A power transmission line feeds input power at $2.3 \mathrm{~kV}$ to a step down transformer with its primary winding having 3000 turns. The output power is delivered at $230 \mathrm{~V}$ by the transformer. The current in the primary of the transformer is $5 \mathrm{~A}$ and its efficiency is $90 \%$. The winding of transformer is made of copper. The output current of transformer is _________ $A$.