DIRECT CURRENT ARC FAULT DETECTOR AND CIRCUIT INTERRUPTER, AND METHOD OF DETECTING AN ARC IN A DIRECT CURRENT POWER CIRCUIT

摘要

A direct current arc fault detector includes a first current sensor sensing an alternating current component of current flowing in a DC power circuit; a second current sensor sensing a DC component of the current; and a bandpass filter filtering the sensed AC component. A demodulating logarithmic amplifier includes an input of the filtered AC component, and an output. An integrator or minimum detector includes an input connected to the amplifier output, and an output. A processor repetitively inputs and then resets the integrator or minimum detector output, and determines an arc when, for a predetermined time: the sensed DC component being greater than a first predetermined value, and a present value of the integrator or minimum detector output being greater than or different from a previous value of such output by more than a second predetermined value, or the present value being greater than a third predetermined value.

主权项

1. A direct current arc fault detector for a direct current power circuit having a current flowing therein, said direct current arc fault detector comprising:
first detection circuitry structured to sense an alternating current component of the current flowing in said direct current power circuit; second detection circuitry structured to sense a direct current component of the current flowing in said direct current power circuit; and a processor structured to periodically repeat an interrupt routine until an arc fault is detected, wherein the interrupt routine, when executed by the processor, causes the processor to:
(a) determine if a present value of the direct current component is greater than a first predetermined value;(b) determine if a present value of the alternating current component is greater than a first predetermined threshold multiple of a first previous value of the alternating current component, wherein the present value of the alternating current component and the first previous value of the alternating current component are separated by a first predetermined amount of time;(c) increment a first arc fault counter if (a) and (b) are true and otherwise decrementing the first arc fault counter;(d) determine that the arc fault is present and ending the interrupt routine if the first arc fault counter is greater than a first threshold value.