Power Systems — Distribution
Three-phase power, transformers, why transmission is high-voltage, feeder voltage drop, and PF penalties.
Between the generator and your outlet sits a machine the size of a continent. Its whole design boils down to a handful of formulas: three-phase bookkeeping, transformer ratios, and an endless war against I²R losses — heat that grows with the square of the current.
- 01 Three-phase power ELI5: the grid uses three sine waves, 120° out of step. The payoff is huge: their combined power is constant (no flicker), the three conductors share return…
- 02 Transformers — the reason AC won ELI5: two coils sharing an iron core. The voltage scales with the turns ratio, the current scales inversely, and the power passes through almost untouched.…
- 03 Why transmission is high-voltage ELI5: line loss is I²R — it scales with the square of current. Push the same power at 20× the voltage and the current drops 20×, so the loss drops 400×. That…
- 04 Feeder voltage drop ELI5: copper isn't free and distance isn't either — a long feeder loses voltage along the way as current pushes through the wire's own resistance.…
- 05 The power-factor penalty ELI5: a poor power factor means the wires carry current that does no work — yet the utility still pays for the I²R heat it causes, so they bill big customers…