Not a subject that will be taught on a RV tech forum. But I’ve worked on many electrical devices that have breakers and fuses in parallel. The electrical code is clear when this configuration can be used.
Simply put, it has to be approved at the factory because we can’t expect all Electricians in the field to understand the electrical design theory or have access to specification to each type and make of breaker or fuse.
An interesting thing to note is, most high current fuses have multiple parallel elements which basically is paralleling fuses in one case. Not to be confused with timed delayed dual element fuses.
The design and use of an over current device is like everything in this world, is controlled by economics first. For example; I have fuses that cost over $10,000 and breakers that have to be re-condition for around $30,000 after so many times they are opened and closed and sooner if they trip under a fault condition. Every year I have to explain to a Company VP with a Business Degree why I need so much money in my budget.
I believe that the OP is trying to make a decision on using an auto resetting breaker, although he is thinking of safety first, he states that his electrical knowledge is limited. They’re reasons why one 40 amp over current device cost more then another, but putting expensive racing tires on my 4X4 doesn’t make it go faster or improve the ride. I believe that auto resetting over current devices are used in circuits that are prone to known momentary spikes in over current from a known electrical load (motors for one that is designed to take theses over currents). Or for safety reasons like a feed circuit to a hospital or power grid, can you imagine laying in a hospital bed and waiting for an Electrician to reset a breaker or change a fuse!!
The OP is thinking of putting an auto resetting breaker on an electrical device (Inverter) that doesn’t do well in over current events (electronics). If there is a fault, the breaker he posted will keep re-closing till something gives and if no one is there to possibly get hurt, the cost of repair will most likely be more then the price he would be saving on fuses.
