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Old 04-10-2013, 07:41 PM   #15
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This statement you made is not true.

What I said was "a 240 VAC line is actually two 120 VAC lines, 180 degrees out of phase from one another".

You are using the word "phase" when referring to the point on a time line. That is where the confusion is. Here is a comparison to multiphase as compared to single phase.
It is not the 180 degree swings from the positive side to the negative side of the zero line that create the 240 volts. It is the number of turns of wire in the transformer that determine the voltage or potential difference. There are twice as many turns in the windings between the 2 points that measure 240 volts as compared to the 2 points that create the 120 volts.
The sign wave represents the frequency and peak voltages both negative and positive. The frequency is determined by the design and rotation speed of the Alternator. 50 cycle; 60 cycle; 400 cycle and so on.

http://i1166.photobucket.com/albums/...eSineWaves.jpg
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Old 04-10-2013, 07:50 PM   #16
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Sorry to poke fun. Hate to see you guys arguing, but I have to admit this is a very good and technical thread.

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Old 04-10-2013, 08:21 PM   #17
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Look at it with a dual trace O-scope like I said, and you will understand it. I know it's difficult for an Electrician to understand when you are thinking of three phase.
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Old 04-10-2013, 08:28 PM   #18
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I'm tired of the innuendo that we don't know what you are talking about.
You need to take a refresher course in electrical engineering if you think you are right.
Dual trace scope or not. You don't have a clue about how the 240 and 120 volts are created.
I'm done here.
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Old 04-10-2013, 08:37 PM   #19
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Ok, you want to talk about transformer output....think of a transformer with a 240 VAC secondary. When one end of the output winding is positive, the other end of the secondary winding is negative in the sinusoidal waveform. On the other part of the cycle, the voltages reverse. Do you agree with this basic theory?

Now, with the same transformer output of 240 VAC, ground the center of the transformer secondary output winding. Then if you measure from either end of the secondary output winding to the center tap, you will measure 120 VAC, but the total secondary output is still 240VAC, and the output is still positive on one end when it is negative on the other end.

This, my friends, is exactly how the two 120 VAC legs are 180 degrees out of phase in a 240 VAC circuit.
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Old 04-10-2013, 08:54 PM   #20
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I'll give it ONE MORE TRY.
Reference your scope to one end of the transformer. Then connect the channel 1 lead to the 240 tap on the transformer. Connect the channel 2 lead to the 120 volt tap on the transformer.
When you look at the screen, the only difference you will see is in amplitude. Both in the positive and negative.
There is no 180 degree thing involved.
I know it's hard for a telecommunications person to grasp the concept.
But you are still, way off base in this "electricians" mind.
I have done all I can do to try to explain it in layman s terms. Including pictures.
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Old 04-10-2013, 09:33 PM   #21
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Get your o-scope and check it out. Then you might understand. If not then, go back and read some AC and transformer theory.
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Old 04-10-2013, 09:53 PM   #22
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It's dark outside and i can't see the transformer on my pole, so I grabbed my meter and stuffed one lead into the ground hole of my 50 A RV outlet and the other lead into the flat hole...it read 122 volts. I stuffed it into the other flat hole, it read 124 volts. Then I stuffed each lead into the flat holes and it read 245 volts.

Phases? How cares!

My 220 volt, 3 hole dryer outlet had the exact same result...

IMHO, 50A RV = a goofy pin configuration of a 3 pin 220 V outlet
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Old 04-10-2013, 10:08 PM   #23
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Quote:
Originally Posted by HiHoAgRV View Post
It's dark outside and i can't see the transformer on my pole, so I grabbed my meter and stuffed one lead into the ground hole of my 50 A RV outlet and the other lead into the flat hole...it read 122 volts. I stuffed it into the other flat hole, it read 124 volts. Then I stuffed each lead into the flat holes and it read 245 volts.

Phases? How cares!

My 220 volt, 3 hole dryer outlet had the exact same result...

IMHO, 50A RV = a goofy pin configuration of a 3 pin 220 V outlet
Yep, that's exactly what you are supposed to read with an AC voltmeter.
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Old 04-10-2013, 10:22 PM   #24
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I'm terrible when it comes to drawing with a computer, but I found this schematic online that shows 240 VAC, and shows how one 120 volt polarity at a given time in the sine wave is opposite from the other, reference the neutral, or center tap of the transformer.
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Old 04-11-2013, 12:07 AM   #25
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I just read this thread and I thought SteveH was right even before he posted that last picture. But the picture explains it nicely and it makes perfect sense. That must be why he lives in Common Sense, TX!

The key to seeing both phases if to reference each to ground (center tap). To see 240V, you can't reference the center tap, you have to put your scope across the entire (both ends) of the transformer.
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Old 04-11-2013, 07:55 AM   #26
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In the beginning, I should have never said the word "phase", because I know when used around Electricians it gets the nape of their necks all bristled up. When they hear the word, they immediately think of three phase power, and I understand why because that is one of the things they work with.

I don't know of any residential three phase power systems, but there might be, just don't know of them.

My statement was about the pure phase angle of the sinusoidal waveform of the two 120 volt legs in a 240 VAC system.

And, I would like to apologize to "JourneytoRet" for totally destroying his thread about 30/50 power in an RV park.
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Old 04-11-2013, 12:50 PM   #27
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OK. Here’s how it works.

If you increase the temperature and the electro-magnetic pressure on the Dilithium crystals, you can increase the amount of power generated in the reaction chamber, then channel the energy released by the mutual annihilation into a stream of electro-plasma.

Oops wait, wrong thread, sorry.
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Old 04-11-2013, 01:03 PM   #28
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But don't you need a flux capacitor in the circuit also?
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