I'm building a device that uses a microcontroller to control 15 solenoids via a preexisting multichannel DC solid state relay board. When all is working as intended, at most one solenoid will be actuated at a time, and each actuation consists of a 100 millisecond 24V/3.5A pulse.
I'm looking for a way to insure that a solenoid won't be overheated even if there's a software fault that causes an output pin to remain high, and consequently cause the SSR to remain open, driving the solenoid.
So my question is this: is using a a slow-blow fuse in series with the shared 24V supply a prudent way to protect against burning up solenoids?
If so, what specs should I use for the fuse? Should I just take the the I^2 * T value (1.2) and double it?
If there's a better way to do this, I'd love to hear it.