Square D Company

Lee D Wallis

Michael W Pyle

Robert A Kennedy

Ronald L Farrington

David C Carlson

Donald T McComas

A voltage isolation circuit. The input voltage Vin is connected to a primary winding of a transformer Tthrough a current limiting resistor R. Ris preferably sized such that the current flow in the primary at nominal input voltage is approximately 1 milliamp. Transformer Tis wound as a current transformer with a fixed ratio between the primary and secondary windings. Thus, when 1 mA flows in the primary winding, 1 mA will also flow in the secondary winding. An inverting operational amplifier will continuously attempt to drive its inverting input to a zero potential through resistor R. The voltage at Vout produced by the op-amp is a faithful replica of the voltage at Vin, but scaled according to the values selected for Rand R

Apparatus and method for voltage sensing in electrical metering systems

A metering unit, located in a distributed power network carrying a power-related waveform, comprises a sensor, a generator, and a memory. The sensor senses power-related parameters associated with the power-related waveform. In response to the sensor, the generator generates and transmits data representative of the power-related waveform. The memory is a sector-erasable flash EEPROM having stored therein programmable logic and main functionality firmware for execution by the generator. The logic is programmable by a user and executable by the generator to increase operations performed by the metering unit.

Metering unit with integrated user programmable logic

The present invention provides an arrangement for automatic selective circuit interruption in response to detection of a fault in a multi-phase distribution system feeding a plurality of network branches. The arrangement includes a plurality of line monitoring devices which are programmed to alarm a control station in response to detection of a fault in the system. In response to being alarmed by one or more line monitoring devices, the control station activates a specialized signal generator which produces a specialized signal along one of the lines of the multi-phase system. Each line monitoring device is co-located with and communicatively coupled to a circuit interrupter which, when actuated, prevents the flow of current in lines of the system positioned downstream from the actuated circuit interrupter. Each line monitoring device automatically actuates the coupled circuit interrupter within a prescribed period of time following detection of the specialized signal. By making the prescribed actuation time period longer for upstream circuit interrupters than downstream circuit interrupters, the network may continue providing power less an isolated section having the ground fault. The one or more line monitoring devices which detect the specialized signal inform the control station of the location of the fault.

Apparatus and method for detecting a fault in a distributed line network

Firmware is downloaded to a metering unit located in a distributed power network carrying a power-related waveform, where the metering unit senses power-related parameters associated with the power-related waveform and generates and transmits data representative thereof. The metering unit is provided with a sector-erasable flash EEPROM having a first section for storing main functionality firmware and a second section for storing boot code. The boot code includes a reset portion for resetting the metering unit and a firmware update section for downloading external firmware to the first section. The firmware update section includes a writing routine for writing the external firmware to the first section. The metering unit is also provided with a volatile RAM. The external firmware is downloaded to the first section of the EEPROM by executing the firmware update section. While executing the firmware update section, the writing routine is copied to the RAM and executed therefrom to write the external firmware to the first section of the EEPROM.

Metering unit with downloadable firmware

A circuit monitoring system for a distributed power network employs waveform capturing techniques for efficient and highly accurate monitoring. The system includes a plurality of circuit monitors and a control station, which is coupled to each of the circuit monitors via a multi-drop communications link. Each of the circuit monitors is disposed adjacent an associated one of the branches in the network for sensing power parameters in the branches and for generating and transmitting data representing the power parameters to the control station The control station is used for generating monitoring commands to each of the circuit monitors to provide the system with full system control and evaluation capability. Each of the circuit monitors also includes EEPROM memory for storing and retaining operational data, sent from the control station, in the absence of power. This allows a microcomputer in the circuit monitor to read the retained data for analyzing the sensed power parameter.

Reconfigurable circuit monitoring system

A circuit monitoring system for a distributed power network employs waveform capturing techniques for efficient and highly accurate monitoring. The system includes a plurality of circuit monitors and a control station, which is coupled to each of the circuit monitors via a multi-drop communications link. Each of the circuit monitors is disposed adjacent an associated one of the branches in the network for sensing power parameters in the branches and for generating and transmitting data representing the power parameters to the control station. The control station is used for generating monitoring commands to each of the circuit monitors to provide the system with full system control and evaluation capability. The system is capable of simultaneously sensing the waveform at each branch and sampling the waveforms for a predetermined number of sample points over an integral number of cycles so as to provide an efficient yet accurate implementation.

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Murfreesboro, TN, United States of America

Lee D Wallis