Assume a three-phase, unity power actor load of 100 MVA with VLL of 69 kV is connected to a source through the below network. Convert the two impedances to per unit. Use a per unit three-phase 100 MVA base, a line-to-line 138 kV voltage base on the left side of the transformer and a line-to-line 69 kV voltage base on the right side.

answer: the exterior temperature of commercial jet planes as they leave the stratosphere and return to the ground increases steadily.

explanation:

the lower most layer of atmosphere is troposphere which extends from 0 to 12 km above the surface of the earth. the temperature initially decreases as distance is increased from the earth's surface. commercial jets fly in lower part of the stratosphere. the stratosphere extends upto 50 km. the temperature in stratosphere starts rising again due to presence of ozone which traps the uv rays.

thus, when the planes leave the stratosphere and return to the ground, the exterior temperature increases steadily.