therefore, regardless of the location along the standing wave that the transceiver is located, the best signal available will be used for demodulation purposes.

Abstract: A current limiter is provided which responds to the magnitude of the output current signal from a power amplifier. A full wave rectified signal is provided in response to the magnitude of the current output signal and is used as an input to a comparator. The other input of the comparator is a voltage reference signal that represents a maximum desired current level for the output current signal of the power amplifier. When the output current signal exceeds its reference level, a signal is provided which is used as an input to an exclusive-OR gate which has, as its other input, a modulated square wave signal. The effect of the exclusive-OR gate is to notch the square wave modulated signal in such a way so as to alter its shape. The altered square wave carrier signal causes the MOSFETs of the power amplifier to switch on and switch off at additional occurrences which has the effect of reducing the maximum current level of the output current signal being output by the power amplifier.

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: A transistor base drive circuit achieves optimum base current levels to avoid unnecessary transistor power dissipation by including means for diverting excessive base drive from the transistor base to the transistor collector. A capacitor in series with the transistor base decreases switch transition time. Increasing capacitance of the capacitor results in a decrease in transistor saturation voltage, thereby decreasing power dissipation in the transistor.

Abstract: The switching intervals for the power transistors in a three-phase inverter are generated by a microprocessor. DC content control is provided separately for each phase by modulation of the duration of the switching intervals through adjustment of the length of the sequences of instructions carried out by the microprocessor.

Abstract: An alternating current power controller is provided that employs DC transistor switching for subcycle switching capability and to eliminate problems associated with SCRs and furthermore provides internal elements for generating the required DC control power from the AC source whether the AC load is on or off.

Abstract: A relay coil circuit with a switching regulator for coil current to maintain, after closing, a sufficient holding current by the inductance of the coil acting as a current source without supply current.

Abstract: An arc quenching circuit senses initiation of an arc across the contacts of a contactor, commutates a capacitor discharge to the contacts that brings the contact voltage to zero for arc extinction and promptly recharges the capacitor to enable reoperation.

Abstract: A direct current, high voltage, switching voltage regulator for generating a low voltage, low current supply referenced to the positive side of the input voltage is provided while maintaining operation over an extended voltage input range with maximum efficiency, that is, low power loss and heat dissipation.