Interesting problem. So the volt/ohm meter reads no shorts in the wiring, sounds like component troubleshooting is in order....
If I read the problem correctly, the 30a fuse blows immediately as soon as the battery is connected. IF thats correct I suggest the following:
Disconnect both leads to the generator and ensure that they do not touch each other nor any other surface.
With the battery positive disconnected, install a smaller amp fuse, 10, 20 etc., it doesn't matter for this test as the engine won't be started and the charging system won't be operating.
Connect the battery, does the fuse blow?
If yes, the problem isn't with the generator continue component troubleshooting to the regulator and associated wiring.
If no, you've got a problem either with the generator or wiring to it, troubleshoot accordingly.
IF you try this, check back with your results.
re. the linked manual, I'm going to continue to read the opening section that describes electric theory, I kinda dig such compositions....
