An apparatus and method for detecting arc faults that have reduced
susceptibility to nuisance tripping. The apparatus includes a current
sensor, an input sense circuit, an arcing sense circuit, a power supply,
a tripping (firing) circuit, a processor, and an electromechanical
interface. The current sensor monitors a power input comprising an AC
current, and provides high frequency components of the. AC current to the
input sense circuit. The input sense circuit filters and rectifies the AC
signal, and provides the rectified signal to the arcing sense circuit.
The arcing sense circuit provides a voltage level accumulated over a
predetermined time period, and digital signals indicative of possible
electrical arcing occurring during the sampling period, to the processor.
The processor measures the voltage level, stores information relating to
measured voltages and the digital signals, and processes the stored
information using one or more algorithms, thereby determining whether the
signals resulted from an arc fault or a nuisance load. In the event the
signals resulted from an arc fault, the processor activates the firing
circuit to trip the electromechanical interface, thereby interrupting the
power output to the load.