New England Power Service Company

Thomas Industries, Inc.

Lawrence J Stratton

Dennis C Jeffreys

Reed H Johnston

Albert W Welz, Jr

David M Fischer

William H Henrich

Thomas E Dean

Herbert E Pietsch

An electronic frequency inverter circuit receives input electrical power at a lower frequency and energizes a load circuit including gaseous discharge lamps in a range of higher frequencies. First and second semiconductors are operated alternatively by a logic circuit in current mode control such that the switches operate at the high frequency range and the frequency of current in the load circuit varies as the magnitude of said source voltage varies. The load circuit has an impedance which varies with frequency such that the peak amplitude of the load current remains substantially constant despite variations in the magnitude of said source voltage to achieve a desirable crest factor for the lamp current. A high current limit circuit rapidly turns off the switches when excessively high current begins to flow through the switches. Low voltage is supplied in port from the high frequency current. Normal operation is ensured during start-up, for reduced line voltage and for a semiconductor chip embodiment.

High frequency ballast for gaseous discharge lamps

A method and an apparatus for communicating over electric power lines in a direction from load to source is disclosed. The power line voltage wave is loaded in a predetermined pattern to produce a corresponding pattern of signaling currents at a receiving site. Detection of the signaling current is accomplished in the preferred embodiment by integrating the current in the phase or the neutral of the feeder that serves the signaling site during predetermined time windows which are synchronized with the power line voltage wave. The current integration is performed in accordance with a detection algorithm to accumulate principally the current differences that are attributable to the signaling currents while in the presence of steady and transient currents on the feeder.

Method and apparatus for communication over electric power lines

A method and apparatus for transmitting intelligence over a carrier wave are disclosed in which a signal waveform is added to a carrier wave to produce a composite wave having a recognizable pattern of variations in intervals that are defined by preselected locations in the composite wave. The pattern of variations in intervals resulting from the addition of the signal waveform to the carrier wave represents at least a portion of the intelligence to be transmitted over the carrier wave. The variations in intervals defined by the preselected locations in the carrier waves are detected and the detected interval variations are converted into a signal which has a characteristic that is a function of the recognizable pattern of interval variations. In the preferred embodiment the intelligence is transmitted over an electric power distribution network utilizing the alternating voltage therein as the carrier wave.

Method and apparatus for transmitting intelligence over a carrier wave

A cycloconverter apparatus and method is disclosed in which the cycloconverter works into an active load. The cycloconverter is connected between an external power source and a load so that the load current flows through the cycloconverter. In the preferred embodiment, the cycloconverter is used to impress a signaling voltage waveform upon the voltages of the three phases of an electric power distribution feeder. This voltage is impressed by injecting it between the common point of the wye-connected secondary of the substation transformer and the grounded neutral that serves all phases of the distribution feeder. The neutral current of the distribution feeder flows through the cycloconverter. Protective by-pass circuitry is provided to maintain the integrity of the neutral path in the event of a phase-to-neutral short circuit or a failure of the cycloconverter.

Cycloconverter apparatus and method for working into an active load

A method and apparatus for transmitting intelligence over a carrier wave are disclosed in which a signal wave is combined with a carrier wave to produce a composite wave having a recognizable pattern of variations in intervals that are defined by preselected locations in the composite wave. The pattern of variations in intervals resulting from the combination of the signal wave with the carrier wave represents at least a portion of the intelligence to be transmitted over the carrier wave. The intelligence is extracted from the composite wave for subsequent utilization. In the preferred embodiment the intelligence is transmitted over an electric power distribution network utilizing the alternating wave thereon as the carrier wave. The variations in intervals defined by the preselected locations in the composite wave are detected and the detected interval variations are converted into a signal which has a characteristic that is a function of the recognizable pattern of interval variations.

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Lexington, MA, United States of America

Lawrence J Stratton