I would think frying a transformer or circuit board would happen a lot quicker than what it would take to cook a wire.
That being said, I believe that a breaker is not sufficient enough to protect equipment and/or equipment components. By the time the breaker is tripped the damage has already been done to such sensitive devices. Am I wrong?
seaton: you are correct. For a non-motor circuit, one-time fuses will 'blow' at any excess current flow, without delay. One-time fuses would be more appropriate to protect circuits that do not involve any type of 'starting' currents. Like control circuits, electronic circuits, etc.
Breakers & time-delay fuses are meant to protect motor circuits, primarily, because of their being 'inverse-time' devices.