I have a post war ZW transformer with a fuse between the transformer and the rails. What amp fuse would be appropriate so that it doesn't get blown a lot, but still provides protection to my newer electronic locomotives. The 10 amp fuse I am using gets blown to often.
Ditto on needing to find the underlying cause. Unless you are running multiple engines on one circuit, a ten amp fuse should not be blowing in normal use. I use five amp circuit breakers on each of my circuits, and rarely if ever have them trip under ordinary use.
Speaking of which, I think the relatively slight extra cost of circuit breakers is well worth what you have to pay to never again have to replace fuses. If you have expensive electronics on board your rolling stock, the instant-action circuit breakers are well worth the money, but since I just run PW trains, the cheap thermal breakers I used have so far done fine, at a fraction of the cost of the better versions.