If you know the impedance of the transformer you can do a rough calculation as follows.
Most transformers have an impedance of 4 to 5 %.
Continuous output current of transformer is 104 Amps.
if impedance is 4% then 100/4 = 25 * 104 gives 2600 Amps.
allowe for a factor of two so a 6 kA braker would be fine.
The 10 kA you have should have no problem at all braking a fault.
Then other factors which will reduce the available fault current are the length of the cables from the Transformer to the braker, the actual loading at the time a fault occurs conditions of the terminations, overhead underground etc.
edited for typo's (ROD)
[This message has been edited by RODALCO (edited 08-11-2006).]
