Electrical Principles, Terminology, and Safety

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Electrical Principles, Terminology, and Safety

• AgSc 221 Intro to Ag Mech IMS 8602-A

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The Use of Electricity

• It is so common that most people assume that it
  will always be available on demand. The use of
  electricity has grown to the extent that an
  increasing portion of the home budget is used in
  paying for it.

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Definition of Electricty

• Defined in two ways
• Layman terms
• A form of energy that can be converted to light,
  heat, sound, and motion.
• Electrical engineers
• The flow of electrons from one atom to another.

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Definition of Electric Circuit

• The flow of electrons. The amount of energy
  produced depends on the number of electrons in
  motion. What is an electron?

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Basic Atom Terms

• Nucleus?
• Proton?
• Neutron?
• Valence?
• Copper is a great conductor!

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How Electricity is Made

• Produced from generators that are run by water,
  steam, or other energy forms.
• Hydroelectric generation is power made by water.

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In Texas

• Less than 5 is produced hyrdoelectrically
• More than 85 of energy is made from steam power.
• Heat used to make steam is supplied from fossil
  fuels, nuclear fission, biomass, wood, wind, and
  geothermal.

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Process
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Electricity Distribution

• Through wire lines called transmission or
  distribution lines.
• Through lines at 69,000 to 750,000 volts b/c of
  step-up transformer.

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Electricity Distribution

• Voltage drops when arriving at use location down
  to 7,200 to 14,000 by a step-down transformer.
• Transformers at residence reduces voltage again
  to 120 or 240 volts.

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Step-up or down transformer
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Definition of Transformers

• Devices used to increase or decrease the amount
  of voltage.

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Tranformer

• A basic transformer consists or two coils, a
  primary coil and a secondary coil wrapped around
  an iron core.

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Transformer

• Electricity is increased through induction, the
  build-up or and breakdown of a magnetic field in
  a coil.

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Definition of Circuit

• A Circuit is the path through which an electrical
  current flows.
• A current is the movement of electrons through an
  electrical conductor.

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Open and Closed Circuit
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Load

• Load is any device that converts electrical
  energy back into another form of useable energy.
• What are some examples of loads?
• Light bulbs, computer, radio, etc.

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Electrical Circuit

• Made up of three wires
• Hot wire
• Neutral wire
• Ground wire

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Hot Wire

• A conductor that carries electrical pressure to
  the load.. They will show voltage on a
  voltmeter. (Color code usually black or red)

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Neutral Wire

• A conductor that carries current from the load
  back to the source. They are zero voltage.
  (Color Code usually white)

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Ground Wire

• The conducting wire that transmits the electrical
  current to the earth to minimize the danger from
  electrical shock. (Color Code can be green or
  bare wire)

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Wires

• Usually made of copper because it is a goooooood
  conductor. A conductor is any material that
  allows electrons to move readily offering low
  resistance.
• Best
• Gold, silver, copper, aluminum, and bronze.

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Insulator

• A material that will NOT conduct electricity
  because it will not release its own electrons.
• Examples
• Glass, paraffin, porcelain, rubber, silk, cotton,
  dry wood, and most plastics.

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Terms for Current

• Amperes
• Flow of electricty, abbr. by A or I
• Amperage
• Or amp which is the rate of flow per second

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Terms for Pressure

• Volt
• Unit of measure or electrical pressure, abbr. by
  V or E
• Voltage
• Can be compared to water pressure per square
  inch. Can be present whether machine is in use
  or not.

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Terms for power

• Electric power is measured in watts. (abbreviated
  as W). It may be referred to as wattage.
• 1000 watts a kilowatt (kW)

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Formulas to Know

• Watts Volts x Amperes
• Volts Watts/Amperes
• Amperes Watts/Volts

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For Example

• If a 100-watt light bulb operates at 120 volts,
  it will draw how many amperes of electricity.
• Amperes 100 watts/120 volts
• Amperes .833

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Horsepower

• Most electrical equipment is rated in watts.
• However, electric motors are measured in
  horsepower. (hp)

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Horsepower

• Horsepower the unit of mechanical power equal
  to 746 watts of electrical power

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Resistance

• Is any material that opposes the flow of
  electricity.
• Conductors have low resistances, insulators have
  very high resistance
• The unit of measure of electrical resistance is
  known as an ohm.

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Factors that effect resistance in a conductor

• 1. The material of which the conductor is made.
• 2. The size of the conductor.
• 3. The length of the conductor.

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Types of Circuits

• Two basic types of circuits
• 1. Series
• 2. Parallel

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Series Circuit
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Parallel Circuit
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Types of Current

• Direct Current flow one way
• Car batteries
• Dry cell batteries
• Alternating Current
• Lights
• refrigerators

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Current

• Cycle is the flow of electricity with voltage
  fluctuation.
• Term for cycles per second is hertz (Hz)
• U.S. power suppliers control the power to 60
  hertz.

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Types of Electric Power

• Single Phase
• Most common electric power available to consumers
• Three Phase
• Designed especially for large electrical loads

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Circuit Failures

• Caused by
• 1. Open circuits
• 2. Overloads
• 3. Short circuits
• 4. Ground faults.

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Vocab

• An overload occurs when ever excess current flow
  through a circuit.

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Vocab

• A short circuit occurs when current flows through
  an unintended path.

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Circuit Protection Devices

• 1. Fuses
• 2. Circuit Breakers
• 3. Ground Fault Circuit Interrupters

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Fuses

• Plug
• Cartridge

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Circuit Breakers
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Circuit Breakers
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GFCIs
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GFCIs

• The NEC (National Electrical Code) requires
  GFCIs for all 120V, single-phase, 15 and 20 amp
  receptacles installed outdoors, in bathrooms, and
  in garages for residential buildings.

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Organizations

• National Fire Protection Association (NFPA)
• Underwriters Laboratory (UL)

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The End

• All information was taken from IMS curriculum
  8602-A.