Volts leaking to ground rod

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Bluebinky

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No they are not 180 degrees out of phase they are referenced from a mid point. There is no way they could be 180 degrees out of phase with each other as there is only one winding that has a center tap unless there has been something new invented that will somehow let one winding be 180 degrees away from itself.

What the scope is showing is a vector that is referenced from half way through a 240 bolt winding. As can be clearly seen is that while channel A is positive channel B is negative which means they are in phase not 180 degrees out of phase.
In order to be 180 degrees out of phase then both ends would have the same polarity.

Ever hear the old saying to believe nothing you hear and only half of what you see? Well that applies here until you take a course in vector math.
With all due respect, the signals being shown are 180 degrees out of phase.

Forget about which way the windings go, center tapping, or whatever -- look at the two signals. Vector math? Better hit the books again before trying that one.
 
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Reach4

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It doesn’t matter about my words the fact remains the same about the scope and the 180 degrees out of phase. The laws of physics remain true and there is no way possible that the two ends of a single phase winding to be 180 degrees out of phase with each other.

It doesn’t matter what one tries to prove using the picture of a scope especially if they don’t understand vector math, the fact remains that the two ends of a single phase winding are in phase with each other.
If you cannot agree that this picture of an oscilloscope shows channel A being 180 degrees out of phase with channel B, then your use of words differs from the norm.
tektro6.jpg

It doesn’t matter what someone has read or been told all that matters is the laws of physics which prove the fact that using a scope to look at the sine wave of a center tap winding shows that the winding is in fact in phase with each other
I am confident that we both know how the voltages on the two hot legs on a 120/240 AC breaker box relate to each other and the ground/neutral. There is no argument on the underlying physics.
and there is no way possible that the two 120 volt sine waves are 180 degrees out of phase with each other.
It's a terminology thing. Do you don't seem buy into the normal terminology.

Here is a list of statements. Which is the first in the list that you disagree with?

1. A voltage is measured at one point with respect to another point.

2. Measuring the vector, complex, time-domain or frequency domain voltages on 120 VAC hot lines with respect to the grounded wires is the common way. (sorry about the long drawn out wording, but wanted to avoid ambiguities)

3. That way is reasonable.

4. Two sine waves that have their most positive instantaneous voltage occur at the same time can be said to be in phase.

5. Presuming the same frequency for both and presuming a common reference point, a sine wave observed on one wire that has its most positive instantaneous voltages occur at the same time as the most negative instantaneous voltages occur on a different wire , the voltages would be described as out of phase with each other.

6. The oscilloscope picture shown shows two out of phase (180 degrees out of phase) sine waves.
 
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Bluebinky

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JW, try this thought experiment...

Remove the transformer core and set it on the ground. Then from the tap point follow the winding on one leg to its terminal. Now go back to the tap and follow the other one. If you don't move anything or change your view angle or whatever, you will notice that you were following (something like) a spiral. However, one leg was going clockwise, and the other counter-clockwise. On the other hand, if you went end to end, the direction would not change as you passed the tap.
 

JWelectric

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JW, try this thought experiment...

Remove the transformer core and set it on the ground. Then from the tap point follow the winding on one leg to its terminal. Now go back to the tap and follow the other one. If you don't move anything or change your view angle or whatever, you will notice that you were following (something like) a spiral. However, one leg was going clockwise, and the other counter-clockwise. On the other hand, if you went end to end, the direction would not change as you passed the tap.
Hence my mention of vector math. What you are trying to do is start in the middle of the winding and add 120 to 120 which would be N to A plus N to B. This math will result in the same answer should you add the 120 from A to N and then N to B which will be the manner in which the electrons flow through the winding.

What can’t happen is to have electrons flowing from N to A at the same time that electrons are flowing from N to B. This type of configuration would indeed be two 120 volt windings that are 180 degrees out of phase with each other.

The fact that the electrons are entering at one end of the winding and exiting from the other end of the winding and reversing this process 60 times a second is more than enough to prove that the two 120 volt sine waves are indeed in phase with each other and could not in any way be 180 degrees out of phase with each other.

What is 180 degrees out of phase is the method in which you are viewing the two sine waves, not the sine waves their self.
 

Bluebinky

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Two (sinusoidal) signals which are the same amplitude and phase are in fact the same signal and measuring between them will result in no information (power/voltage/whatever). An analogy would be a battery with two positive terminals.

Lets try something even simpler...

The two terminals of a single 120V leg are 180 degrees out of phase -- no matter how you measure them and no matter what reference you use. Does anyone besides JW disagree?
 
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BobL43

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It doesn’t matter about my words the fact remains the same about the scope and the 180 degrees out of phase. The laws of physics remain true and there is no way possible that the two ends of a single phase winding to be 180 degrees out of phase with each other.

It doesn’t matter what one tries to prove using the picture of a scope especially if they don’t understand vector math, the fact remains that the two ends of a single phase winding are in phase with each other.

It doesn’t matter what someone has read or been told all that matters is the laws of physics which prove the fact that using a scope to look at the sine wave of a center tap winding shows that the winding is in fact in phase with each other and there is no way possible that the two 120 volt sine waves are 180 degrees out of phase with each other.
Even Newton knew the law of physics with the apple thing, but when he discovered figs, he sold a product to Nabisco. As to this sine wave issue, I'm going to remain Neutral. Too much talk; I'm so confused.
 

JWelectric

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Two (sinusoidal) signals which are the same amplitude and phase are in fact the same signal and measuring between them will result in no information (power/voltage/whatever).
Two different signals can have the same sinusoidal and amplitude and originate from two different channels and be different such as in a “SINGLE” phase transformer

An analogy would be a battery with two positive terminals.
the battery you mention is an analogy of two different sources that are in fact 180 degrees out of whack. Take the two cell flashlight and reverse on battery or should I say turn it 180 degrees and this is just what you have, a battery that has the same polarity on both ends.

Lets try something even simpler...The two terminals of a single 120V leg are 180 degrees out of phase -- no matter how you measure them and no matter what reference you use. Does anyone besides JW disagree?
The scope at which you are looking at to see what you assume means to be 180 degrees out of phase is looking from the middle at both ends at the same time.

This is more than enough to prove that while one end is positive the other is negative or the two signals are in phase with each other. If you are going to look at the scope at least try to understand what you are seeing. Channel A is positive then Channel B is negative meaning that there is one 240 volt signal that you are looking at the two halves of at the same time. They are in phase with each other not opposing each other.
 

JWelectric

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Two (sinusoidal) signals which are the same amplitude and phase are in fact the same signal and measuring between them will result in no information (power/voltage/whatever).
Two different signals can have the same sinusoidal and amplitude and originate from two different channels and be different such as in a “SINGLE†phase transformer

An analogy would be a battery with two positive terminals.
the battery you mention is an analogy of two different sources that are in fact 180 degrees out of whack. Take the two cell flashlight and reverse on battery or should I say turn it 180 degrees and this is just what you have, a battery that has the same polarity on both ends.

Lets try something even simpler...The two terminals of a single 120V leg are 180 degrees out of phase -- no matter how you measure them and no matter what reference you use. Does anyone besides JW disagree?
The scope at which you are looking at to see what you assume means to be 180 degrees out of phase is looking from the middle at both ends at the same time.

This is more than enough to prove that while one end is positive the other is negative or the two signals are in phase with each other. If you are going to look at the scope at least try to understand what you are seeing. Channel A is positive then Channel B is negative meaning that there is one 240 volt signal that you are looking at the two halves of at the same time. They are in phase with each other not opposing each other.
 

Bluebinky

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The same rules apply to DC as AC (except that detailed analysis of AC requires higher math). Voltage by definition is a potential difference (as is subtracting) between two points -- not the addition of two potentials.

For DC (say two car batteries in series with each end measured against the middle): 12.6V - (-12.6V) ==> 25.2V

For AC (say residential wiring with each leg measured against the neutral): 120V@0deg - 120V@180deg ==> 240V (out of phase by definition)

notice that 120V@0deg - 120V@0deg ==> 0V (in phase by definition)
 
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When you get the message "Do you want to leave this page" after clicking Post Reply Click No, do not click Post Reply again.

That should put your post on the server.

Then close the page, you may get "Do you want to leave this page" again, Click Yes.

It works something like that but is hard for me to splain.


Good Luck.

I appreciate it. I do hate to clutter the place up.
 

DonL

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The same rules apply to DC as AC (except that detailed analysis of AC requires higher math). Voltage by definition is a potential difference (as is subtracting) between two points -- not the addition of two potentials.

For DC (say two car batteries in series with each end measured against the middle): 12.6V - (-12.6V) ==> 25.2V

For AC (say residential wiring with each leg measured against the neutral): 120V@0deg - 120V@180deg ==> 240V (out of phase by definition)

notice that 120V@0deg - 120V@0deg ==> 0V (in phase by definition)


Now I am confused.
 

DonL

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Even Newton knew the law of physics with the apple thing, but when he discovered figs, he sold a product to Nabisco. As to this sine wave issue, I'm going to remain Neutral. Too much talk; I'm so confused.


Why not come out and play ?

That waveform does not look like it is measuring 120 or 240V.

And is not measuring 60 cycles, from what I can tell.


It must be a smoke screen.
 

BobL43

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Why not come out and play ?

That waveform does not look like it is measuring 120 or 240V.

And is not measuring 60 cycles, from what I can tell.


It must be a smoke screen.
Why?, I haven't used a scope in 4 years. I use Listerine Cool Mint these days

yeah the ms is off a bit, or the screen scaling per division is confusing me:cool:. I was using an old Sony/Tektronics blue one. Now my Listerine is Blue, or is it green? I'm old, I forget these details. Need to find my teeth. Did you steal them Don? :eek:
 

JWelectric

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The same rules apply to DC as AC (except that detailed analysis of AC requires higher math). Voltage by definition is a potential difference (as is subtracting) between two points -- not the addition of two potentials.
This is very true and the basis of my side of the discussion. The 240 AC is just like the 3 volt two cell flashlight. When we look at the two cell flash light we see +-+- as we transvers from one end to the other end just like we see +-+- 0on the 240 volt winding.

For DC (say two car batteries in series with each end measured against the middle): 12.6V - (-12.6V) ==> 25.2V
connect the two batteries in the manner in which you have outlined in this statement and use you meter to the two remaining post and the reading will be zero not 25.2 but should you connect them +-+- and read then there would be 25.2 volts and the batteries would be in phase with each other just as the winding of the transformer.

For AC (say residential wiring with each leg measured against the neutral): 120V@0deg - 120V@180deg ==> 240V (out of phase by definition)
Connect the scope to the two ends of the winding and you will see one sine wave of 240 volts so now explain how somehow this sine wave splits into two different directions and becomes two sine waves that are going in two different directions. This is impossible to happen.

notice that 120V@0deg - 120V@0deg ==> 0V (in phase by definition)
Just like the two cells of the flashlight should you take the reading from one of the windings to the other end of the winding you will read a voltage of 240 volts. This can be added using vector math as from A to N is 120 volts and from N to B is the other 120 volts. What you are trying your best to do is to measure from N to A, 120 volts and from N to B 120 volts and stand pat that this is the only way to do the math. Yes these two vectors will add up to 240 volts just as if we installed the two cells into the flash light by inserting them +--+ and should we take a reading from – to either + we will have a volt and a half but nothing from end to end. Inserted +--+ the two cells are 180 degrees out of phase with each other and this same thing would happen if the two halves of the transformer were 180 degrees with each other, the reading from end to end would be zero.

The very name of the type of panel we have in our homes tells us that there is only one phase present. Most homes have a 240 volt single phase panel not a two phase 120 volt panel.

When doing vector math where we have three points in a straight line we can measure the distance to the furthest points in three different ways. Say these three points are labeled A,B, and C. The distance measured from A to C is 100 feet. The distance measured from C to A is 100 feet. Then measure from B to either A or C and they will add up to be 100 feet. Just because we measure from B to one of the other points in no way means that B is the starting point of the path of travel and it sure doesn’t mean that a single phase transformer has two phases that are 180 degrees out of phase to make this single phase.

What if means is that if the two 120 voltages were 180 degrees out of phase then the neutral of a multiwire circuit would be carrying the total amperage of both voltages instead of canceling out. This is by definition of 180 degrees out of phase.
 

Reach4

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What if means is that if the two 120 voltages were 180 degrees out of phase then the neutral of a multiwire circuit would be carrying the total amperage of both voltages instead of canceling out. This is by definition of 180 degrees out of phase.

I agree except for the bold bit.

The neutral does carry the sum of the currents through the 120 VAC loads on each leg. If the magnitude of the currents through resistive loads on both legs are equal, the sum will add to zero-- because the two currents are 180 degrees out of phase.
 

Bluebinky

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This is very true and the basis of my side of the discussion. The 240 AC is just like the 3 volt two cell flashlight. When we look at the two cell flash light we see +-+- as we transvers from one end to the other end just like we see +-+- 0on the 240 volt winding.

connect the two batteries in the manner in which you have outlined in this statement and use you meter to the two remaining post and the reading will be zero not 25.2 but should you connect them +-+- and read then there would be 25.2 volts and the batteries would be in phase with each other just as the winding of the transformer.

Connect the scope to the two ends of the winding and you will see one sine wave of 240 volts so now explain how somehow this sine wave splits into two different directions and becomes two sine waves that are going in two different directions. This is impossible to happen.

Just like the two cells of the flashlight should you take the reading from one of the windings to the other end of the winding you will read a voltage of 240 volts. This can be added using vector math as from A to N is 120 volts and from N to B is the other 120 volts. What you are trying your best to do is to measure from N to A, 120 volts and from N to B 120 volts and stand pat that this is the only way to do the math. Yes these two vectors will add up to 240 volts just as if we installed the two cells into the flash light by inserting them +--+ and should we take a reading from – to either + we will have a volt and a half but nothing from end to end. Inserted +--+ the two cells are 180 degrees out of phase with each other and this same thing would happen if the two halves of the transformer were 180 degrees with each other, the reading from end to end would be zero.

The very name of the type of panel we have in our homes tells us that there is only one phase present. Most homes have a 240 volt single phase panel not a two phase 120 volt panel.

When doing vector math where we have three points in a straight line we can measure the distance to the furthest points in three different ways. Say these three points are labeled A,B, and C. The distance measured from A to C is 100 feet. The distance measured from C to A is 100 feet. Then measure from B to either A or C and they will add up to be 100 feet. Just because we measure from B to one of the other points in no way means that B is the starting point of the path of travel and it sure doesn’t mean that a single phase transformer has two phases that are 180 degrees out of phase to make this single phase.

What if means is that if the two 120 voltages were 180 degrees out of phase then the neutral of a multiwire circuit would be carrying the total amperage of both voltages instead of canceling out. This is by definition of 180 degrees out of phase.
The one thing you have correct is the part about single phase 240V and no one here is saying otherwise. You keep referring to "vector math", but are mistaken in saying that the (voltage) difference between two vectors is calculated by adding. You must subtract one from the other, not add.
 

Bluebinky

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This is very true and the basis of my side of the discussion. The 240 AC is just like the 3 volt two cell flashlight. When we look at the two cell flash light we see +-+- as we transvers from one end to the other end just like we see +-+- 0on the 240 volt winding.

connect the two batteries in the manner in which you have outlined in this statement and use you meter to the two remaining post and the reading will be zero not 25.2 but should you connect them +-+- and read then there would be 25.2 volts and the batteries would be in phase with each other just as the winding of the transformer.

Connect the scope to the two ends of the winding and you will see one sine wave of 240 volts so now explain how somehow this sine wave splits into two different directions and becomes two sine waves that are going in two different directions. This is impossible to happen.

Just like the two cells of the flashlight should you take the reading from one of the windings to the other end of the winding you will read a voltage of 240 volts. This can be added using vector math as from A to N is 120 volts and from N to B is the other 120 volts. What you are trying your best to do is to measure from N to A, 120 volts and from N to B 120 volts and stand pat that this is the only way to do the math. Yes these two vectors will add up to 240 volts just as if we installed the two cells into the flash light by inserting them +--+ and should we take a reading from – to either + we will have a volt and a half but nothing from end to end. Inserted +--+ the two cells are 180 degrees out of phase with each other and this same thing would happen if the two halves of the transformer were 180 degrees with each other, the reading from end to end would be zero.

The very name of the type of panel we have in our homes tells us that there is only one phase present. Most homes have a 240 volt single phase panel not a two phase 120 volt panel.

When doing vector math where we have three points in a straight line we can measure the distance to the furthest points in three different ways. Say these three points are labeled A,B, and C. The distance measured from A to C is 100 feet. The distance measured from C to A is 100 feet. Then measure from B to either A or C and they will add up to be 100 feet. Just because we measure from B to one of the other points in no way means that B is the starting point of the path of travel and it sure doesn’t mean that a single phase transformer has two phases that are 180 degrees out of phase to make this single phase.

What if means is that if the two 120 voltages were 180 degrees out of phase then the neutral of a multiwire circuit would be carrying the total amperage of both voltages instead of canceling out. This is by definition of 180 degrees out of phase.
\
The one thing you have right is the single phase panel -- no one is saying otherwise.

Please re-read my post about the batteries with the understanding that they are connected as you describe.

Since you keep referring to "vector math" ... To get the voltage between two vectors which are relative to some common reference, you need to subtract one from the other, not add them ... If the vectors are the same phase and amplitude, you will get zero.

The funny thing is that us Engineers are often picked on for dropping minus signs to simplify calculations (leading to notations with current flowing from positive to negative).
 
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