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Anonymous Poster

AC power

08/24/2008 3:09 PM

I realize this is such a basic question and I feel stupid for asking it, but I am unable to grasp just how AC generated power works. What exactly does 60 Hz (or 50 Hz) mean? Do generators "pulse" the current at that rate, or does the current actually return to the source at "negative" voltage as indicated on the sine wave graph? If the latter is the case, what causes the current to return to the source? Sorry for the multiple questions.

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#1

Re: AC power

08/24/2008 3:31 PM

You probably need more of an education than you can get here. Search the term "AC Power Basics" including the quotation marks and you should get what you need.


Quick answer though is that yes, the current is changing direction twice in each cycle. The number of cycles it goes through in each second is called Cycles-Per-Second, or CPS. But years and years ago, CPS was given a universal SI Unit term in honor of Heinrich Hertz, a physicist who studies electromagnetic waves. Herts is abbreviated Hz, so 60Hz or 50Hz describes the alternating rate of AC, which of course means "Alternating Current". What makes current flow in a circuit is what is a little too complex for a site like this, although most likely someone will try to type all that in.

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#2

Re: AC power

08/24/2008 3:45 PM

Just a few basic principles used.

If a conductor is passed through a magnetic field a current will be developed.

The direction of movement determine the direction of the flow.

if you now rotate a coil in the magnetic field the direction of the flow will alternate depending on the side of the coil on the particular side.

If you rotate the coil at 3600 rpm the frequency will be 3600/60 = 60 Hz , at 3000 rpm one would get 50 Hz.

This is not the complete story but will give some indication.

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#3

Re: AC power

08/25/2008 3:14 AM

Yes the voltage actually goes through positive and negetive cycles 50/60 times a second,you need to have some basic knowledge of AC theory to understand it can get very confusing if you do not have the basic concept .

the best way is to follow the anology of water flow,

the Volts is equvalent to the force of water flow in the pipe.

the quantity of water flow per sec is equivalent to the qulomb

the amount of water flowing can be equivalent to current flow

The total amount of water flowed to a container in one hour can be equivalent to KWH or one unit of electricity

i hope that will give you some idea of the basic terms in electricity and based on those you will be guided to understand the concepts

Browse through the internate and there is plenty of info. available .

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#4
In reply to #3

Re: AC power

08/25/2008 4:02 AM

The water analogy is better for Dc...I've never seen a water wheel using an alternating flow

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#5
In reply to #4

Re: AC power

08/25/2008 8:58 AM

The "anology" was what was important. I take it by your response that you are what we would call a senior citizen aka an old fart that knows everything

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#6
In reply to #5

Re: AC power

08/25/2008 9:05 AM

Maybe you don't understand the purpose of an 'analogy'...?
It is supposed to be helpful to the process of understanding.

If you want to find out who I am, what I know and what I can do... click on my user name read my profile, check out the links to the stuff I've done ...

Then if you think you are up to the task come back and have a meaningful discussion.

Del

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#7
In reply to #6

Re: AC power

08/25/2008 10:37 AM

If it makes you feel any better, I for one, will forever be indebted to you for The Mighty Boosh........as a source for the best in information and inspiration.

Any apprentice of mine who doesn't get it will be relegated to sweeping the floor ad infinitum until they either sweep themselves out of the box or think their way out.

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#8
In reply to #7

Re: AC power

08/25/2008 11:20 AM

Oh yes...it does make me feel better...
Cheers
Del

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#13
In reply to #8

Re: AC power

08/25/2008 3:52 PM

I second that e-moticon.

I understand where he was coming from, but the OP may be confused by alternating water flow.

What would be a good analogy to understand AC?

All I can think of is ping pong balls flying back and forth, but that would only show frequency. Maybe bigger balls ? Closer paddles?????

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#9
In reply to #3

Re: AC power

08/25/2008 12:39 PM

I suppose my questions were a bit confusing. I believe do possess a basic understanding of AC power. My question relates to the actual method of transmission. In AC, the direction of the current reverses, or alternates, 60 times per second. My question relates to the return flow of the current, or the negative peak voltage indicated on the sine wave graph below:

My assumption is that the negative V peak represents the return path of one cycle. My question is: what causes the current to return to the original power source in an AC cycle and why does it create a negative voltage?

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#10
In reply to #9

Re: AC power

08/25/2008 12:49 PM

The voltage alternates 'cos that's how the generator works...it produces a sinusoidal voltage as it rotates...someone has already described how.

Once you generate a sinusoidal voltage the current flow will follow... flowing from positive to negative (conventional current ..not electron flow)

To imagine it simplistically...if you take a dc circuit with a battery and bulb and repeatedly swap the battery connection the current will reverse every time you swap the terminals.

So to answer the question..what causes the current to return to the original power source in an AC cycle?

The answer is ...the voltage.

You seem to be under the impression that the current is causing the voltage...NO ...the voltage causes the current to flow.

(But you may wish to ignore this post as I'm sust an old fart who thinks he knows everything.)

Del

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#11
In reply to #10

Re: AC power

08/25/2008 1:45 PM

Age aside, your comments are valuable. Ignore the ego driven rantings of youth. :)

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#12
In reply to #11

Re: AC power

08/25/2008 2:03 PM

Cheers...
Del (we all need a good ego driven rant now and again)

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#14
In reply to #12

Re: AC power

08/25/2008 4:01 PM

If the voltage returns back to the electric company, does that mean were paying for the same electricity over and over again??

I've heard rumors that no new electricity has been created since the Late 20th century. But we have no way of proving this.

I think the govornment is behind all this. Just like all those carpet manufacturers putting electrons into carpets to create static electricity.

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#15

Re: AC power

08/26/2008 6:12 PM

As I see it the electricity flows the other way in that cycle because the coil is positioned in the opposite direction to the position when it was giving a positive flow. (that is in a fixed magnetic field)

I would say it is analog (or opposite) to a transformer by changing the magnetic direction of the secondary winding by flipping it around mechanically.

As a child we made "alternators" using a permanent U shaped magnet, a coil around a core on a spindle with a crank handle.

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#16

Re: AC power

08/28/2008 6:59 AM

Nikola Tesla was curious man and a lot of people today has big problem with his ideas and work . Dear guest ,don't afraid find some good book or spend more time at school !!
Good luck !

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Anonymous Poster
#17

Re: AC power

09/02/2008 7:57 AM

Hello,

AC is alternating current. This nothing but flow of electrons in sinsuodal fashion with a frequency of 50/60 cycles per second. That mean a sinusoidal wave of 50 /60 times per second will be there. In otherwards the current starts from zero reaches postive maximum, then zero, negative maximum and then zero.

Phase is the direction of power flow with neutral the return path.

Hope you are clear.

Regards,

N.Suresh

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