초록

A method and apparatus are provided for detecting the occurrence of arcing of a conductor by monitoring the current on an AC power line.

대표청구항 ▼

1. An arc fault detecting device comprising: at least one transformer adapted to generate a voltage based on a current present on a line conductor of an electrical wiring unit;a comparator configured to generate at least one signal based on the voltage generated by the at least one transformer;a fir

1. An arc fault detecting device comprising: at least one transformer adapted to generate a voltage based on a current present on a line conductor of an electrical wiring unit;a comparator configured to generate at least one signal based on the voltage generated by the at least one transformer;a first path configured to modify the at least one signal to represent the current present on the line conductor;a second path configured to modify the at least one signal to represent a pulse for each occurrence of a positive step change in the current as a function of time;a third path configured to modify the at least one signal to represent a pulse for each occurrence of a negative step change in the current as a function of time;a fourth path configured to modify the at least one signal to represent a voltage level indicating a broadband noise signal on the current present on the line conductor; anda controller in electrical communication with the comparator by the at least one of a first, second, third, and fourth path and configured to compare the at least one modified signal to a first waveform generated by the controller, the comparison between the at least one modified signal and the first waveform representing an absolute difference therebetween;wherein the absolute difference is analyzed by the controller, continuously and a half cycle at a time, by using at least one of a plurality of criteria. 2. The arc fault detecting device according to claim 1, wherein one criterion of the plurality of criteria relates to indicating arcing based on a condition selected from the following: if there are two peaks in the absolute difference within the half cycle;if the second peak of the two peaks of the absolute difference in the half cycle is lower than the first peak; andif half cycles having the two peaks within the absolute difference are surrounded by a period of one or more half cycles when a lower current flows. 3. The arc fault detecting device according to claim 1, wherein one criterion of the plurality of criteria relates to indicating arcing if two step changes of current occur in the half cycle where the first has a current function of time spike of a same polarity as the current and the second has a current function of time spike of opposite polarity to the current. 4. The arc fault detecting device according to claim 1, wherein one criterion of the plurality of criteria relates to indicating arcing by randomness in a time between current function of time spikes. 5. The arc fault detecting device according to claim 1, wherein one criterion of the plurality of criteria relates to indicating arcing by half cycles having two current function of time spikes surrounding a period of one or more half cycles when a much lower arcing current is flowing. 6. The arc fault detecting device according to claim 1, wherein one criterion of the plurality of criteria relates to indicating arcing when a high frequency noise (HFN) input signal is high between two current function of time spikes and is low during a remaining half cycle. 7. The arc fault detecting device according to claim 1, wherein one criterion of the plurality of criteria relates to indicating arcing if a HFN input peaks between two current function of time events. 8. The arc fault detecting device according to claim 1, wherein one criterion of the plurality of criteria relates to indicating arcing if a HFN follows a sine curve between two current function of time events. 9. The arc fault detecting device according to claim 1, wherein one criterion of the plurality of criteria relates to indicating arcing by half cycles having HFN signal characteristics surrounding a period of one or more half cycles when a much lower HFN signal is present. 10. The arc fault detecting device according to claim 1, wherein upon determination of an arc fault, the controller drives at least one output pin high. 11. A method of detecting an arc fault, the method comprising: generating a voltage based on a current present on a line conductor of an electrical wiring unit, via at least one transformer;generating at least one signal based on the voltage generated by the at least one transformer, via a comparator;modifying the at least one signal to represent the current present on the line conductor, via a first path;modifying the at least one signal to represent a pulse for each occurrence of a positive step change in the current as a function of time, via a second path;modifying the at least one signal to represent a pulse for each occurrence of a negative step change in the current as a function of time, via a third path;modifying the at least one signal to represent a voltage level indicating a broadband noise signal on the current present on the line conductor, via a fourth path;allowing electrical communication between the controller and the comparator by the at least one of a first, second, third, and fourth path;comparing the at least one modified signal to a first waveform generated by the controller, the comparison between the at least one modified signal and the first waveform representing an absolute difference therebetween; andanalyzing the absolute difference via the controller, continuously and a half cycle at a time, by using at least one of a plurality of criteria. 12. The method according to claim 11, further comprising indicating arcing based on a condition selected from whether: there are two peaks in the absolute difference within the half cycle;the second peak of the two peaks of the absolute difference in the half cycle is lower than the first peak; andhalf cycles having the two peaks within the absolute difference are surrounded by a period of one or more half cycles when a lower current flows. 13. The method according to claim 11, further comprising indicating arcing if two step changes of current occur in the half cycle where the first has a current function of time spike of a same polarity as the current and the second has a current function of time spike of opposite polarity to the current. 14. The method according to claim 11, further comprising indicating arcing by randomness in a time between current function of time spikes. 15. The method according to claim 11, further comprising indicating arcing by half cycles having two current function of time spikes surrounding a period of one or more half cycles when a much lower arcing current is flowing. 16. The method according to claim 11, further comprising indicating arcing based on a condition selected from whether: a high frequency noise (HFN) input signal is high between two current function of time spikes and is low during a remaining half cycle;a HFN input peaks between two current function of time events;a HFN follows a sine curve between two current function of time events; andhalf cycles having HFN signal characteristics surrounding a period of one or more half cycles when a much lower HFN signal is present.