240v debate....

[iwire]

And your posting to me wasn't an attempt to belittle and I didn't simply throw it back in your face? Look at your contributions to this thread before you answer that.

Don't step in front of a moving truck if you don't wish to get run over. Don't throw a stone if you don't expect a rock to be thrown back. Don't run with the big horses if you can't p**** on the tall timbers.

You knowingly enter into a discussion that you admit is over your head, and when you mock me, you complain that I return with condescension? If you asked me to hand you a 1/2" wrench and I gave you a screwdriver, you don't think you would respond in a similar tone?

Rick, man or man.

You just can't help but shoot yourself in the foot can you?

You consider yourself a truck that is going to run over me. :lol::lol::lol::lol::lol:

 

[jwelectric]

I told you if you did not understand post #98 and #290 you would not be able to follow along. I will simply refer you back to those instead of repeating it all over.

OK. Let's try walking through it step by step:First, we know that we can link single-phase generators to get multiple phases.

As I have already pointed out I am not interested in discussing generators or multiple phases I am only interested in talking about a single phase center tap transformer.
I am not looking toward going to engineering school just looking for a simple answer to a simple question that is covered in a 150 hour basic electric class.
A question that I am required to answer to people who do not have a high school education and has worked either in textile or furniture all their lives and are looking for a trade to enter quickly and not a career of design. You know just plain old everyday run of the mill people.

I do not have the time to go into the physics of current flow of the different aspects of design but I do need to address the power delivered to our homes daily and ensure that the student has some sort of understanding of the theory of a single phase service.

To do this I show a short video of how a single phase transformer is made. You know the one on top of the pole outside your home, the one that produces a 120/240 volt ?single? phase. The magnetic field of the primary energizes the core of the transformer which induces current in the secondary. You know the type, the one with only one alternating magnetic field.

When this transformer loses its neutral then it can only deliver 240 volts to our homes but it makes everything in the home a series 240 volt circuit. If this was a service of two phases of 120 that was 180 degrees out of phase with each other one would cancel out the other and no current would flow just as the reversed battery in a two cell flashlight.

 

[jwelectric]

Zero of course.




On the two ungrounded conductors.



Could it? most certainly.

Being 180 out phase with each other is is the only way it could take place.

Bob
I know that you know better than this.
The magnetic field of the primary energizes the core of the transformer which induces current in the secondary. You know the type, the one with only one alternating magnetic field.

 

[mivey]

You "can", but you are the one that said you "MUST" (your emphasis). Now you're backpedling and it is a "can" not a "must"?

What in the world are you talking about?

The "can" had to do with what node you pick. A node does not have a potential all by itself as the potential is relative to another node. I know you know this so why the merry-go-round?

The "must" has to do with the voltage (the potential difference between two nodes). And yes, you MUST have a common reference if you are going to discern the difference between them. The best you can do withouit a common reference is discuss the difference in their magnitudes, but that does not give you a full comparison. We have been discussing the phase relationships, magnitudes, summed voltages, etc. and to do that you MUST have a common reference.

 

[mivey]

As I have already pointed out I am not interested in discussing generators or multiple phases I am only interested in talking about a single phase center tap transformer.

You don't know what you don't know. There are basic concepts about voltages and directions and polarity you should understand. If you choose not to, that is certainly your option.

I am not looking toward going to engineering school just looking for a simple answer to a simple question that is covered in a 150 hour basic electric class.
A question that I am required to answer to people who do not have a high school education and has worked either in textile or furniture all their lives and are looking for a trade to enter quickly and not a career of design. You know just plain old everyday run of the mill people.

I do not have the time to go into the physics of current flow of the different aspects of design but I do need to address the power delivered to our homes daily and ensure that the student has some sort of understanding of the theory of a single phase service.

Before you can write, you have to know your ABCs. As much as you want to skip that step, it simply is a pre-requisite.

To do this I show a short video of how a single phase transformer is made. You know the one on top of the pole outside your home, the one that produces a 120/240 volt ?single? phase. The magnetic field of the primary energizes the core of the transformer which induces current in the secondary. You know the type, the one with only one alternating magnetic field.

When this transformer loses its neutral then it can only deliver 240 volts to our homes but it makes everything in the home a series 240 volt circuit. If this was a service of two phases of 120 that was 180 degrees out of phase with each other one would cancel out the other and no current would flow just as the reversed battery in a two cell flashlight.

Again, a three-terminal supply is not the same as a two-terminal supply. The reversed battery is not the same as an AC source. You keep thinking they are because you have not learned your ABCs. If you do not learn the fundamentals, you will never understand. Sorry, but that is just the way it is.

 

[mivey]

Bob
I know that you know better than this.

He meant out of phase relative to the Earthed neutral of course. Most people in the world think of Earth as a pretty good reference.

What point is there in purposely trying to misunderstand a post? How does that help communicate? Sometimes it might be good for a laugh but other than that...

The magnetic field of the primary energizes the core of the transformer which induces current in the secondary. You know the type, the one with only one alternating magnetic field.

Yeah, the source that reverses polarity every 1/2 cycle.

 

[iwire]

Bob
I know that you know better than this.

He meant out of phase relative to the Earthed neutral of course. Most people in the world think of Earth as a pretty good reference.

Well, .... thanks mivey for your faith in me but my integrity prevents me from going along with that.

I screwed up plain and simple.

Help me out here, I was thinking that if they were in phase that there would be no potential.

 

[jwelectric]

You don't know what you don't know. There are basic concepts about voltages and directions and polarity you should understand. If you choose not to, that is certainly your option.

First you have no idea of my knowledge and I promise you that I have a full understanding of magnetic induction of a single phase transformer.

Before you can write, you have to know your ABCs. As much as you want to skip that step, it simply is a pre-requisite.

So you are saying that I must teach my students about multiphase transformers and generators before we can understand a single phase transformer. Wonder how the HVAC class ever learns about low voltage of 24 volts.

Again, a three-terminal supply is not the same as a two-terminal supply. The reversed battery is not the same as an AC source. You keep thinking they are because you have not learned your ABCs. If you do not learn the fundamentals, you will never understand. Sorry, but that is just the way it is.

Maybe I haven?t learned about the ABCs but I sure understand a single phase transformer and the magnetic flied that induces the three terminal secondary and the fact that the primary is always a single sine wave which MUST induce a single sine wave in the secondary that changes polarity with the primary but cannot induce two opposing sine waves in the secondary.

Yeah, the source that reverses polarity every 1/2 cycle.

Are you trying to say that this reverse in polarity causes two different opposing sine waves in the secondary?

Help me out here, I was thinking that if they were in phase that there would be no potential.

From line 1 to line 2 of a single phase transformer there is a potential and only one sine wave. Why would a sine wave need to oppose itself to have potential? Think of a two cell flashlight that has the batteries reversing at the rate of 60 times a second. Now we have a two cell AC flashlight. Should we reverse one of the batteries it wouldn?t matter how fast we reversed them no current would flow. The same is true with the AC transformer.

 

[jim dungar]

Time for a time out.

PM me to reopen or start a new thread.