I've been scratching my head over something. I have a scenario (theoretical) where you can either use 2 wires @ 230V or 3 wires @ 200V 3-ph. The size of the wires is limited by voltage drop, which is the same percentage wise for both cases. According to textbooks and common knowledge, 3-phase is more efficient than just using two wires. But I fail to arrive at this result in this case.
If I put 1A load the 3-ph case I need 1.73/1.15 = 1.5A single phase to get the same power. This means I have to increase the cross sectional area of the conductors by 50% compared to the 3-phase case. But I only need 2 wires instead of 3 and am back at the same amount of copper.
Is there something wrong with my calculations? Wouldn't be the first time...
You've found an identity (In the mathematical sense.) For the same potential to neutral and the same 'aggregate current', you get the same VA delivered to the load, no matter 1 phase or 3 phase or 17 phases
#128851 - 02/23/0411:25 AMRe: Is there something wrong with my calculation?