Term
Electricity fundamentals
Electrical Terms and Definitions
(Current, Voltage, Resistance, Conductors and insulators; electric power) |
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Definition
nCurrent (I) is the flow of electric charges (electrons, or ions),
nUnit of Current: amps (A);
nVoltage (V) is the potential difference that acts as the driving force to the charge flow,
nWork done by voltage driving a charge equals to voltage times the charge or W=q٠V;
njust like work done by force: W=F٠d,
nUnit: volt (V)
nResistance (R): obstacle that hinders the moving of charges,
Unit: ohm (W)
nConductor – low resistance, current easily flows:
nCopper, aluminum, and silver are good conductors.
nEarth is a conductor, when connected using a wire or pipe, it is said to be grounded.
nHuman body is also a conductor.
nInsulator – high resistance, current does not flow:
Rubber, glass, ceramics are good insulators
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Term
Electricity fundamentals
Units of current, voltage, resistance and power; |
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Definition
Unit of Current: amps (A);
Unit of voltage: volt (V)
Unit of resistance: ohm
Unit of power: watt (W)
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Term
Electricity fundamentals
Ohm’s law and electric power, be able to calculate using Ohm’s law and power; |
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Definition
Ohm's Law: current= voltage/resistance or I=V/R
Electric power= current*volagtage or P=IV |
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Term
Electricity—Generation & Transmission
Difference between AC and DC; Where do we get each type, what produces each type; |
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Definition
nDC: direct current, flow of charge always in one direction, produced by batteries, or DC adapters
nAC: alternating current, charge flow alternates back and forth, called alternating current produced by generators at electric power plants; |
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Term
Electricity—Generation & Transmission
Generator and transformer principle: Faraday’s electromagnetic induction; |
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Definition
Electrical generator is a device that converts mechanical energy (KE) to electrical energy, using electromagnetic induction.
Transforms are devise based on electromagnetic induction, boxes on telephone wires
Faraday's law of induction and the most widespread version of this law states that the induced electromotive force in any closed circuit is equal to the rate of change of the magnetic flux through the circuit. Or mathematically,
- [image],
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Term
Electricity—Generation & Transmission
Applications of Faraday’s electromagnetic induction (examples)
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Definition
nRotor (armature): The rotating part of an alternator, generator, (or motor);
nThe rotor usually is the coils;
nStator: The stationary part of an alternator, generator, the stator is usually the magnets, for large unit, also coils known as electromagnet.
nCommutator and the brushes from which electric current outputs.
- Current clamp
- Electrical generators
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Term
Electricity—Generation & Transmission
Structure of a generator & Structure of a transformer |
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Definition
Electrical generator is a device that converts mechanical energy (KE) to electrical energy, using electromagnetic induction
A transformer consists of two sets of coils known as the primary & secondary coils; winded on a silicon-steel core; |
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Term
Electricity—Generation & Transmission
step up and set down transformers, the transformer equation |
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Definition
nSince we cannot create energy (AMOF, we loose some (<1%) during the voltage change), we cannot change power, so
Ip*Vp=Is*Vs, so
Current 1*Volt 1=Current 2*Volt 2 |
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Term
Electricity—Generation & Transmission;
why do we want high voltage for transmission? |
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Definition
| Higher voltage means lower current for the same power transmitted. Lower current means smaller wires are required. Allowing wires to be bought for longer distances to reach more places. |
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Term
Electricity—Generation & Transmission
Why do we want low voltage for household application? |
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Definition
| So current is high making it have short wires to plug incase of fire, Also less chance of applicances shocking the person |
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Term
House electrical hookups and Electrical Safety
What is the purpose of fuse and circuit breaker? |
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Definition
They are used to quickly shut off electricity if flow is too high
Fuses- thin wire that burns up
Breaker- a switch that flips to off |
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Term
House electrical hookups and Electrical Safety:
How is the 3-prong receptacle wired up and why? |
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Definition
The left slot is white (safe), neutral (0 V)
The right slot is Black (death), Live (hot)
The bottom circle is green (peace), Grounded
They are wired this way so the appaliance does not fail if it short circuits
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Term
House electrical hookups and Electrical Safety:
Electrical Shock (What causes it, how to prevent it) |
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Definition
Electrical Shock is when your body is shocked by electric
the flow of 0.1 Amps can kill you
body resistance to current flow is 100000 ohm to a few Mohms (100000's)
To prevent it wear heavy rubber gloves when working to increase resistance |
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Term
House electrical hookups and Electrical Safety:
Example: What to do when face a downed line, electric fire, basement flood, etc. |
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Definition
with a downed wire, you should stay in the car. if you get out of the car jump with both feet landing on the ground at the same time.
with an electric fire, do not pour water on it, use a fire exguistor
if the basement flood, do not enter unless you are sure no source of electric is touching the water, if unsure call an electrician |
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Term
| House electrical hookups and Electrical Safety: |
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Definition
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Term
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Definition
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Term
Fossil Fuel Electric Plants
Fossil Fuel Electric Plants (percentages for each type of fuel fired plant)
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Definition
nFossil fuel electric plants: ~67%;
nMost of Fossil Fuel Plants are Coal Fired: 37% are coal fired (2012 data, down from 51% in 2008);
nGas fired plants ~30 % and still growing;
nOil fired plants: <1.0 %; |
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Term
Fossil Fuel Electric Plants
Know the major parts of a fossil fueled electric generating station
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Definition
| Inlet, turbine 4, tubine outlet and generator |
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Term
Electrical Demand, how it varies by season and by day; |
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Definition
Highest during day, especially mid-day thru afternoon
Base Load defined as amount always needed (supplied by cheapest source)
Peak load defined as extra amount needed during the day (supplied by source that can easily be turned off and on)
Peaks in Summer and Winter, but most in Summer
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Term
| Approximate cost of electricity |
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Definition
avg residential -10.41
avg commerical- 9.1
avg industrial- 6.08
avg transportation- 9.33
our area- 9.17
(all in cents) |
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