What happens when the humble circuit breaker becomes a computer

I have been writing a lot lately about a big trend in the energy world, namely the decentralization of the energy system. Almost all electricity used to be generated at large power plants and carried over long-distance, high voltage transmission lines before it was dumped into local distribution grids. These days, a small but growing fraction of it is generated, stored, and managed within the distribution grid itself.

This is accomplished by an array of distributed energy resources (DERs) — from solar panels to batteries to EVs — that are increasingly tied together and coordinated by software. And as more and more cars and buildings are electrified, there will be more DERs to juggle. Keeping distribution grids running smoothly will become a bigger and bigger challenge.

Even as distribution grids struggle to digitize, much of electrical infrastructure remains resolutely stuck in the 20th century, manual and analog. Take the humble circuit breaker for example. Every electrical device in the country is connected to the grid through one. Its job is simply to cut off the flow of current to an electrical circuit in the case of a fault or surge, to prevent overloaded lines, sparks, and fires.

If you’re a homeowner, you’re probably familiar with the experience: the power in the kitchen suddenly goes out, you struggle briefly to remember where your electrical panel is, you find it and squint with your flashlight at the tiny, inscrutable labels, finding the one that says “KIT” and manually flipping the switch. Then you yell, “Did that do it?”

When you think about how you interact with almost every other system in your day-to-day life, it seems primitive.

The circuit breaker goes digital

The basic design of the circuit breaker has not changed appreciably since Thomas Edison came up with the idea toward the end of the 19th century. It’s still an electromechanical switch that manually breaks an electrical connection, separating two wires.

Circuit breakers don’t just drag building owners into their basements to squint at electrical panels, they’re slow enough that they still allow lots of short circuits and arc flashes, which can destroy property and even kill people. “Each year in the United States, arcing faults are responsible for starting more than 28,000 home fires,” says the non-profit Electrical Safety Foundation International, “killing and injuring hundreds of people, and causing over $700 million in property damage.”

Plus, mechanical circuit breakers are static. One rated for 30 amps will always and only handle 30 amps. They are ill-suited to the constantly shifting, evolving world of DERs.

For years, researchers and entrepreneurs have pursued something better, and in January, a small company in North Carolina called Atom Power became the first to pass the necessary tests to bring one to market: a solid-state digital circuit breaker.

Solid state means no moving parts, with less maintenance, and a much longer life. In place of mechanical switches, current is interrupted by semiconductors, which means it happens at around the speed of light. Specifically, when triggered, a semiconductor-controlled switch trips in 3 microseconds, roughly 3,000 times faster than the fastest mechanical switch.

In this 2018 video, electrical engineer and founder Ryan Kennedy explains how Atom got there first. It has to do with manufacturing semiconductors out of silicon carbide (a mix of silicon and carbon, also known as carborundum) rather than silicon.

First, it enables the semiconductor to be six to 10 times smaller, allowing the products to mimic the size and shape of traditional breakers and electrical panels. Second, it is much more efficient than silicon, especially at high voltages, and unlike mechanical switches, its efficiency rises as voltage falls. And third, it is much more fault tolerant at high temperatures than silicon, allowing the product to pass strict testing by the Underwriters Laboratories. (UL, a consumer safety research laboratory, is approved by the federal government to set safety standards for a wide range of consumer products in the US and Canada.)

This suggests two things. First, Atom has pulled off something clever, with a fairly small team. Three cheers for American innovation! And second, competitors won’t be far behind. After all, silicon carbide isn’t patented. Other companies, big players, are already investing in their own digital circuit breakers. This is going to be a hot market in coming years.

So let’s take a look at digitally controlled electricity — what it can do and what it might enable.

Digitally controlled electricity is safer

First and most importantly, because semiconductors react so much faster than mechanical switches, they are much safer, effectively eliminating short circuits and arc flash, as demonstrated in this video:

(Every product looks cooler with a metal soundtrack.)

Digital circuit breakers can even anticipate and thwart faults before they happen. Faults are preceded by small disruptions in the electricity sine wave, and “since we’re sensing in the microsecond range and opening in the nanosecond range,” Kennedy explains, “you can interrupt that [fault] well before it propagates.” (Mechanical switches, on the other hand, don’t know that they need to trip until there’s a fault.)

Atom claims the Atom Switch is the fastest and safest circuit breaker in the world, capable of lightspeed interruption of currents up to 150,000 amps.

But controlling electricity digitally can do much more than solve common safety problems.

Digital circuit breakers are packed into panels that replace several other devices

In recent years, materials science and computing power have advanced enough to allow Atom to stuff a little computer into each breaker. Each has its own firmware, its own unique identity on the network, and a little e-ink display of its status (which works even without power).

The breakers are stacked into a panel that has roughly the shape and appearance of a normal electrical panel. Each panel contains a copy of Atom OS, the operating system that allows the breakers to be controlled through a user interface. Each panel is assigned its own IP address, so controlling it just involves logging on with a computer, iPad, or phone through a router. Importantly, because the firmware and OS are contained within the panel itself, it requires no external connection to the web (or any external server) to work. The building owner has total control.

As of now, Kennedy estimates that Atom Switches are two to five times the cost of conventional mechanical switches. But because the breakers are digitally controlled, they can accomplish tasks that used to require multiple pieces of equipment.

In big commercial facilities, conventional circuit breakers are surrounded by, to quote an IEEE Spectrum piece on Atom, “meters, load controllers, surge-protection devices, power-transfer switches, and demand management systems,” all of which require specialized equipment. The computers controlling digital switches can accomplish all those functions, thus replacing all that infrastructure.

Through their firmware, digital switches can meter power, dynamically control amperage based on load, and prevent surges and faults by specifying instantaneous, short-time, and long-time trip settings (along with a variety of other parameters I don’t begin to understand, but Atom assures me are of great interest to the people who manage these systems).

The OS also has contains built-in motor control (motor “soft-starting” is a big problem for commercial electrical systems, for reasons we needn’t get into), relay protections for over- or under-voltage events, and fast (80 microsecond) switching between power sources.

All these functions can be set remotely, put on a schedule, and programmed to react dynamically according to conditions.

All of that may sound like electricity-system jargon, but the point is that controlling power digitally enables a radical reduction of electrical infrastructure and simplification of electricity management. Finally, there’s an app for that.

Digitally controlled electricity could enable smarter distribution grids and more decentralized energy

Since they passed UL testing, Atom’s products have drawn investment from three of the four largest circuit breaker manufacturers: ABB, Siemens, and Eaton. For now, the company is going after commercial and industrial facilities with lots of high-value loads at stake. For instance, it has a whole brief on how buildings that manage multiple EV chargers — sure to be a growing category, including many office parks and parking garages — can use digital power management to balance out loads and distribute capacity (and eventually deal with vehicle-to-grid technology).

The market will begin among commercial and industrial customers, but if digital circuit breakers prove their value in the field, there’s no reason to think the market won’t scale up. As it does, costs will come down. It’s easy to envision all circuit breakers, through attrition, eventually going digital, though it’s impossible to predict how fast that might happen.

There are millions and millions of circuit breakers in the US. If every one of them becomes a self-aware, dynamically adapting, remotely controllable computer capable of linking up and coordinating with all the other computers, distribution grids will become much smarter and distributed energy resources (DERs) will be much easier to integrate and control.

I asked Kennedy if the same basic technology controlling a panel could be scaled up to support a microgrid or even a whole distribution system. The short answer, he said, is yes. He compared the modularity of the digital circuit breaker to the Tesla battery, which is the same basic thing in a sedan and a semi-truck. There are just more of them stacked together in the truck.

Same with digital electricity controls. “Our technology is not only scalable, but it’s also significantly easier and faster to scale than mechanical breakers today,” Kennedy says. “You could adapt and scale the technology for practically any power system.”

As I have written, one key aspect of the clean energy transition, one reason it’s likely to proceed faster than previous energy transitions in history, is that it won’t just be about switching out one set of machines for another. In large part, it will be about substituting intelligence for stuff — i.e., computing power for labor and material.

Computing power, which is always getting cheaper, will help determine how to maintain the same energy services with less labor and material, which are almost always getting more expensive. All analog systems will eventually go digital.

The digital circuit breaker is just one key step in the process of digitizing the electricity system. As software comes to control and distribute more power, AI, machine learning, and ubiquitous sensing will be put to use making the process more efficient, enabling the smart integration of local distributed energy resources. The result will be a smarter, cleaner, and more democratic grid.

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