American Science and Engineering, Inc.

Neil H Jagoda

Klaus Kubierschky

John S Ballas

Adrian G Roy, Jr

A remote load controlling apparatus receives a disconnect signal on a line that is filtered and voltage limited. This disconnect signal sets a flip-flop which enables an oscillator and a solid-state switch. The enabled switch energizes a relay to disconnect the load from electric service. A counter counts the output of the enabled oscillator and provides a flip-flop reset signal after a local time delay that is determined by a particular incremented count state of the counter. The reset flip-flop disables the oscillator and solid-state switch to de-energize the relay and reconnect the load to electric service. The flip-flop may also be reset by a remote signal to disable the oscillator and solid-state switch and reconnect the load before the counter is incremented to its particular incremented count state. A second counter and a second solid-state switch may be added to ensure that the load is connected to electric service if a component of the apparatus should fail. The second solid-state switch is enabled by the pulse output of the enabled oscillator and is disabled when the oscillator stops generating pulses. The second solid-state switch is connected in series to the first solid-state switch and the relay is energized only when both solid-state switches are enabled. The second counter is provided to enable the oscillator on the leading edge of the disconnect signal and disable the oscillator after a time delay.

Remote load controller

A remote meter-reading system interrogates meter stations over power lines and receives encoded meter readings over the power lines in synchronism with the power line frequency by superimposing a digitally modulated signal over the 60-Hz power frequency. The central control station transmits at a data rate of 60-baud and receives at a data rate that is 60-baud or a submultiple thereof, to reduce the demands on the remote meter station transceiver as compared to those on the central control unit transceiver. The bit clock at the central control unit and the meter stations is derived from the 60-Hz power line phase available at each station. Each meter station achieves message synchronization by continuously monitoring the data bit stream for a preset synchronization code and thereafter treats the following 21 data bits as address and function codes. Each meter station that is addressed responds at the data rate designated by the function code by transmitting with a message including the address and function bits for comparison at the central control station with that originally sent to facilitate error detection, and the meter reading encoded according to an error detecting code. A binary data bit is represented by quadrature phase lead and lag relative to reference phase of the character.

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Framingham, MA, United States of America

Neil H Jagoda