The AC Grid refers to the vast, interconnected infrastructure that transports alternating current electricity from power generation sources to end users—homes, industries, data centers, EV chargers, and more. It is built around the principle of centralized generation and distributed consumption, with AC power enabling economical long-distance transmission.
Unlike isolated microgrids, the national or regional AC grid ensures continuous power availability by pooling resources and balancing supply-demand variations in real-time.
How Does the AC Grid Work?
The AC grid operates through four main stages:
1. Generation
Power plants generate AC electricity using turbines driven by fossil fuels, hydropower, wind, or nuclear energy.
Generators produce 3-phase AC power typically at 11–33kV.
2. Step-Up Transformation
Step-up transformers increase voltage (e.g., to 132kV, 220kV, or 400kV) to reduce transmission losses.
Why? Because higher voltages mean lower currents, which reduces resistive losses (P = I²R).
3. High-Voltage Transmission
AC electricity travels through overhead lines or underground cables across hundreds of kilometers.
Transmission grids are often meshed, allowing redundancy and load sharing.
4. Step-Down & Distribution
Substations reduce voltage levels (e.g., 400kV → 33kV → 11kV).
Final distribution occurs at 240V single-phase or 415V three-phase for end users.