This may be due to a short circuit in the generator.
Due to insulation aging and long-term overload, the circuit forms a short circuit state if the fuse is plugged in, it will cause burnout.
Inspection method: Remove the thicker wire from the back of the generator, install the insurance, and rub the newly removed wire against the terminal. Normally there will be no sparks. sparks, there is a short circuit in the generator.