6. Compare the total copper cross sections in terms of current-carrying capacity for a single-phase and a three-phase 120 V system with effective load resistance of 15 Ω.
Correct Answer: phase current, the line current, and the load current are all equal in each phase
8. A three-phase generator is connected to three 90 Ω load resistors. Each coil generates 120 V ac. A common neutral line exists. How much current flows through the common neutral line?
9. A two-phase generator is connected to two 90 Ω load resistors. Each coil generates 120 V ac. A common neutral line exists. How much current flows through the common neutral line?
10. In a certain Y-Y system, the source phase currents each have a magnitude of 9 A. The magnitude of each load current for a balanced load condition is