AFCI technology is a new and exciting technology that provides protection against dangerous arcing conditions that can result in fires. Arcing conditions are inherently chaotic and non–linear. They may be sporadic and intermittent depending on the nature of the fault, the condition or age of the wiring and connections, or other circuit parameters. Arcing conditions tend to worsen over time due to arc path carbonization.

Based on proprietary algorithms, Sensata Technologies is developing a family of AFCI products that can mitigate hazardous arc–fault conditions and improve safety. We have developed and licensed intellectual property that not only detects high–level arcing conditions but is also sensitive enough to detect low level series arcing without causing a nuisance trip.


There has been a substantial amount of research conducted to understand and characterize arcing phenomena, and to qualify and quantify conditions specific to end applications. Several key characteristics of reliable arc–fault detection include:

•	Ability to differentiate between normal load current and arc current
•	Insensitivity to cross–talk signals
•	Ability to sense a small arc current in the presence of large load currents
•	Insensitivity to RFI / EMI
•	Immunity to normal load start–up transients
•	Fail–safe
•	High reliability — no false or nuisance trips

Sensata Technologies’ intellectual property addresses these characteristics and provides an AFCI solution that can be tailored for residential, aerospace, and other electrical circuit applications.


Sensata Technologies has identified several key principles of arc detection that are incorporated into the AFCI sensing circuit of the products we provide. For AC circuits, we use algorithms that detect arcing currents that are uncorrelated with line voltage, while rejecting correlated currents. Other algorithms sample the AC waveform and integrate the data to determine whether undesired arcing conditions are present. For DC circuits, the AFCI algorithm responds to the chaotic spectral density within a defined detection band. Whether AC or DC, the AFCI algorithms contain a number of key features that are critical to reliable and nuisance–free performance while providing superior levels of AFCI protection. These key features include:

•	Eliminates loss of protection due to ground returns past the monitoring point
•	Does not require a dedicated return line to monitor ground fault performance
•	Can detect low current series arcs caused by loose or damaged connections
•	Ground fault protection may be added if desired
•	Can detect arcs over considerable distances
•	Performance is not degraded by most intervening filters
•	May be augmented with time domain parameter monitoring
•	Detection is not dependent on radiated energy
•	Displays excellent cross–talk and discrimination ability