Electrical Energy Transfer

The Power Grid

It involves a lot more than just flipping a switch or plugging something into an outlet! If you have ever “lost “ power, you have been

reminded of how much you rely on electricity! Electricity was first used to illuminate a street

and a business in 1886! It was a few more years before scientists figured out how to distribute it over a distance and safely into homes.

Think about how far people have come in less than 120 years.

Vocabulary

Energy- the ability to make things move or change

Fossil Fuel- a nonrenewable source of energy that formed from the remains of organisms that died millions of years ago

Electrical Energy- the energy of moving electric charges

Electric Current- the rate at which charges pass a given point

Vocabulary

Conductor-a material in which electric charges can move easily

Insulator-a material in which electric charges cannot move easily

Electric Circuit- a closed path through which electricity can flow

Series Circuit- a circuit in which all parts are connected in a single loop; charges must flow through each part of the circuit

Parallel Circuit- a circuit in which loads are connected side by side; charges have more than one path on which they can travel

Voltage- the pressure that causes electrons to flow. Current- The flow of electrons through a conductor (similar to

water through a pipe). Watt (W)- a unit of electrical power. Electrical power measured

in Watts is equal to the voltage times the current. (Kilowatt= (kW)= 1000 Watts)

Joule (J)- A joule is a measurement of electrical energy. 1 joule is equal to 1 watt of power for 1 second of time (watts x time = joules).

Generator-a machine that converts mechanical energy into electrical energy

Transformer-a device that increases or decreases electric voltage

Power Grid- a system of wires, transformers, and other devices that carry electric current from power plants to individual users

Electrical Energy:

Energy is the ability to make things move or change. It comes in many forms including light, sound, heat, mechanical energy, and electricity.

Electrical energy, or electricity, is the energy of moving electric charges.

Electrical Energy:

Electricity can move through objects that are good conductors.

A conductor is a material that electrical energy can flow through easily.

Metals are examples of good conductors because of their properties.

What are the properties of metals?

Electrical Energy:

Non-metals are not good conductors of electricity.

They are good insulators. Insulators are materials that electrical energy does not move through easily.

Electrical Energy:

An electric current is a flow of charges particles through a conductor (like a metal). The current must have a pathway through which it can move (like wires).

The pathway is known as an electric circuit.

Electrical Energy:

Simple circuits are closed loops that current can flow though. They provide a return path for the current.

Simple circuits consist of an energy source, an electrical device (load), a switch, and wires.

Electrical Energy:

Circuits run on electrical energy from a voltage source.

Voltage is the electrical energy available for moving a charge.

Batteries are a common source of electrical energy in wireless devices.

Electrical Energy:

Electrical energy used in most homes comes from a power plant.

The power plant produces electricity from other sources. Fossil fuels Hydroelectric power Nuclear power

Electrical Energy:

Electricity produced in power plants must be transported to homes and businesses through a power grid.

A power grid is a system of wires, transformers and other devices that carry electric current from power plant to individual users.

The grid also changes voltages of the current it carries.

Electrical Energy:

Key components of a power grid include: Power plant

(generator) Overhead wires or

transmission cables Towers Transformers Substations Junction boxes

Electrical Energy:

Generators change mechanical energy into electrical energy.

Substations are small plots of land that contain devices to regulate and continue the flow of electricity.

Transformers increase or decrease the amount of voltage.

Power lines enable the electricity to pass over great distances to reach homes and businesses.

Junction boxes provide a way to redirect the source of electricity to multiple places within a home or business

The power plant!Imagine this is the Jack Watson plant… our extension of Mississippi Power. The majority of power plants (like Jack Watson) use coal as a source of energy. The coal is burned to heat water. The heated water creates steam. The steam turns the turbine which turns the generator which creates the electricity that is sent out of the plant.

The electricity produced at the power plant is 3-phase AC power. This means they are producing 3 different phases of AC power at the same time offset at 120 degrees. It would look like this:

Your home only uses 1 phase. So why do they produce 3 phases? 3 x 120o =360o (a circle). This means that there is always a current at peak performance and never a slump in energy production.

From the power plant, electricity is sent to a “step-up” transformer. Because it takes a lot of energy to send

electricity out to homes and businesses, the power behind it (the volts) have to be “stepped-up” (or increased) so it can make the trip.

A step-up

transformer

After leaving the step-up transformer, the electricity will travel along wires attached to power poles. There are two main types of power poles:

High voltage you see these close to

plants, or anywhere

the electricity

being transmitted

a longer distance.

Low voltageYou typically see these in neighborhoo

ds , along streets or

highways… anywhere

with places reasonably

close together.

We stepped-up the power behind the electricity so it could travel, that power needs to be taken back down before it enters your house. This usually happens at a substation.

At the substation, the power goes from

“transmission” to “distribution”. It is taken down to safe levels and sent in

different directions.

The substation has a “bus”. It may not look anything like the bus you ride on, it does pretty much the same job. It sends the electricity where it needs to go.

Notice all of the wires going in many different directions…. Anyone want some power?

Even though the power behind the electricity has been “stepped-down” by the time it is traveling on the wires down your street, it is still about 7,200 volts. The electricity has to be stepped-down again because your house runs on 120-240 volts.

You may have noticed that every few power poles on your

street have something that looks like this on them. This is another type of transformer

that takes the electricity in the wire down to a safe level

before it enters your home.

Electrical Energy:

Electricity TransmissionScaled down

Electrical Energy:

Electrical Energy: Once again, Electricity generated at

a power plant must travel long distances through a power grid to reach its destination. The current follows a specific flow through the grid.

First, a generator will send the current to a step up transformer. The transformer will increase the voltage of the electricity to carry it through wires to a substation.

Electrical Energy: Once again, A substation houses

groups of transformers which will increase or decrease electric voltage as necessary.

The current will then flow through wires to step down transformers which will alter the voltage of the current before it enters homes and business, traveling through a junction box to the outlet.

Electrical Energy:

In some areas of the country, other forms of energy are utilized to create electricity.

Examples of renewable energy sources that can be used are: Solar energy Wind

energy Hydroelectric energy Hydrothermic energy

Electrical Energy:

If these alternate forms of energy produce enough power to create an abundance of electricity in a particular area, then the “extra” electricity can be added to the existing power grid.

In Mississippi, several businesses help to service the power grid by maintaining and operating the power grid.

Kuhlman Electric Corporation in Crystal Springs is a major supplier of transformers.

Howard Industries, of Laurel and Ellisville, Mississippi also supply equipment for the grid.