Figure 3 shows a DC distribution system with two loads conne

Figure 3 shows a DC distribution system with two loads connected to the source. The resistance of the cable is given as 0.01ohm per 100m. The 30A load is fed from the source or points AF and the 20A load is fed from the first load or points BE from the figure below. Calculate: The voltage across the first load (LOAD 1=30A).

Solution

the resistance of the cable is given as 0.01 ohms per 100 metres.

the resistance for go and return of the cable =0.01*2 per 100 metres=0.04 ohms per 100 metres

resistance for 200 metres=0.02*2=0.04 ohms

current through AB=30+20=50 amps

voltage drop across line AB=0.04*50=2 volts.

the voltage across the first load (load 1=30 amps)=120-2=118 volts.