The single line diagram of a lossless system is shown in the figure. The system is operating in steady-state at a stable equilibrium point with the power output of the generator being , where  is the load angle and the mechanical power input is . A fault occurs on line 2 such that the power output of the generator is less than  during the fault. After the fault is cleared by opening line 2 , the power output of the generator is . If the critical fault clearing angle is  radians, the accelerating area on the power angle curve is ________times  (rounded off to 2 decimal places).

A generator feeds power to an infinite bus through a double circuit transmission line. A 3 phase fault occurs at the middle point of one of the lines. The infinite bus voltage is 1 pu., the transient internal voltage of the generator is 1.1 pu. & the equivalent transfer admittance during fault is 0.8 pu. The 100 MVA generator has an inertia constant of 5 MJ/MVA & it was delivering 1 pu power prior to the fault with rotor power angle of 30°. The system frequency is 50 Hz.   

The initial accelerating power (in pu) will be

A generator feeds power to an infinite bus through a double circuit transmission line. A 3 phase fault occurs at the middle point of one of the lines. The infinite bus voltage is 1 pu., the transient internal voltage of the generator is 1.1 pu. & the equivalent transfer admittance during fault is 0.8 pu. The 100 MVA generator has an inertia constant of 5 MJ/MVA & it was delivering 1 pu power prior to the fault with rotor power angle of 30°. The system frequency is 50 Hz.   
If the initial accelerating power is X pu, the initial acceleration in , and the inertia constant in MJ-sec/select deg respectively will be

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

A generator delivers power of 1.0 p.u. to an infinite bus through a purely reactive network. The maximum power that could be delivered by the generator is 2.0 p.u. A three phase fault occurs at the terminals of the generator which reduces the generator output to zero. The fault is cleared after second. The original network is then restored. The maximum swing of the rotor angle is found to be electrical degree. Then the rotor angle in electrical degrees at t = is

A synchronous generator is connected to an infinite bus through a lossless double circuit transmission line.  The generator is delivering 1.0 per unit power at a load angle of 30° when a sudden fault reduces the peak power that can be transmitted to 0.5 per unit.  After clearance of fault, the peak power that can be transmitted becomes 1.5 per unit. Find the critical clearing angle.

A synchronous generator, having a reactance of 0.15p.u, is connected to an infinite bus through two identical parallel transmission lines having reactance of 0.3p.u. each. In steady state, the generator is delivering 1p.u. Power to the infinite bus. For a three-phase fault at the receiving end of one line, calculate the rotor angle at the end of first time step of 0.05 seconds. Assume the voltage behind transient reactance for the generator as 1.1p.u. and infinite bus voltage as 1.0p.u.

A loss-alternator supplies 50 MW to an infinite bus, the steady state stability limit being 100MW. Determine if the alternator will remain stable if the input to the prime mover of the alternator is abruptly increased by 40 MW.
(Yes=1/No=0)

A generator is supplying 1 per unit power to an infinite bus through the system shown in figure. Following fault at F, circuit breakers  and  open simultaneously. The  relationships in per unit are given by

Pre-fault condition:

During fault condition:

When  remain closed:

After  open:

Calculate the critical angel  before which breakers

 and  must open so that synchronism is not lost.