A $2200$ V$,2600kW,735rpm,50Hz,8$ pole, $3-$phase squirrel cage induction motor has following parameters referred to the stator:

$R_s=0\mathrm{.}075,R_r^{\text{'}}=0\mathrm{.}1,x_s=0\mathrm{.}45,x_r^{\text{'}}=0\mathrm{.}55.$ Stator winding is delta connected and consists of two sections connected in parallel. Calculate starting torque and maximum torque as a ratio of rated torque, if the motor is started by star delta switching. What is the maximum value of the line current during starting?