A generator with constant 1.0p.u. terminal voltage supplies power through a step-up transformer of 0.12p.u. reactance and a double-circuit line to an  infinite bus bas as shown in Figure. The infinite bus voltage is maintained at 1.0p.u.  Neglecting the resistances and susceptances of the system, the steady state stability power limit of the system is 6.25p.u. If one of the double-circuit is tripped, the resulting steady state stability power limit in p.u. will be