Direct current electrical system arc detection apparatus and method

A method for detecting an arcing fault in a DC electrical system having a circuit protection system, the method of arc detection comprising the steps of:

• monitoring the DC electrical system with a superheterodyne circuit;
• generating an oscillator frequency which cycles between a low frequency and a high frequency, with an oscillator circuit coupled to the superheterodyne circuit;
• eliminating background and spurious noise with a comparator circuit coupled to the superheterodyne circuit and a reference voltage terminal;
• monitoring time of the arcing fault based on a signal from the comparator circuit with an arc timing monitor circuit;
• compensating for arcing drop outs based on signal from the arc timing monitor circuit with a compensating circuit;
• generating a further signal indicative of the arc fault if a predetermined time period is exceeded, with an accumulating circuit based on the signal from the compensating circuit;
• and,
• generating an arc signal to operate the circuit protection system, with a trip signal generation circuit based on the further signal from the accumulating circuit.

An arc detection circuit for detecting an arcing fault in a DC electrical system having a circuit protection system, the arc detection circuit comprising:

• superheterodyne circuit configured to monitor the DC electrical system;
• an oscillator circuit configured to generate an oscillator frequency which cycles between a low frequency and a high frequency, with the oscillator circuit coupled to the superheterodyne circuit;
• a comparator circuit configured to eliminate background and spurious noise, the comparator circuit coupled to the superheterodyne circuit and a reference voltage terminal;
• an arc timing monitor circuit configured to monitor time of the arcing fault based on signal from the comparator circuit;
• a compensating circuit configured to compensate for arcing drop outs when signal from the arc timing monitor circuit is received by the compensating circuit;
• an accumulating circuit configured to receive the signal from the compensating circuit and generate a further signal indicative of the arc fault if a predetermined time period is exceeded;
• and,
• a trip signal generation circuit configured to receive the further signal from the accumulating circuit and generate an arc signal to operate the circuit protection system.