Emerson Electric Company

Distribution Control Systems, Inc.

Sioe T. Mak

Ray C., Jr. Hatton

David S. Takach

Sioe T Mak

Kevin J Franzen

Ray C Hatton

David S Takach

Richard L Maginnis

Brian C Ramey

Jr Hatton Ray C

A quick response system incorporated in a TWACS for mapping an outage in an electrical distribution system without having to continuously poll the electrical meters connected to the system. In a primary embodiment of the invention when a fault is sensed to have occurred, the amplitude of the fault is measured to determine if the fault is a medium voltage fault, or a low voltage fault. The pattern of the fault signature and change in load, both before and after the fault, are examined to determine what protective device was triggered by the fault. Using this information, and knowledge of the number and location of electrical meters connected in the distribution system, a population of meters to be polled is determined. By polling the identified population, a map of the extent of the outage is readily determined, and the time to respond to the fault and restore service is reduced.

Intelligent fault detector system and method

An interface circuit (10) for use with electronic metering equipment (E) to provide a linear output response to an AC or analog input. An air core transformer (12) has a first coil or winding (12a) connected to a load (L). An AC current I.sub.LOAD is produced by the load and is coupled to a secondary coil or winding (12b) of the transformer. The transformer has an air core rather than a ferromagnetic core so to have no saturable core. Because no load is drawn by transformer coil, the voltage across a terminal of the coil equals the EMF induced in the coil. The EMF, in turn, equals the mutual inductance of the coils multiplied by the rate of change of magnetic flux linkages over time. The output from the transformer is applied as an input to an operational-amplifier (16) which has a high input impedance. Further, the amplifier is a low drift amplifier which performs a linear amplification of the input signal provided thereto. In certain embodiments, a pair of similar amplifiers are used and the secondary winding of the transformer is a tapped winding so to accommodate both a low range and a separate high range of inputs. The output from the operational amplifier is supplied to an analog-to-digital converter (18) so a digital output is supplied to the metering equipment. If the tapped coil, dual amplifier arrangement is used, the resolution requirements of the converter are lower than if the single amplifier circuit configuration is used. Use of the interface circuit eliminates the DC component of the sensed voltage and provides a linear response for the metered AC input to the measuring equipment.

Linear alternating current interface for electronic meters

A two-way communication system (TWACS) used with an electrical power distribution network N. The TWACS provides both outbound and inbound messages to and from remote network locations. A method of detecting and decoding unsolicited inbound messages from remote locations first involves generating the message in response to a time independent event occurring at the remote location. Formation of the message includes both generating a series of message bits, each of which has a prescribed format, and affixing a preamble to the front end of the message which comprises a plurality of bits arranged in a predetermined pattern. The message is then transmitted over any one of a plurality of communication channels n normal used for two-way communications. Since the event triggering the unsolicited inbound message is independent of time, the time of transmission is random. The message is received at a receiving site, receipt of the message including receipt of the bits comprising the prefix together with bits comprising the message. The bits forming the preamble are detected, their detection signalling the fact an unsolicited message is being received. Preamble bit detection also initiate synchronization of operation of the TWACS to decode the contents of the message.

Method of receiving unsolicited messages on an electrical distribution

Signals carried inbound on an electricity distribution network are detected by extracting electrical current information from a waveform of the electricity distribution network, and digitally filtering the electrical current information, thereby forming a digital waveform, to extract signal information contained in the electrical current information. A reference waveform is constructed from a portion of the digital waveform, and the signal information is detected by comparing portions of the digital waveform with corresponding portions of the reference waveform.

Inbound communications using electricity distribution network

A communication system uses the current waveform of an electricity distribution network as a carrier, the signal being present as current pulses around four predetermined zero crossings. The current waveform is sampled around the voltage zero crossings to obtain a time-ordered set of waveform values. The ordered waveform values for each bit are examined to determine if the values fall within preset criteria indicative of a stable carrier. When the ordered waveform values for a particular bit all fall within the preset criteria, that particular bit is identified as a good bit. When at least some of the ordered waveform values for a particular bit fall outside the preset criteria, that particular bit is labelled as suspect. The ordered values of each suspect bit and of adjacent bits are tested to determine whether four successive values meets the preset stability criteria, and whether the four successive values indicating a stable carrier include at least two succesive values from the suspect bit. If the carrier stability test is passed, the binary value of the suspect bit is based upon the successive carrier stability indicating values from the suspect bit. Otherwise the suspect bit is labelled as uncorrectable.

Carrier stability erasure filling system for communications over

A communication system with six simultaneous independent inbound channels is disclosed which uses the voltage waveform of an electricity distribution network as a carrier. The manner in which the inbound channels are identified as well as how various sets of such independent channels can be found is disclosed. Identification of sets or groups of such independent channels involves identifying all potential channels and calculating the detection algorithm for each. Pure pulse patterns for binary '1's for each channel are then multiplied by the detection algorithms for every channel to generate a matrix whose elements include the application of all the detection algorithms to all the aforementioned pulse patterns. Examination of qualifying elements of the matrix allow the identification of sets of mutually non-interfering channels.

Simultaneous inbound multi-channel communication system using

Waveforms are derived from each primary of a multi-phase electric distribution system, which derived waveforms include at least a carrier component. At least some of which derived waveforms include a signal component. The waveform of one of the primaries is adjusted in amplitude and phase so that the carrier components of the derived waveforms substantially cancel when the waveforms are summed together.

Method and apparatus for extracting inbound information generated

Outbound signals carried over an electric power network are detected and crosstalk is rejected by sampling the waveform in three segments of each cycle. In the first segment valid signals are always absent. Valid signals appear at the same time in both the second and third segments. Sample waveform values from alternate half cycles are compared to detect differences indicative of outbound signal information. The energy in each of the three segments is compared with an energy threshold for that segment and a cycle under test is rejected when the energy in the first segment exceeds the threshold for that first segment. A cycle under test is also rejected if the energy in the third segment greatly exceeds the energy in the second segment. Signal detection thresholds for both signal strength and energy in the segments are set recursively using actual samples acquired at the outbound detection site. These thresholds are sensitive to dynamic network changes.

Outbound detector system and method

A method and apparatus for transmitting intelligence over a carrier wave are provided in which a signal wave form is indirectly 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 wave form 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 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. In the preferred embodiment, the intelligence is transmitted over an electric power distribution network utilizing the alternating voltage thereon as the carrier wave. By indirectly adding the signal wave form to the carrier wave, a simplified modulation system and method is provided which can be adjusted to control the amplitude of the signal wave.

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Chesterfield, MO, United States of America

Sioe T Mak