Can we use a switch disconnector for the incoming of a panel knowing that it's fed directly from a generator?
The switch-disconnector cannot be used to protect generators because it does not offer short circuit protection. Therefore, for this case, 3 options are available:
Option 1, is to use a back-up protection (upstream) for the switch-disconnector (i.e: fuse) to offer short circuit protection.
Option 2, is to use a protection relay for generators along with the switch-disconnector (i.e: Sepam/MiCOM).
Option 3, is to use a circuit breaker instead of the switch-disconnector, and that's the RECOMMENDED solution.