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DC, Interrupted By Simon Morrow
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s John Shen likes to say, Thomas Edison was right—he was just 100 years or so too early. In the late nineteenth century, Edison said that direct current (DC) is a better form of electricity than alternating current (AC). Shen, the Grainger Professor of Electrical and Computer Engineering at Illinois Institute of Technology, agrees. “DC has always been more efficient and stable compared to AC electricity,” says Shen. “Unfortunately, at the time, people didn’t know how to raise the voltage level in DC for long-distance transmission, but they did for AC. That’s why AC won the war. But that’s changed.” Around a decade ago, Shen started to see signs that emerging technologies would benefit from greater use of DC power, so he set out to eliminate one key remaining barrier: a lack of effective, cost-efficient DC circuit breakers. “You can buy an AC circuit breaker from a Home Depot for $5 or $10 that is very reliable, but you can’t use those for DC power networks,” Shen says. Since Shen started working with DC electricity, the Advanced Research Projects Agency Energy (ARPA-E), of the United States Department of Energy, has awarded him $2.65 million to develop DC fault protection technology and has started a new funding program dedicated to developing medium-voltage DC circuit breakers, credited in part to his work. 12
Illinois Tech Research
A prototype of the iBreaker, a 380 volt solid-state circuit breaker for DC data centers
