Q4. A synchronous generator is connected directly to an infinite bus. The voltage of the infinite bus is 15kV. The excitation of the generator is adjusted until the equivalent field voltage Ef is 14kV. The synchronous reactance of the machine is 5?. Compute the following: ( 10 points ) (a) The pullover power (b) The equivalent excitation voltage that increases the pullover power by 20%.

Q5. A 100 MVA synchronous generator is connected to an infinite bus through a transmission line. The infinite bus voltage is 15kV and the equivalent field voltage of the machine is 14kV. The transmission line inductive reactance is 4? and the synchronous reactance of the machine is 5?. ( 10 points ) (a) Compute the capacity of the system. (b) If a 2? capacitor is connected in series with the transmission line, compute the new capacity of the system.

Q6. A synchronous motor excited by a 5kV source has a synchronous reactance of 5?. The motor is running without any mechanical load (i.e the output real power is zero.). Ignore all losses and calculate the equivalent field voltage Ef that delivers 3MVAr to the source. Also draw the phasor diagram. ( 10 points )