Fuse for solid state relay protection - semiconductor I2T or standard

"Steve"

A 10amp SSR will typically withstand 100 to 150 amps for one cycle - enough time for a fast HRC fuse or magnetic breaker.

Possibly add series resistor into the circuit or a non-saturating inductor of 1.5 mH to get the short circuit current down.

..... Phil

Perhaps the "relay" would turn into a very nice ultra low R wire instead of opening..

Do consider the consequences of various failures. Blown fuse, down for an hour. Blown semis, down for a day or two. Blown motor, down for weeks. Or maybe completely different. But only you and your customer really know the application and the consequences, that is part of the engineering.

Monitor the desired switched line in question. Monitor the voltage on that shunt. If the max value is reached, "OPEN" the low voltage DC excitation line that activates the relay, NOT the line experiencing the high current.

In other words, turn off the relay, instead of attempting to open the line the relay switches with yet another set of contacts of some sort (a breaker).

The relay is already the switch/circuit/line breaker.

correct., assuming its contacts are rated to break the fault current (and it's poor engineering if they aren't)..

"lurch"

It will take unit the end of the half cycle ( ie the current must fall to near zero) for the triac to commutate off - so the full fault current will have to be tolerated for that long at least. Good bye 10 amp triac.

For your idea to work, impedance must be added in series with the load to limit the fault current to a safe value. Plus the circuit must latch off and be manually reset when the fault is cleared.

Much more practical to just use an up-rated SSR, add a bit of series impedance and fit a fast acting HRC fuse.

Works for professional lighting dimmers.

.... Phil