Question

A.)Engineers are tasked with calculating the dimensions of a transmission line from a power plant to a city 100 km away. The power plant outputs 765,000 V, and the transmission line must transport a minimum of 500,000 A of current. An intern looks up the value of resistivity from a database with the value of ?=1.29 ×10−8 Ω?. What is the diameter the wire the engineers need to use? Show work.

B.) The intern was in the wrong database and used the value of the resistivity for copper measured at

at -40°C in Alaska. Using the temperature-dependent equation for resistivity:

?= ?0[1+ ?(?−?0)]

Where α is the increase in ? per degree Celsius, having a value of ?=3.8 ×10−3 to calculate the value of ρ at 20°C for this transmission line. Show your work

Answer 1

m. (A)= 100 km = 1x105 m V = 765,000 V I - 500,000 A 1:29 X10 am a ( R. I uk 11 I d? 5 ♡ v pl A v 8 l 4 fl Td²/4 715000 4 X 129 X 10 x 10 500ooo 3.14 (22) 4 X 129 X 10 x 500 3:14 X 765 d = 3.20 x 10-2m 2 3 d? 8 a (B) :$ = [1+2 (7-To)] P = 1.29x10* ®[1 + 3-8 x16(20-1-90)] = 1:29x10@[1 +0.2287 8 = 1.58x10-8 rom