Electricity: electrical systems and devices – Safety and protection of systems and devices – Feeder protection in distribution networks
Reexamination Certificate
1999-06-21
2001-03-13
Sherry, Michael J. (Department: 2836)
Electricity: electrical systems and devices
Safety and protection of systems and devices
Feeder protection in distribution networks
C361S065000, C361S086000, C361S104000, C340S638000, C340S652000, C307S039000
Reexamination Certificate
active
06201675
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention is directed, in general, to power electronics and, more specifically, to a monitoring system for a power distribution system and a method of operation thereof.
BACKGROUND OF THE INVENTION
Power distribution equipment is commonly employed in power stations and power plants to deliver power to connected loads. Classically, the systems of this nature consist of a power distribution bay that receives power from a source and distributes that power to the loads by way of output power feeds. Circuit protection devices (e.g., fuses, circuit breakers), located within the bays, protect the loads from excessively high currents and voltages. Once a load is connected to one of the feeds, current flows through the circuit protection device of the output power feeds and to the load.
As with most electronic power supply equipment, it is advantageous to efficiently make use of the power distribution equipment. In order to maximize the use of the equipment, it is preferable to ascertain a utilization of the power distribution system. The utilization may be determined by comparing the portion of the equipment and circuits under use to the total circuit capacity of the power distribution system.
Presently, operators monitor the current flowing into the various power distributions bays to determine the utilization of the bay in relation to its total capacity or ampacity. In other words, the common practice is to monitor the current capacity of the bays under use. Unfortunately, this method is generally deficient in that monitoring current capacity is inaccurate and, more specifically, it does not supply adequate information as to the actual number of power feeds that are being used. Rarely does a bay exhaust its current capacity. Rather, the bay will employ all of its power feeds long before reaching its current capacity limit. Therefore, monitoring current capacity does not adequately measure the number of circuits under use in light of the total circuit capacity of the power distribution bay.
Accordingly, what is needed in the art is a monitoring system for a power distribution system that more accurately determines a circuit utilization thereof and overcomes deficiencies of the prior art.
SUMMARY OF THE INVENTION
To address the above-discussed deficiencies of the prior art, the present invention provides, for use in a power distribution system having first and second output power feeds having corresponding first and second circuit protection devices associated therewith, a monitoring system and a method of monitoring a utilization of the power distribution system. In one embodiment, the monitoring system includes: (1)first and second status sensors that sense statuses of the first and second circuit protection devices, respectively and (2) a controller, coupled to the first and second status sensors, that employs the statuses to determine a loading of the first and second output power feeds and calculates a utilization of the power distribution system based on the loading.
The present invention recognizes that monitoring the statuses of the circuit protection devices associated with respective output power feeds provides a reliable indicator of the use of the output power feeds of the power distribution system. The controller of the present invention employs the statuses to more accurately calculate the utilization of the individual output power feeds and, ultimately, of the entire power distribution system.
In one embodiment of the present invention, the power distribution system includes a plurality of output power feeds having corresponding circuit protection devices. The monitoring system is adapted to sense statuses of a plurality of circuit protection devices. The controller employs those statuses to determine a loading of the plurality of output power feeds and calculate the utilization of the power distribution system based on the loading.
In one embodiment of the present invention, the controller includes a decoder and a digital-to-analog converter (DAC). Those skilled in the art understand that alternate embodiments may include either the decoder or the DAC, but not necessarily both. In yet another embodiment, the controller may include a switch decoder, decoder and a DAC. The broad scope of the present invention, however, is not limited to any specific controller.
In one embodiment of the present invention, the first and second circuit protection devices are selected from the group consisting of a circuit breaker or fuse. Those skilled in the art recognize that other circuit protection devices are well within the broad scope of the present invention.
In one embodiment of the present invention, the controller is embodied in a sequence of instructions executable on the processor of a general purpose computer. Alternatively, the controller may be embodied in dedicated or hardwired discrete or integrated circuitry.
In one embodiment of the present invention, the statuses include first and second voltages across the first and second circuit protection devices, respectively. Those skilled in the art understand that in alternate embodiments, the statuses of the first and second circuit protection devices may be currents or other operational characteristics associated with the respective circuit protection devices or the output power feeds.
The foregoing has outlined, rather broadly, preferred and alternative features of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for designing or modifying other structures for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention in its broadest form.
REFERENCES:
patent: 5856711 (1999-01-01), Kato et al.
Lucent Technologies - Inc.
Sherry Michael J.
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