May I ask a question about the single vs two phase stuff

[ggunn]

Somewhat related......
I was at a transformer manufacturer's works in Birmingham (UK Midlands) for a witness test.
The chief tester had a poster with a big fearsome guy behind a desk with his title.
"President of the Pedantic Society".
A little guy had approached the desk.
"Sir, shouldn't that be "President of the Society of Pedants?"

We are the Judean People's Front! People's Front of Judea, PAH!

 

[Little Bill]

If you guys are trying to "Up" the post count then do it by staying on the topic, as tiresome as it has become.

 

[Russs57]

Beating a dead horse I reckon but let’s try the following.

Say you look at five complete cycles of the 240/120 power we are talking about on a dual trace scope (120 to N). To me if it was polarity change we would see what the graphs are that have been posted. If it was 180 shift, we would see a half cycle, then four cycles that look same as polarity change, then another half cycle.

 

[Besoeker]

Beating a dead horse I reckon but let’s try the following.

Say you look at five complete cycles of the 240/120 power we are talking about on a dual trace scope (120 to N). To me if it was polarity change we would see what the graphs are that have been posted. If it was 180 shift, we would see a half cycle, then four cycles that look same as polarity change, then another half cycle.

You have lost me with four cucles that look the same...............:?

 

[jaggedben]

Beating a dead horse I reckon but let’s try the following.

Say you look at five complete cycles of the 240/120 power we are talking about on a dual trace scope (120 to N). To me if it was polarity change we would see what the graphs are that have been posted. If it was 180 shift, we would see a half cycle, then four cycles that look same as polarity change, then another half cycle.

You have lost me with four cucles that look the same...............:?

Russ, I believe you are describing exactly the graphs that Larry posted in post 546.

Half a thread ago. Been there, done that.:slaphead:

Another forum I once frequented actually had a 'beating a dead horse' smiley. We could use that.:lol:

 

[Russs57]

You are right jaggedben. My iPad won’t let me expand pics so I missed it. My bad.

 

[jaggedben]

You are right jaggedben. My iPad won’t let me expand pics so I missed it. My bad.

No worries. What gets me is that it didn't lead to much before. Maybe now we have another chance.

 

[jumper]

You are right jaggedben. My iPad won’t let me expand pics so I missed it. My bad.

Tap on the pics.

 

[Adamjamma]

so basically, we are arguing over wether the phase looks the same for the centertapped coil of the normal 120-n-120 making 240, compared to the 240 in the UK that is also called single phase, and whether 240 USA is actually two phase, right? Because I have seen the centertapped 55 volts as they make 110 here in the UK on a scope, and it looks almost like the one that was shown in the first drawing for 120/240... but I have yet to find someone with a scope hooked up to 240 here in the UK...
Job I had for 90 days was at a manufacturing company that made magnets and had the scopes hooked up to several DC voltages along with a 110 transformer supply.. would have loved to see if there was an actual difference to the scoped values before and after the transformer.....
But, cannot do the tests myself because many years ago I sold my Yaesu scope. Of course, it was part of my FT101E, which I still have..lol

 

[jumper]

so basically, we are arguing over wether the phase looks the same for the centertapped coil of the normal 120-n-120 making 240, compared to the 240 in the UK that is also called single phase, and whether 240 USA is actually two phase, right? Because I have seen the centertapped 55 volts as they make 110 here in the UK on a scope, and it looks almost like the one that was shown in the first drawing for 120/240... but I have yet to find someone with a scope hooked up to 240 here in the UK...
Job I had for 90 days was at a manufacturing company that made magnets and had the scopes hooked up to several DC voltages along with a 110 transformer supply.. would have loved to see if there was an actual difference to the scoped values before and after the transformer.....
But, cannot do the tests myself because many years ago I sold my Yaesu scope. Of course, it was part of my FT101E, which I still have..lol

Adam, you have parts of the argument.

It is going to be very confusing to you to mix UK and USA systems in terminology and context.

UK single phase and USA single phase supplies are completely different. We only use the UK set up in very limited applications as a rule for distribution. Circuit level is different.

 

[Besoeker]

but I have yet to find someone with a scope hooked up to 240 here in the UK...

I've done it many times.
It is simply 230V rms, 325V peak. Nominally.

 

[LarryFine]

so basically, we are arguing over wether the phase looks the same for the centertapped coil of the normal 120-n-120 making 240, compared to the 240 in the UK that is also called single phase, and whether 240 USA is actually two phase, right?

More or less. The UK 240v is one leg of a 3-phase 416Y/240v (although they usually call it 250v, which would be ~430v L-L) system, just like our 208Y/120v system, but we don't use Y systems to deliver 1 leg.

Because I have seen the centertapped 55 volts as they make 110 here in the UK on a scope, and it looks almost like the one that was shown in the first drawing for 120/240... but I have yet to find someone with a scope hooked up to 240 here in the UK...

Except for the voltages, they are the same thing, especially if they ground the center tap.

Job I had for 90 days was at a manufacturing company that made magnets and had the scopes hooked up to several DC voltages along with a 110 transformer supply.. would have loved to see if there was an actual difference to the scoped values before and after the transformer.....

Of course, there would be different voltage levels between primaries and secondaries, except for 1:1 transformers used for isolation purposes. The DC output is almost always higher than the AC input of a rectifier, especially with filter capacitors, as they tend to charge to peak voltage.

 

[Russs57]

Adam, in terms of the USA supply, it is derived from a center tapped secondary. The center tap is grounded. Call the ends L1 and L2 and the center tap N. Voltages from either end to N are 120 and from end to end 240 (@ 60 hertz).

The discussion is if L1 to N is 180 degrees out of phase from L2 to N..........or if L1 to N is reverse polarity from L2 to N. For a pure sine wave either viewpoint is identical in all respects.

Now my sticking point is I view “180 degrees out of phase” as one lags the other by a certain amount of time. Given that in audio, we use the same exact transformer setup to create a signal with reverse polarity I’m saying it has to be that in this case as well. In audio we can’t have a time difference between the two waveforms or our music wouldn’t work too well.

Could be I’m just stuck on terminology as I’m not an EE and some here are.

 

[Besoeker]

More or less. The UK 240v is one leg of a 3-phase 416Y/240v (although they usually call it 250v,

It is nominally 400V/230V.

 

[Russs57]

And do every use it to supply 3 phase 400 VAC?

 

[LarryFine]

And do every use it to supply 3 phase 400 VAC?

In industrial applications, I believe so. I have been told that some larger residential services include two legs, similar to our 120/208v 1ph apartment services.

 

[jumper]

Now my sticking point is I view “180 degrees out of phase” as one lags the other by a certain amount of time. Given that in audio, we use the same exact transformer setup to create a signal with reverse polarity I’m saying it has to be that in this case as well. In audio we can’t have a time difference between the two waveforms or our music wouldn’t work too well.

Could be I’m just stuck on terminology as I’m not an EE and some here are.

Audio and general power analysis of a POCO tranny sine waves are different

We are going approach things differently.

Just like looking at a tranny is different when looking at the primary vs secondary.

 

[Adamjamma]

Ok. I am understanding a bt better now. in some ways easier that step converters and filters to get from 2 Mhz to 150 Mhz in radio work..lol...

Cannot wait to finally get my house built and equipment together in JA... so I can get back to playing with my radio gear on occasion.. home in UK too small to play with radio circuits.

 

[jumper]

Ok. I am understanding a bt better now...

We know it can be quite confusing when we kinda get into this topic, it is a bit touchy.
We have more then one issue at play here.

I do recommend that you differentiate between the UK and US standards, wiring methods, and terminology. At some point ya gotta decide on which you want to qualify for. Both at the same time is gonna be real hard.

 

[ggunn]

Audio and general power analysis of a POCO tranny sine waves are different

We are going approach things differently.

Just like looking at a tranny is different when looking at the primary vs secondary.

In the analog audio world when we use a transformer to create a balanced signal pair from an unbalanced signal we use the same transformer, only it's a whole lot smaller. There is no question that the balanced waveforms thus generated are each the inversion of the other.