| 摘要 |
An arcing fault detector band pass filters the ac current in a protected circuit to generate a sensed current signal with pulses having an amplitude related to the step increases in current produced each time an arc is struck. The envelope of this pulse signal is tracked by a first, slow tracking circuit or envelope detector having a first, long time constant and a second, fast tracking circuit having a second, shorter time constant. When the second tracking signal generated by the second tracking circuit falls below a predetermined fraction of the first tracking signal of the first tracking circuit, a charge pulse modulator generates a pulse of a size which is a function of the amplitude of the most recent pulse in the sensed current signal. When a time attenuated accumulation of the charge pulses maintained on an integrating capacitor reaches a preselected level, an output circuit generates an arcing fault indication.
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