The Electrical Grid

Learning Objectives

Describe the electrical grid as a network for delivering electricity.

Identify the three main stages of the grid: generation, transmission, and distribution.

Explain the function of a transformer.

Understand why electricity is transmitted at very high voltages and distributed at lower voltages.

From Power Plant to Your Home

When you flip a switch, a light instantly turns on. But have you ever thought about the long journey that electricity took to get to your house? That journey happens on the electrical grid.

The electrical grid is the vast, interconnected network that generates, transports, and delivers electricity from power plants to consumers. It is one of the most complex machines ever built. The grid can be broken down into three main parts.

1. Generation

This is where the electricity is made. It happens at a power plant. As we learned in a previous lesson, most power plants use an energy source (like coal, natural gas, hydro, or wind) to spin a turbine, which in turn spins a generator to produce electricity.

2. Transmission

Power plants are often located far away from the cities where most people live. The next step is to transport the electricity over long distances. This is done using high-voltage transmission lines. These are the huge metal towers you see carrying thick wires across the countryside.

Why High Voltage? When electricity travels through a wire, some energy is always lost as heat due to the wire's resistance. This power loss is much lower when the current is low. To send a lot of power with a low current, you must use a very high voltage. So, electricity is transmitted at extremely high voltages (hundreds of thousands of volts) to be more efficient.

Transformers: To change the voltage, power companies use a device called a transformer. A step-up transformer at the power plant increases the voltage for transmission.

3. Distribution

Once the electricity reaches a town or city, the high voltage is too dangerous to be used in homes and businesses. The voltage must be lowered.

The transmission lines go to a substation, where a step-down transformer lowers the voltage.

From the substation, smaller power lines, called distribution lines, carry the electricity along streets (either on utility poles or underground).

Right before it gets to your house, another, smaller step-down transformer (often a gray can on a utility pole or a green box on the ground) lowers the voltage one last time to the safe, usable level for your outlets (e.g., 120 volts in the US).

From generation to transmission to distribution, the electrical grid works as a coordinated system to provide the reliable power we depend on every day.

Key Terms

**Electrical Grid: An interconnected network for delivering electricity from producers to consumers.
**Generation: The process of producing electrical energy at a power plant.
**Transmission: The bulk movement of electrical energy from a generating site, such as a power plant, to an electrical substation.
**Distribution: The final stage in the delivery of electric power
**Transformer: A device that increases or decreases the voltage of an alternating current.
**Voltage: The 'pressure' from an electrical circuit's power source that pushes charged electrons (current) through a conducting loop.
**Substation: A part of an electrical generation, transmission, and distribution system where voltage is transformed from high to low or the reverse.