Blown fuses are caused by excessive current flow, usually as a result of a short circuit - I won't claim to be familiar with an 87 Samurai, but, I have no recollection of a 30A fuse in the alternator circuit, and I'm a couple of miles away from my manuals, so I can't check.
Find yourself a diagram and see which circuits are powered from the fuses that are blowing, check those for a short circuit - if there is a fuse in the alternator circuit that keeps blowing, there is a strong probability that the alternator itself is defective.