$($i$)$ As shown in Fig. $1,$ a synchronous genera$$or feeds bus $1$ of a system. A power network feeds bus $2$ of the system. Buses $1$ and $2$ are connected through a transformer and a transmission line. Per unit reactances of the various components are:

Generator $($connected to bus bar $1)$:

$0\mathrm{.}25$

Transformer:

Transmission line:

$0\mathrm{.}12$

The power network can be represented by a generator with a reactance $($unknown$)$ in series. With the generator on no load and with $1\mathrm{.}0$ pu voltage at each bus under operating condition, a three$-$phase short circuit occurring on bus $1$ causes a current of $5\mathrm{.}0$ pu to flow into the fault. Determine the equivalent reactance of the power network.