ENERGY INDUSTRY FUNDAMENTALS: MODULE 1, UNIT A --The Evolution of the Power Industry and Its Regulatory Structure.

ENERGY INDUSTRY FUNDAMENTALS: MODULE 1, UNIT A --The Evolution of the Power Industry and Its Regulatory Structure

THE SCIENCE BEHIND DIRECT CURRENT & ALTERNATING CURRENT

ENERGY INDUSTRY FUNDAMENTALS: MODULE 1, UNIT A --The Evolution of the Power Industry and Its Regulatory Structure

Static Electricity

Static electricity = an imbalance of positively and negatively charged atoms. Electrons then jump from atom to atom, releasing energy.

Examples of static electricity Lightning Shocks from scuffing your feet across the

carpet on a dry day and then touching a metal surface such as a doorknob

ENERGY INDUSTRY FUNDAMENTALS: MODULE 1, UNIT A --The Evolution of the Power Industry and Its Regulatory Structure

Current Electricity

Current = a flow of electrons along a pathway

Direct current (DC) means that electrons flow in one direction. Batteries provide DC.

Batteries consist of two or more cells filled with chemicals. As the chemicals react, electrons are removed, leaving behind positively charged ions. The separation between the electrons and the ions creates voltage.

ENERGY INDUSTRY FUNDAMENTALS: MODULE 1, UNIT A --The Evolution of the Power Industry and Its Regulatory Structure

Batteries

The voltage produced depends on the chemicals used. A “D” cell flashlight battery uses an alkaline reaction. A car battery uses a lead-acid reaction.

The voltage of a cell drops over time as the chemical reaction slows down and the battery dies.

ENERGY INDUSTRY FUNDAMENTALS: MODULE 1, UNIT A --The Evolution of the Power Industry and Its Regulatory Structure

Batteries

ENERGY INDUSTRY FUNDAMENTALS: MODULE 1, UNIT A --The Evolution of the Power Industry and Its Regulatory Structure

Vocabulary

1 Coulomb = 6.25 x 1018 electrons; symbol is C

1 Ampere of current = the movement of1 Coulomb of electrons past one point, in one second; symbol is A

Load: device or customer that receives power from the electric system. Load should not be confused with demand, which is the measure of power that a load requires

ENERGY INDUSTRY FUNDAMENTALS: MODULE 1, UNIT A --The Evolution of the Power Industry and Its Regulatory Structure

Voltage

Voltage is the “push” behind the movement of electrons (current flow)

Unit is the Volt Symbols

DC Voltage Source

AC Voltage Source

ENERGY INDUSTRY FUNDAMENTALS: MODULE 1, UNIT A --The Evolution of the Power Industry and Its Regulatory Structure

Resistors

Resistance is the opposition to current flow

Unit is Ohm (Ω) resistor : A component used

to limit current flow in a circuit or to provide a voltage drop

Symbol : R

ENERGY INDUSTRY FUNDAMENTALS: MODULE 1, UNIT A --The Evolution of the Power Industry and Its Regulatory Structure

Circuits A simple DC Circuit consists of a source,

a load, control and conductors connecting the three parts.

ENERGY INDUSTRY FUNDAMENTALS: MODULE 1, UNIT A --The Evolution of the Power Industry and Its Regulatory Structure

Series DC Circuit A series circuit has a single path for

current to flow. (When the switch is open, the circuit is incomplete and the electrons cannot flow.)

ENERGY INDUSTRY FUNDAMENTALS: MODULE 1, UNIT A --The Evolution of the Power Industry and Its Regulatory Structure

Parallel DC Circuit A Parallel circuit has multiple paths for

current to flow.

ENERGY INDUSTRY FUNDAMENTALS: MODULE 1, UNIT A --The Evolution of the Power Industry and Its Regulatory Structure

Vocabulary Capacitor: a device with the ability to store electric

charge (Ex: condenser in a car) and release it; used in electronic circuits for blocking DC while allowing AC to pass

Transformer: transfers electricity from one circuit to another with an increase or decrease in voltage

Inductor: a coil of wire that can store energy in its magnetic field and resists any change in the amount of current flowing through it; when the current flowing through an inductor changes, it will create an opposing or reverse voltage

ENERGY INDUSTRY FUNDAMENTALS: MODULE 1, UNIT A --The Evolution of the Power Industry and Its Regulatory Structure

Current Electricity Alternating current (AC) means that electrons flow in

two directions. Power plants provide AC. AC current is generated when a conductor—often a

coil of wire—is rotated in a magnetic field. The magnetic field has polarity (north and south

poles). As the coil rotates between the opposing poles, the change in polarity causes a change in direction of the current flow.

The directional change happens at regular intervals. In the U.S., 60 full 360º rotations through the field (cycles) happen every second.

ENERGY INDUSTRY FUNDAMENTALS: MODULE 1, UNIT A --The Evolution of the Power Industry and Its Regulatory Structure

AC Circuit

ENERGY INDUSTRY FUNDAMENTALS: MODULE 1, UNIT A --The Evolution of the Power Industry and Its Regulatory Structure

The War of Currents: General Electric (DC) vs. Westinghouse (AC) Thomas Edison’s power plants provided DC

to customers but could only send it about 1 mile before it lost power. Edison hired Nikola Tesla to find a solution and Tesla delivered, but then Edison allegedly refused to pay him.

Tesla quit and investors helped him establish a competing industrial laboratory where he manufactured the prototype for today’s AC generation and transmission system.

ENERGY INDUSTRY FUNDAMENTALS: MODULE 1, UNIT A --The Evolution of the Power Industry and Its Regulatory Structure

AC electricity is more efficient and more cost effective than DC DC was difficult to convert from higher to lower

voltages and required separate transmission lines for different voltages; AC could be “stepped down” easily through the use of transformers

Separate transmission lines meant great cost and more danger to the public from overhead lines

DC required power plants to be located close to the end user (electric load); AC could transmit high voltage over long distances requiring fewer plants

AC motors are simpler in design than DC motors

ENERGY INDUSTRY FUNDAMENTALS: MODULE 1, UNIT A --The Evolution of the Power Industry and Its Regulatory Structure

An AC power system benefits from: Economies of scale in generation, when

cost of production falls because output has increased

Load diversity, when the peak demands of a variety of electric customers occur at different times

ENERGY INDUSTRY FUNDAMENTALS: MODULE 1, UNIT A --The Evolution of the Power Industry and Its Regulatory Structure

For More About… Batteries and power systems

http://www.eng.cam.ac.uk/DesignOffice/mdp/electric_web/DC/DC_11.html

Electrical components and systemshttp://science.howstuffworks.com/electricity-channel.htm

Inventor Nikola Teslahttp://www.pbs.org/tesla/