Patent ID: 7400481
Filing Date: 2008-07-15
Classification: G01R,H02H

Abstract:
1. Arc fault detection apparatus, comprising: a power input; a processor integrated circuit (IC) including a first input, a second input, and at least two input protection diodes, the two input protection diodes being coupled to one another at a common node and connected in series between a supply voltage and ground, the first input being connected to the common node of the two input protection diodes; a differential voltage input sense circuit operative to sense at least one differential voltage (dv/dt) signal associated with the power input, and to provide the dv/dt signal to the first input of the processor IC; and a differential current input sense circuit operative to sense at least one differential current (di/dt) signal associated with the power input, and to provide the di/dt signal to the second input of the processor IC; wherein the two input protection diodes of the processor IC form a zero-crossing detector operative to detect zero crossings of the dv/dt signal, and wherein the processor IC is operative to measure the di/dt signal at times based on the detected zero crossings of the dv/dt signal, and to analyze the dv/dt signal and the di/dt signal based on at least one characteristic of the respective dv/dt and di/dt signals for determining whether the dv/dt and di/dt signal characteristics are indicative of an arc fault.