Visually understand how AC works

[RichyL]

"Nothing has to flow into the ditch, because that's not the goal of our water in this analogy." LOL:grin:

There can be no unbalanced current flowing if more than one ungrounded conductor is not connected to the neutral.Roger

So a straight 240 with no neutral requires a balanced load,for instance most electric water heaters. I think I understand that part. It goes from L1 through the load to the power source at L2 then turns around and goes back the other way, through the load to L1.


http://cast.csufresno.edu/agedweb/agmech/graphics/ElectricityAg4.gif

In 120 volt It looks as if the power is being pumped out in L1 through the hot wire and sucked back in through the hot wire when the switch is off for the light. when the light is turned on it appears that the hot is pumped out through the receptacle and light and carried by the grounded cond. back to the power source and then sucked back in.



I know I'm missing something or getting confused with this concept somehow, gonna reread some chapters and see if it clicks.

 

[George Stolz]

I think it's probably easier to visualize if you forget the alternating nature of the current for a moment. It is neat, but distracting when you're trying to picture the rest of what's going on.

Usually, when I think about current flow and stuff like that, I picture it as it would be in the instant that current is traveling from L1 to neutral. It's shortsighted, but much much easier to picture in this case. There's few times that the alternating nature of the current is germaine to a concept.

 

[roger]

I agree with George, the AC part of this is not really important in visualizing current flow.

Here are a few illustrations that may help, you can just reverse the arrows back and forth to simulate AC.

Take note of the last two showing 1? unbalanced and balanced MWBC's

Roger

 

[quogueelectric]

think of it as two batteries in series

think of it as two batteries in series

with the midpoint grounded. +1.5 volts +1.5volts . Now try to understand how the voltages and polaritys change as you measure from the midpoint in both directions. always using your black lead as the grounded or midpoint. THEN REVERSE THE DIRECTION OF BOTH BATTERYS . And see how your voltage measurements change. Always measuring from the middle. this si just a snapshot of how ac works. I wish I had time to expllain but I am working 7/12s for a month without a day off. Good night irene.

 

[roger]

If you want to use the battery example see the following links.

Thanks to Ronald Coleman.

http://home.comcast.net/~ronaldrc/wsb/ax.htm

http://home.comcast.net/~ronaldrc/wsb/balanced_circuit.htm



Roger

 

[quogueelectric]

excelent tutorials

excelent tutorials

I always feel these simple drawings make it easy to understand.

 

[RichyL]

Thanks for all your help, I am understanding this concept a lot better now. I reread some chapters in my study guide and reviewed your responses and graphics/diagrams. Eventually it just clicked in my mind. It was as if my brain knew what was happening but refused to accept it as logic :grin: kind of like what happened to me when I was first taught how 3-way switches work, I understood what they were saying to an extent, but it just took a little while to sink in. Such is the learning process (for me anyway) Anyways, thanks again and have a happy and safe holiday season.:smile:

 

[bigsid]

How does all of this compare to 240v systems in Europe? Do they also have a neutral conductor or is this something special because we are based on 120v?

In europe their voltage is 220/380 or 230/400 50hz. U have 220volts between your hot and neutral on this type of system because your windings on...let's say the generator which produce the voltage is in a high wye configuration. Meaning your field windings are in series for each leg of the phase. Remember ur coils are wound for a particular voltage (110 or 120) so if ur 1 and 4 coil lead is 110volts and u connect it to ur 7 and 10 coil lead with 4 and 7 tied together in series u now have 220volts to neutral.

I hope that explained it for u.

 

[stevee]

The thing i'm trying to figure out now is how is a load/current only established on the circuit by an ammeter when you have something plugged in , Is there always 20 amps running through a 20 amp circuit, and the meter is only reading the power used out of that 20 amps? Do I ask too many questions?:grin:

Remember voltage is the "potential" to move electrons. Current is the "movement" of electrons.

Imagine a 120v, 20A circuit supplying power to a 100W lamp controlled by a standard single pole switch.

When the switch is open, the lamp is off. The circuit is open (not complete) so no current flows. Therefore you will not read any current on your amprobe.

When the switch is closed, the lamp is on. The circuit is now complete and current flows. Now you will read current on your amprobe.