Fuses are normally used on the 12 volt side of life in RV's breakers on the 120vac side.
My guess is this fuse is the converter's reverse polarity fuse, it can blow if the batteries are very low and the converter is bigger than the fuse, THERE MAY BE A 2nd FUSE you need to replace at the same time.
Many converters have 2 or 3, usually 30 amp, fuses that protect them from batteries installed backwards.
however my battery bank can, and has, sucked 99 amps off my Xantrex prosine when I accidently disconnected my converter (My primary converter is a PDI 9180 with wizard, it is a plug in model, and sometimes it becomes unplugged, it is usually middle of the night when I figure it out and invoke the back up converter (The charger module in the prosine) Imagine these batteries are that low and I plugged in the 80 amp Intella POwer with only 60 amps of fuses.. Something going pop and quickly.
I think this is what is happening to you, I think the converter is bigger than the fuse. and with the batteries low.. fusees poppis to make a fake latin phrase out of it.
