Arc fault detector responsive to patterns in interval to interval change in integrated sensed current values

Abstract

The arc fault detector analyzes the pattern in the sequence of counts of increasing or decreasing intervals in the integrated current for patterns characteristic of an arc fault. In an AC system, the interval may be a full cycle, or, in an alternative embodiment, the positive and negative half-cycle integrated current changes are determined separately and then interleaved before calculating the change count. When a pattern characteristic of a phenomenon other than an arc fault is detected, the counting sequence is reset in order to avoid nuisance tripping.

Description

technical field [0001] Embodiments of the present invention are directed to devices that detect arc faults from characteristic disturbances in the load current, while avoiding unnecessary tripping due to load current disturbances produced by other phenomena. Background technique [0002] Arc fault detectors for AC and DC power systems typically monitor the load current for random disturbances characteristic of such faults. However, there are many "normal" events that can cause disturbances in the load current, which must be distinguished from arcing to avoid nuisance tripping. Some such events are: interruption of load current due to temperature switches such as irons, pancake tins or oven thermostats, operation of dimmers (dimmers) especially when settings are changed, capacitive running of electric motors, operation of compressors start, wait. [0003] A number of techniques have been proposed for distinguishing arcing from other load current events. US Patent No. 5,933...

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There is also the challenge of simplifying technical approaches that could potentially reduce the cost of arc fault detectors

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