I've done that before:
http://www.seventransistorlabs.com/Fuse/index.htmlFrom what scant little info there is in the article, it sounds like it's comparable, i.e., a fast-acting electronic switch. Unfortunately this isn't very useful for mains applications where surge loads are a necessary requirement.
They
may be handling mains voltage surge. SiC is available into the kV range, though you still have the Vds-Rds(on) tradeoff that all MOSFETs have*, so they probably need quite a lot of die area to keep resistance and dissipation reasonable.
*I don't remember if they're doing SuperJunction designs in SiC, but that would be important in a switch like this. The functional difference is, older generation VDMOS scaled as Vds ~ Rds(on)^2, i.e., really terribly (double Vds --> quadruple Rds(on) for the same die area), whereas SJ is proportional, so the power switching capacity scales with die area, more-or-less independent of Vds.
They're definitely
not handling fault current as a linear regulator. The energy handling of semiconductors is just pitiful. More likely they'd dump the excess into a MOV stack.
My electronic fuse, does just what it's asked to do: actively limit current in the domain of ~us, and turn off (in ~us to ~ms) when the current goes above the setpoint. Unfortunately it's rather annoying because most DC loads have more capacitance than this thing can charge, even if you rapid-fire restart (keep tapping the 'on' button). So it nuisance trips, and it's really hard to use.
So, I fear that a semiconductor "breaker", of useful size, will suffer a similar fate. At least with conventional loads. Maybe with
all smart loads (with inrush protection or precharge circuits, and PFC, and..), it would be feasible, but that's asking a
lot even for a new built home in a trendy place.
So, later I made this,
which has a much more respectable capacity: 30V 20A nominal rating (maximum 40V drop), active current limit for 150ms duration, and thermal protection. That's enough charge (a whopping 3 coulombs) to start pretty much anything (nominally, 100mF at 30V?). It's also bidirectional so it can be used on bipolar DC sources, batteries (no worry about limiting charge or discharge currents), that sort of thing; but, probably not AC, due to the capacitance.
The main downside is the amount of noise thrown off (the filtering is not exactly FCC Part 15 grade), but it's only generated during fault conditions so it's not a big deal. I mean, that and the cost.
Since it does have capacitors and inductors inside, it's not as ideal of a switch as the other one, but you can't have everything.
Mechanical switches are
damned hard to beat, offering huge on/off ratios even at high frequencies, and handling lots of joules of make/break energy (depending on design, of course -- mains breakers are designed to start an arc and launch it into a heatsink, until zero crossing; doing that at 10kA and hundreds of volts, for about 10ms, is a lot of energy!).
Going back to the breaker, I would think it much more likely that it's just a pair of solenoids, a bit of thinky-stuff, and an utterly conventional (mechanical) breaker. That's entirely possible, and affordable, with off-the-shelf parts, and doesn't expose any semiconductors* to mains surge or fault conditions. It doesn't sound nearly as exciting, which may be as much of a reason not to discuss its internal workings.
*Well, still the solenoid drivers, but that's a lot easier to manage.
Tim