A generator is connected to a synchronous motor through a transformer. Reduced to the same base, the pu sub transient reactance’s of the generator and motor are 0.15 pu and 0.35 pu respectively, the leakage reactance of the transformer being 0.1 pu. 3 phase fault occurs at terminals of the motor when the terminal voltage of the generator is 0.9 pu and the output current of the generator is 1 pu at 0.8 pf lag load. Sub transient current fed by the generator in pu is ______