TRUE INVERTER POWER

True inverter power=KVA Rating of Transformer * Power Factor.

For its losses, since it not a true sine wave, tita=90/2=45 degree.
Therefore, Power Factor=COS45=0.7071

True inverter Power=Transformer KVA RATING * COS45.
For 1KVA,
True inverter power=1000*COS45
True inverter Power=700W the require fuse rating will be
I=700/230=3.0A.