The following is how electricity works as I understand it. I know that the electrical engineer types out there are gonna have a good laugh at this, but I have never seen this scenario layed out so the layman can understand it. Feel free to make any corrections, I am sure you won’t hold back.
Electrons are ” created ” at a power plant when a magnetic core is spun inside a copper wire housing. An alternating current is created by the spinning magnet, as the positive and negative ends of the magnet pass the same point.
The electrons move back and forth approximately 60 times per second, hence the designation of “120 -volts or hertz or whatever. The electron takes one step forward and then one step back, this happens 60 times per second.
The mechanical force to spin the magnetic core comes from a water turbine in dam , an internal combustion engine(oil), steam(coal), wind, etc.
This is different than DC, direct current, which is what comes from electricity stored in a battery. The spinning magnet causes the AC current, whereas with DC, the stored electricty just flows out like water in a resevoir.
Wires leading from the copper coil lead to our homes and work places. As the magnet spins, and electrons are being created, they are “pushed” along the wires as more electrons are added to the system.
Do power plants have large batteries where they store up electricty that is introduced into the grid whenever demand spikes? If so how can it be AC current, and not DC current. If not, how does a power plant deal with varying demands in electricity throughout the day?
We could tag 1 electron, let’s call it X. X is constantly taking one step back, and one step forward. However X is on a moving sidewalk, like in airports. The rate of forward movement is not constant. When you flip on an incandescent light, X moves forward. It enters your house through the one of the two hot lines in your main panel. It then goes through a 15 amp breaker, and follows the hot line to the light.
This is all happening at the speed of light, when X hits the filament in the bulb forward movement slows down. The filament is a resistor, it is hard for the electrons to move through it, and because of this heat is created.
We then lose some of the electrons as heat is created. Electrons are converted to heat as they are forced through the filament. Less electrons end up down stream of the filament. The remaining electrons follow the neutral wire back to the neutral bus bar in the panel, which then goes back to the power station. I assume they just recycle it and send it back out.
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All theories about electricity break down at some point; they're useful only to the extent that they allow you to predict the behavior of electricity.
For all practical purposes, you ought to be able to think of electricity as a fluid - like hydraulic fluid - flowing in a closed loop ... from the pump (generator) through the hoses (wires) to the load (appliance) and back to the pump (generator).
Generally, the more you vary from this model, the more likely you are to have problems.
Another simple model is the "smoke" model: there's smoke in the wires, and all is well as long as the smoke doesn't get out! :D
And the opposite is also applicable.Recently we were studying changes to a chilled water system in a transmitter application. The RF and electrical engineers were arguing over ways to plumb to solve some issues.I kept saying "draw the circuit" to see if it works. I finally got through to the PHD, and he saw most of the proposals would not work. Volts is pressure and current is gpm. Kirchoff seems to apply in fluids just fine.Frank DuVal
Not totally correct but as long as they keep stealing the d**m wire for the copper, nothing is going to work.
No, the electrons pile up in the light bulb until it burns out. The light bulb people don't want you to know this.
And I always thought the lightbulbs sucked up the dark. For instance batteries in flashlights store Dark, when freshly charged are a vacuum of Dark, or absence of Dark. Turn on the switch and they start sucking up Dark therfore creating Light.
No, dark is produced by Dark Emitting Diodes (DEDs), a little-known product that's produced on the same manufacturing lines as LEDs. No one has ever succeeded in optimizing the production of DEDs (for some reason they always lose their jobs when they get close), but curiously, the percent of DEDs produced on one of these manufacturing lines, when added to the percent of LEDs, always totals to 100%.
If your view never changes you're following the wrong leader
well, of course, you don't want to upset the Dark/Light ####. Violating The Continuum would allow those on the Dark Side to Travel to the Light Side & vice verse. Member trading of the two sides has always been claimed to be the beginning of cats & dogs living together.
So, in your opinion, how was Dark produced prior to the advent of DEDs?
Actually, there wasn't any dark prior to DEDs. They've been making DEDs for centuries, but for some reason the rate of LED production has increased in recent years, probably a result of global warming.
If your view never changes you're following the wrong leader
I think I'm starting to see the light.
I wonder what I wrote that warranted the 4 #'s from prospero? I thought I wrote Dark/Light Continuum but it's allowed later. Go figure.
I wonder what I wrote that warranted the 4 #'s from prospero? I thought I wrote Dark/Light Continuum
If you think about it for 2 seconds you'll figure it out.
Too late to think for 2 secs. I kinda have an idea but it passed spell checker.
Actually you can get dark out of incandenscent lights. You feed the imaginary componet of the current.Saw it in Popular Electronics..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
To this day I remember that issue of PE, sometime in the 50's, I have that issue and many others stored in boxes for now. Yup kinda got sucked into that one till I realized the issue was April ;-)Nobody gets in to see the wizard...not nobody...not no how!
Dark-Emitting Diodes..........oh man that one cracks me up!
I'll go to sleep tonight thinking about all those happy little electrons jiggling back and forth on a walkway that's moving the speed of light.
Very funny........Ed
I concurr that the speed of dark is faster than that of light too.
Like when you switch on the lights in a dark room, the dark gets out faster than the light can get in, other wise the ripples of LARK would XRAY you and ruin your retinas for ever and ever.Spheramid Enterprises Architectural Woodworks
"If you want something you've never had, do something you've never done"
I'm with ya! Light bulbs suck the dark out of the room, send the "dark" over wires to the large power plants which compress the "dark" into small pieces which are taken away by he trainload and then buried in deep "dark" caves.
(I've seen the trains carying the small pieces of dark away)
yeah, once you realize that 'New' batteries are actually just empty and waiting to be filled with dark you start to see the world in a different light. For those having a hard time following along think of a battery as a dark storage device. Lot's of dark can be stored in the batteries. Clicking the switch on flashslight enables the filament to abosorb the dark. If it were any other way why would they call it a Fill-a-Mint?
It must make a lot of cold when they cram all the dark together to make the lumpy dark that you see in the train cars. I say a lot of cold because there certainly seems to be an imbalance of cold/hot at the power plants.
I'm with ya! Light bulbs suck the dark out of the room, send the "dark" over wires to the large power plants which compress the "dark" into small pieces which are taken away by he trainload and then buried in deep "dark" caves.
(I've seen the trains carying the small pieces of dark away)
Correct. And with all the Dark Matter in the universe (what is it, 90% or something like that?) we'll never run out of work. You can't see it, touch it or feel it (kinda like s*x with my wife) and it's everywhere.
It's us workers in the electrical industry that brought light and hope out of the infamous "dark ages", starting with Ben Franklin inventing lighting.
Ed
Edited 10/21/2007 1:14 pm ET by edlee
"No, the electrons pile up in the light bulb until it burns out. The light bulb people don't want you to know this."This brings to mind a story by humorist James Thurber, who wrote that his elderly aunt never quite understood how electricity worked when they converted her house from gaslight. If a bulb burned out, she would put a cork in the socket "to prevent electricity from leaking out into the room".BruceT
What? Doesn't everybody?
If your view never changes you're following the wrong leader
Power plants have batteries, but they are just used to operate relays, switches, and other control devices.
Demand is supplied by varying the input power to the generator, i.e. more steam or water to the turbine. Keep the rpm constant so the output is always 60 Hz. So if the demand is low, extra steam would cause the rpm to increase, so the controls look at rpm and adjust the amount of steam going to the turbine. This is the simple description. Think cruise control for a generator, but very fast response.
The rate of forward motion for an electron is the same at all times. Basically the speed of light but slowed by the velocity factor of the conductor. More current is more electrons, not faster electrons.
Electrons are not lost in the filament, their energy is converted to heat. No electrons are harmed when they do work. They do return to their source, a complete circuit.
BTW, generators can be made to produce DC, remember when cars had generators instead of alternators?
Frank DuVal
Electrons are not lost in the filament, their energy is converted to heat. No electrons are harmed when they do work. They do return to their source, a complete circuit.
If the world were DC then the image of what is happening to the path and voltage of the electrons would be easy to visualize (water in a pipe model).
But the AC aspect is what confuses that picture. It's harder to get a mental picture of the electrons' motion when they are subject to a voltage wave that is constantly changing, especially in regards the relationship between hot and neutral across a load.
Ed
Edited 10/21/2007 8:49 am ET by edlee
For AC one needs to use their imagination to see the imaginary part of the power in inductive and capacitive circuits. For pure resistive loads, ohms law still works. But yes, with AC the electrons do reverse motion....Maybe clear glass conductors would help with the visualization!Frank DuVal
Glass conductors and red or blue electrons hows-about.
So the electrons reverse direction..........a hot wire carries the electrons across an A-lamp filament, voltage drops 120 and they flow through the neutral at (nominally) 0v.
Direction reverses, and the electrons flow from the neutral, across the filament, and hop up (or down!) 120v to flow back through the hot...........
You catch my drift about the problem with visualizing this action and the hot/neutral relationship?
Edited 10/21/2007 10:43 am ET by edlee
All I know is that I am in the dark!
To Yojimbo2, look at what you stirred up.
BTW, think about a portable generator. They produce electricity that goes nowhere until you supply the demand.
They use some gas just running but when you turn on the power saws, grinders, etc. the load increases and the engine producing has to work harder and sucks more gasoline to produce the demanded electricity. That is the tip of an iceburg on power plants but many are interconnected, and some oscillate and come on line at different times depending upon overall demand in the grid.
Thats my 2c
generating stations do not have big batteries in them.
they simply run the generators at 100% rated capacity 24 hours a day... to meet demand most coal fired plants having two or more generators can choose not to run them all since it is mostly a matter of maintenance more than fuel consumption as most plants are well past their designed life.
Nukes on the other hand can out-produce any other type of generation and just run and run and run at full reactor power until something breaks or it needs to be refueled. but they are facing the same dilemma as other types of plants. old age
a large portion of the nuke fleet was to be de-commissioned in this decade but there are no replacements being built ......they were only supposed to last 30 years and are getting licenses to run another 30 years while using technology and equipment that is antiquated to say the least
and your electrons being pushed idea is a good one, except they are not being "created"
and a single electron will probably move only a few inches through a wire if you leave the lights on all day
also the power plants generate very large voltages for transmission over long distances, the plant I am working at now cranks out 765,000 volts and 1090 million watts on the line that runs from the shores of Lake Michigan to a substation near Ft, Wayne Indiana, the other small line runs at 345,000 volts and 1050Mw and connects to a nearby Michigan grid
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and a single electron will probably move only a few inches through a wire if you leave the lights on all day
So again the water-in-the-pipe model fails. If the electrons move near the speed of light, then in a 60th of a second one could move 186,000 divided by 60, call it 3,100 miles.
So clearly the electrons are not the force at work here....it's the pressure wave, call it emf, that must be moving through the wires near the speed of light.
yep, according to Mr. Einstein for anything to move at the speed of light it would gain mass which could probably be catastrophic when ever we closed a breaker or cut a hot wire....hoo boy what a messso basically only one electron "falls" out for every one that enters a garden hose 186,000 miles long.
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As one electron gets excited, it gets irate and smacks its neighbour, who gets excited,........
I always hated the water analogy. Most people think of a garden hose, but that is an open system. A closed loop heating system would be better or even a hydraulic system.
Hey that is correct. While the electron movement is slow and limited, the electric and magnetic fields close to the surface of the conductor are what move at almost the speed of light.Nobody gets in to see the wizard...not nobody...not no how!
and your electrons being pushed idea is a good one, except they are not being "created"
As the magnet spins inside the copper coil housing, electrons are not "created". Electrons just exist , they are everywhere. When you rub wool on a balloon, static electricty builds up on the skin of the balloon.
and a single electron will probably move only a few inches through a wire if you leave the lights on all day
Is there something else moving forward other than the electrons, or is the filament in the bulb such a bottleneck that the flow is so slow?
Think of the desk top "toy" with the row of ball. EAch on hanging down from a support on a string. And all of the ball touch each other.Take the left ball and let it swing into the group of balls. When it hits the ball on the far right will bounce. The balls in the middle will move very little.This is similar to the way that electricity causes electron movments..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
You know what annoys me about electricity?Those electrons travel at the speed of light. That means the electrons are going to the power plant and back out to our homes over and over again many times per hour. So the power companies are selling us the same electrons over and over. How do they get away with that?
Kinda like politicians.
If your view never changes you're following the wrong leader
cuz they can !!!.
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you have discovered the POCOs secret.the generator is just a huge hairball inside a glass thermos :)and the lamp glows because the wire is all ziggy zaggy which causes the electrons to slow down in the curves or else they end up as the dark spot on the glass
those are the stupid atomsto get things really moving at near the speed of light you need a particle accelerator like the APS at Argonne Labs...where they try to discover new wonder fabrics and drugs
http://www.aps.anl.gov/About/APS_Overview/index.html
( I worked in the Linac and storage ring )or the Tevatron out at Fermilab......the folks out there seem to just jog all day and run up one HUGE electric bill looking for little things with names like strange and beauty and shooting neutrinos at Minnesota
http://en.wikipedia.org/wiki/Fermilab
( I hung out at DZero for a little while ):).
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OK I found a picture the giant hairball machine. as you can see there are three steam turbines needed to turn the hairball at the right of the picturethis is obviously NOT a coal burning plant.. although the turbine floor in those is relatively clean, just not spotless like this nuke.
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1090 million watts on the line that runs from the shores of Lake Michigan to a substation near Ft, Wayne Indiana, the other small line runs at 345,000 volts and 1050Mw and connects to a nearby Michigan grid
That's almost 1.21 Gigawatts! You could almost power a flux capacitor!Pete Duffy, Handyman
that is correct pete...a flux capacitor would be the answer to our problem of huge hairballs and having a circuit travel 150 miles to its destination.
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yojimbo2
When in the navy I was taught about hole flow theory . electrons don't "flow" there is an absence of electrons which cause the energy of moving electrons to flow.
"If not, how does a power plant deal with varying demands in electricity throughout the day?"
You're about to get an electrical theory answer from a finance guy who works for a power company, so prepare yourself. I only took one year of "pre-business," otherwise known as engineering in college, but am confident I know enough to be dangerous.
On any given interconnected power grid, certain generation units provide what is known as "regulation." These units are paid to "cylce" up and down to match the load on the system, since at all times generation and load must be equal. The vast majority of power plants run "baseload," which means they go to a set point and stay there, but certain units vary their output to match the varying load. This is tougher on on the equipment and the plants are paid accordingly for this service.
Your question about how does a power plant exactly match the number of electrons used versus those consumes has to do with frequency. In the US, electrical devices are designed to run on 60 Hz, or 60 cycles per second AC. However, this requirement does come with a bit of flexibilty. Typically devices can run from, say, 59 to 61 Hz without much more distortion than the barely noticeable dimming of your lights. So as power plants "regulate" their output by putting more or less electons on the grid, the slack is taken up by the ability of the devices to handle variable frequency, however slight. Power company engineers are remarkable adept at predicting load based mainly on weather, but occassionally problem occur, most notably the forced outage of a big unit like a nuke. In this case, other units are broughht online, but in the meantime frequency drops until the system can stabilize itself.
Engineers made more money out of college, but finance is the way to go.
very nice explanation,I have asked control room operators how they do it and they simply shrug their shoulders and say "magic"....... as you say it is mostly calculated, along with some really good guessing and historical data.it is also a game with the NRC posted outputs of the nukes on any given day since they only need to run for ONE minute on any day to state they were online and trip free Cook had a trip a few weeks back due to some maintenance activities but were able to reclose the breaker before midnight. so they were still "trip free".
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"Typically devices can run from, say, 59 to 61 Hz without much more distortion than the barely noticeable dimming of your lights. So as power plants "regulate" their output by putting more or less electons on the grid, the slack is taken up by the ability of the devices to handle variable frequency, however slight. "Actually frequency is very, very tightly controlled. That is all of them that are on the grid, which is all public utilies.I know of on untility that back in the 60's dropped frequencies after their tielines when down so that they could keep supporting a small city that had been getting power from an other utility.To get back to normal operation TVA had to drop all of their tieline and drop frequency to match LG&E and restore the tieline and bring them all backup.It was decided that they would not do that again.Years ago part of Purdue was on public power and part was generated on campus. In the power how they had clocks on both system. Saturday night there would slow down or speed up the local power to get the clocks back in sync..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Like someone else said, electrons are neither created nor destroyed. Actually, the conductors are made up of them (they come pre-packaged as part of atoms.) So if the electrons got used up, then the wires would eventually shrink up and disappear. Or only protons and neutrons would be left, but they are pretty small compared to electrons.
Anyway, in a nutshell and simply:
Current is electrons MOVING through a closed path. An ampere is a certain # of electrons moving past any given point (in a closed loop) each second. More electrons moving past that point each second = more amps.
Voltage is what pushes or pulls those electrons through a closed loop. In the US, the push/pull occurs every 1/60th of a second. 60Hz. Think of pedaling a bicycle at 60 rev/sec. Your feet are always 180° apart. Sometimes one is at top dead center (TDC) and the other is at Bottom (BDC). Sometimes they are both at the horizontal position. But always 180° apart. Think of the horizontal position as 0 volts, TDC and BDC as 120 V each away from horizontal. When one pedal is at the top, the other is at the bottom, and you have 240 V from one pedal to the other, and 120V from EITHER pedal to the horizontal.
Resistance resists the flow of electrons, and dissipates that energy by giving off heat and/or light. Since it must be a closed loop (circuit) to have current, what goes into any point on the path must come out of that same point on the path. No electrons get used up, convert, disappear, leak out, or otherwise. They are still there. All of them. The ENERGY is dissipated, not the electrons.
Hope the was somewhat helpful. When I think of electricity in a house, I boil it down as simply as I can. I don't really care that the electrons move back and forth every 1/60th of a second. I just think of one electron ("be the electron") and the path it wants to take. It goes from the panel supply, through the breaker, through the conductors, through the device, and back to the panel through the neutral. (yeah, I know, 240V circuits work differently, but I'm trying to keep it simple here)
Be the electron.
Pete Duffy, Handyman