An arc fault is a high power discharge of electricity between two or more conductors. The arc faults of our concern occur
in major electrical distribution systems. While an arc fault may be initiated by a low power arcing fault (a few amps), a true
arc fault will rapidly increase in current up to several hundred amps or even thousands of amps. An electrical switchboard seven
feet high, three feet wide, four feet deep, containing several hundred pounds of metal conductors and supports can, in a few
seconds, be reduced to an empty shell.
The chance of Arc Faults in electrical switchboards can be reduced by proper design, but this only helps new designs. What
can be done about existing switchboards? We have developed an Arc Fault Detection System (AFD) that can detect arcs quickly
enough to prevent major damage to the switchboards. Our Continuous Thermal Monitoring System (CTM) can prevent Arc Faults due to
overheated connections. These AFD/CTM Systems can be economically installed into existing switchboard. These systems have
hundreds of system years of successful operation with no false tripping of breakers. These systems have been used extensively by
the US Government to protect vital electrical distribution systems.
The Johns Hopkins University Applied Physics Laboratory has spent 22 years investigating the causes and effects of arcing
faults within electrical switchboards. We have conducted over 2000 arcs at power levels from a few kilowatts to over 20
megawatts. This site will describe out test facility and test methods. We will discuss how our results have led us to develop
the AFD/CTM family of sensors and systems and how they can be applied to the protection of power generation facilities and power
sensitive facilities such as hospitals, semiconductor manufactures, and other large scale electrical users.