Researchers at Oak Ridge National Laboratory (ORNL) have developed a new circuit breaker that operates hundreds of times faster than traditional models, clearing a path for a safer and more efficient US power grid. 

"The ORNL team developed medium-voltage circuit breakers capable of handling increasing levels of direct current at a lower cost," said the research team.

The device interrupts currents of 1,400 volts in less than 50 microseconds—a speed essential for protecting next-generation direct current (DC) power systems.

"Until now, semiconductor breakers have been too expensive to either compete economically with mechanical breakers for AC, or to facilitate expanded use of DC grids," stated the researchers in a press release.

"No type of commercial breaker can handle DC above 2,000 volts, and most can't achieve half that."

Making high-power DC grids feasible

This breakthrough makes the widespread use of high-power DC grids feasible. The ORNL team has already proven the technology can be scaled by linking breakers in a series.

"ORNL researchers designed solutions and tested them in a series of breakers operating up to an 1,800-volt testing capacity," added the press release. 

They are now working toward systems that can handle the 10,000 volts required by future energy demands from applications like AI data centers.

The team built the breaker using an inexpensive and robust semiconductor called a thyristor.

"Thyristors are affordable enough to make semiconductor-based switches competitive for the first time," explained the press release.

While affordable, thyristors have a key limitation: they cannot be easily switched off.

Preventing explosive electrical arcs

The ORNL engineers solved this by designing a novel external circuit that forcibly stops the current, making the technology economically competitive for the first time.

"We selected a base technology that was robust, efficient and inexpensive," noted lead researcher Prasad Kandula.