Electrical Terms and Theory To accompany the Georgia Agriculture Curriculum Course: AG-AMI Agricultural Mechanics I Unit 3:Electrical Wiring 2010 VGP

The Atom

A Copper Atom Electrons (29 total) Protons (29 total) Valence Ring (Outer Ring) The Basic Structure of an Atom Atoms will have the same number of Electrons in the orbit as there are Protons in the center.

Balanced Atom Equal Number of Protons and Electrons

Unbalanced Atom Number of Protons and Electrons is Unequal

Circuit

Positive Charged AtomNegative Charged Atom Too Few Electrons Too Many Electrons

Materials with Electrons in their outer rings make good conductors 132 Because the Electrons are easily dislodged from their orbit and pushed to the atom next to them. (Electron flow)

Materials which hold their electrons closely are good Insulators Electrons are not easily dislodged from their orbit and pushed to the atom next to them.

Electrons flow from atom to atom

Parallel vs. Series Circuits

Electrical Circuit vs. Water

Amperes “AMP” What is an Ampere or (Amp)? A unit of measure of the rate of flow of electricity. “Currrent” One Amp = 6,280,000,000,000,000,000 (6.28 Quintillion electrons passing a point in one second.) Symbol: A or I

Ammeter

Voltage “Volts” What is a Volt? An Electromotive Force. A unit of measure of electrical pressure The force required to move one amp of electricity through a resistance of one ohm. Symbol: E or V Voltages Available: 120 and 240

Voltmeter

Resistance “Ohm” What is an Ohm? A measure of the resistance of electrons to flow in a material. The resistance to the movement of electrons. Relates to four Factors –Material, Diameter, Length, and Temperature. Symbol: R or O

Ohmmeter

Wattage “Watts” What is a Watt? A unit of measure of electrical power A calculated quantity of electrical energy. W = V x A A kilowatt is 1000 watts. A megawatt is 1,000,000 watts.

Wattmeter

Horsepower HP You can change horsepower to watts rather easily by figuring 1,000 watts for each horsepower of motor rating

Kilowatt-Hour Kwh A kilowatt-hour is the unit of measure by which electric power is marketed. Kilowatts x Hours = Kilowatt-Hours

 DC – direct current  AC- alternating current

Current flows in one direction only. Used in flashlights, cameras, boats, automobiles

Current flows in one direction ½ of the cycle then reverses for the 2 nd ½ of the cycle. Used in most home appliances, t.v., radio, computers.

Figure 1-B-29. (a) DC current always flows in one direction, unchanging, as through this automotive headlight bulb. (b) AC current flows in one direction for one-half cycle, then reverses direction for one-half cycle, completing a cycle. This action occurs 60 times per second. (60 HZ)

Hertz A hertz is an international measure of electrical frequency, with 1 Hz being one cycle per second. Electrical outlets have different frequencies in different countries. For instance, while outlets in the United States, Canada and Aruba have frequencies of 60 Hz, outlets in China and Denmark are 50 Hz.

 Single phase 60- cycles per minute  Three phase 180 cycles per minute

Three Wire Service The Current Alternates Directions 60 Cycles Per Second Supplies 120 and 240 Volts

Four Wire Service The Current Alternates Direction 180 Cycles Per Second. Functions at Higher Voltages

 Our power is generated for us compliments of our natural resources  Renewable and Non-renewable

 Solar Energy  Tidal Energy  Geothermal Energy  Solid Wastes Energy  Water Energy  And Possibly Fast Growing Woods

 Fossil fuels ◦ Coal ◦ Oil ◦ Natural Gas  Non-sustainable Woods  Nuclear (uranium)

 Some type of mechanical generator!

Hydroelectric Generation- Accounts for approximately 11% of the U.S power supply

 Fossil fuels  Nuclear Fission  Geothermal  Solid Waste  Wood There are several sources of steam power:

Coal, Oil, & Natural Gas

Accounts for about 51% of steam power generated electricity Decreasing in quality Increasing in pollutants

Accounts for 2% of electricity generated. Once preferred over coal for ease of handling and for how clean it burned In lesser supply now so is a less desirable source

Accounts for about 15% of electricity generated Quickly becoming the fuel of choice.

 Use of existing technology  Low capital cost  Short license procedures  Ability to add small amounts of distributed generation for growth needs without building huge expensive plants  Efficiency and cost effectiveness  Lower environmental impacts

Splitting uranium atoms produces a great deal of heat energy that is processed into electrical energy in nuclear plants. Non-renewable Source

Utilizes the Earth’s inner heated rocks to heat water that reaches these areas through seismic faults. This water is turned to steam them captured to operate steam-powered generators. Renewable Resource

Uses heat generated from burning solid municipal waste to heat water to operate steam powered generators. Renewable resource

Scrap wood is used to power boilers in some mills, but this is a little used practices, obviously for conservation purposes.

 Wind- used near coastal areas and high ridges  Thermal Conversion- mirrors reflect sunlight to heat water  Photovoltaic Conversion- Solar power converted directly into electricity  Tidal – Waves used to turn turbines for generation  Fuel cells- Products of the space age; use fossil fuels without combustion

 Fusion- Adding an extra oxygen atom to H2O creates heat for steam  Biogas- captured methane from landfills  Chemical- batteries (primary cells and storage cells)- ex. Dry cell, nickel-cadmium, lead acid, and gel

 Power is generated by one of the previously mentioned methods and stored.  It is transported as needed to a step up transformer substation.  It is then carried via transmission lines to a step down transformer substation.  Distribution lines carry it to consumers homes and businesses.

Step-up transformers are used at the power plant to increase the voltage and decrease the amperage. As a Step-up transformers are used at the power plant to increase the voltage and decrease the amperage. As a result, efficiency is increased and smaller transmission wires can be used. y is increased and smaller transmission wires can be used.

Step-up transformers are used at the power plant to increase the voltage and decrease the amperage. As a Before the power can be used, the voltage is stepped down and the amperage is stepped up. y is increased and smaller transmission wires can be used.