a load taking 200A is supplied by copper and aluminium cables connected in parallel.the total length of conductor in each cable is 200m,and each conductor has a cross sectional area of 40 mm^2..the resistivity of copper and aluminium are 0.018 megaohmmeter and 0.028 megaohmmeter.
calculate:
a)the voltage drop of combined cables
b)the current carried by each cable
c)the power wasted in each cable

Question

a load taking 200A is supplied by copper and aluminium cables connected in parallel.the total length of conductor in each cable is 200m,and each conductor has a cross sectional area of 40 mm^2..the resistivity of copper and aluminium are 0.018 megaohmmeter and 0.028 megaohmmeter.
calculate:
a)the voltage drop of combined cables
b)the current carried by each cable
c)the power wasted in each cable

radar · Answer

Since the physical dimensions for the cables are similar, the amount of resistance for the cables will depend solely on the resistivity of the material with the copper carrying a larger amount of the current than the aluminum.  However, I don't have the the "know how"  to compute the individual resistances 40mm^2 vs circular mills etc.  However, .018 mega ohms per meter seems kind of high, are you sure that it isn't Ohms/meter??

anonymous · Answer

Actually the resistivity of copper is about 0.018 MICRO ohms-m. Just recall the formula for resistance of a piece of material given the length, cross-sectional area and resistivity, calculate the resistance of each conductor and solve the circuit as two parallel resistors connected to a current source of 200A.

radar · Answer

Thanks Bill_Bailey, I suspected that was incorrect resistivity value, big difference between microOhms and MegaOhms