well i think that the best way is to put fusess to th esecondary and a thermal fuse(if thats what is called, the type of fuse that burns at a given temperature and a given current also, they look something like capacitors, the olt type ones) in the contact with the primary, i usually use 125 or 150 degrees celsius fuses/1.....2.5 amps,
and use fuses for the secondary, to protect the seconary....but usually doesnt the primary burn down?
i mean for not such great power transformers, a few amps... :?: