Update: Promethean devices has been sold. Its technology is now used by investors keeping an eye on the flow of energy throughout the country to predict the price of electricity. I think it is still used by a few utilities and I personally wish it will be marketed again for its original purpose.
---------------------------------------------------
Promethean Devices is a startup company based in South Carolina. Founded by Steve Syracuse, the company addresses the need for maximizing the power transport capability of high voltage power lines. In the language of the electric utilities, the Promethean sensor system determines, in real time, the ampacity of power lines. The benefit of knowing the ampacity will be felt during high power consumption periods (usually in August when air conditioning loads peak), as this is when the utilities occasionally "turn off" neighborhoods because the power lines might be overloaded. The Promethean sensor system would tell the utility whether the line is actually overloaded, or that it can carry more power. The sensor works by detecting the magnetic field from the power lines and determining the sag of the lines (the lines sag as they carry more current and heat up). (Increasing sag means that the clearance between the ground and the power line is diminishing.) The amount of line sag is used to compute the line temperature, and ultimately the ampacity.

Credit for the invention goes to the various co-authors. Steven Syracuse set the stage. He identified the need and the feasibility of ampacity determination. Peter Halverson (myself) conceived of the magnetic field approach to sag and current determination. Fred Tesche did electromagnetic analysis of the sensor concept. Roy Clark analyzed the conversion of sag (or clearance) measurements to temperature and ampacity. Fred Barlow was instrumental in creating the sensor prototype and propelling the company forward. Finally, Steven Syracuse, indefatigable company founder, continues to be the moving force behind Promethean Devices.
.