Current transformer datasheet: confusion on turns ratio vs. max. rated currents
The DS says the rated input is 0 to 100 amps and independantly (on a seperate line) it says the rated output is 0 to 50 mA. You should take the turns ratio as being 1:1800 as stated in the DS and not assume that at full rated primary current (100 amps) the device will output 50 mA.

Magnetic core saturation (or rather the onset of core non-linearities) will take the maximum current down a shade or two from 55.5 mA to 50 mA. You could reasonably expect that with a primary current of  50 amps the output will be much closer to 1:1800 than at 100 amps primary current.