Table 430.52 Time-Delay Fuse Size.

[Skokian]

If your measured current running is 11.78 I suspect the FLA it's quite a bit bigger than that.
No one designs a load EXACTLY at 100% of the motor capacity. Most likely 11.78 is about 80% of the FLA. Unless (as I mentioned before), there's something else wrong there. if the FLA nameplate is 10 some and you're drawing 11.78(especially with a higher voltage), either the design was bad (putting more load on the motor) or something else besides what's supposed to creates an additional load(bad bearings, bad valves on the compressor, belt/s too tight? I assume this is a belted compressor??? a belt that's too tight definitely will put a lot more load on the motor, especially at start up)

I've learned the hard way, that these compressors often run their motors well into their service factors. This is also common practice with fire pumps. Note that the compressor is a tank mounted one and runs well under one minute to build the pressure from 40 to 50 psi, which are the cut-in and stop set points.