Given the following information:
A wye-connected generator driving a transmission line with a delta-connected load. The generator is rated at 20 MVA at a phase voltage of 200 K. V. A transmission line with an impedance of 1 + j3 ohms/mile. A load with a rated power is 6 MVA with a power factor of 0.8 lagging and a rated line voltage of 120 KV.
(a) What is the equivalent, per-phase impedance of the load?
(b) How long can the transmission line be and still have the load be at its ratings?

To save energy, the air supply to a 2000 ft office has been shut off overnight and the room temperature has dropped to 40°f. in the morning, the thermostat is reset to 70°f and warm air at 120 f begins to flov in at 200ft'/min. the air is well mixed within the room, and an equal mass flow of air at room temperature (changing with time) is withdrawn through a return duct. the air pressure is nearly 1 atm everywhere. ignoring heat transfer with the surroundings and kinetic and potential energy effects, estimate how long it takes for the room temperature to reach 70°f. plot the room temperature as a function of time.