MAC702
Senior Member
- Location
- Clark County, NV
Does this help, or make it worse?
120/208, 1Ph, 3 Wire
- Thread starter Sean.Day72
- Start date
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- Occupation
- Licensed Electrician
Does this help, or make it worse?
The windings look like they are reversed.
MAC702
Senior Member
- Location
- Clark County, NV
Ha, I didn't look at that part! Just grabbed the pic off the 'net when I saw the waveforms.
Here's one that ignores the xformer guts. Is this better? Except I prefer the terms Line 1 and Line 2 (or Pole), as the Phase is better described as the path between poles. That's why this is a "single phase."
Last edited:
- Occupation
- Licensed Electrician
Ha, I didn't look at that part! Just grabbed the pic off the 'net when I saw the waveforms.
Here's one that ignores the xformer guts. Is this better?
If you get rid of the voltage numbers you have a good illustration of what single phase voltage is to normal people. And then the fight starts. Everybody can agree what three phase is. Nobody can agree on what single phase is.
Search this forum, which is arguably the best forum on the net with the best minds in the electrical world as members, using keywords "why do they call it single phase" and you will find some of the longest threads ever, never once has there been a satisfactory conclusion. Single phase exists but when it comes time to explain it the smartest people in the world do more than disagree, they disagree with venom.
kwired
Electron manager
- Location
- NE Nebraska
It is a step-up transformer
kwired
Electron manager
- Location
- NE Nebraska
Don't know that I agree with what is on that graph.Ha, I didn't look at that part! Just grabbed the pic off the 'net when I saw the waveforms.
Here's one that ignores the xformer guts. Is this better? Except I prefer the terms Line 1 and Line 2 (or Pole), as the Phase is better described as the path between poles. That's why this is a "single phase."
The volts scale should be from -120 at the bottom to +120 at the top. When one line is +120 it is 120 volts to zero crossing which is where neutral is at and 240 volts to the opposite line
But it is actually more complex then that as what we typically measure 120/240 is actually RMS voltage, the actual peaks would be about 170 volts each side of zero crossing.
It's nonsense. And irrelevant to the point made by the OP.
I think that whoever produced it and those who present it should stick to their day job - writing works of fiction.
Black is line to line. Red & blue are each line to neutral. I'm ok with that.
I totally agree with your comment about RMS vs peak, however.
kwired
Electron manager
- Location
- NE Nebraska
Well it shows three different measurements on same graph, but reality is all three measurements are coming from same voltage wave from the same source.
Disregarding actual peak voltages - it still needs to show -120 on lower end and + 120 on upper end otherwise what is represented is more accurate for 240/480 volts.
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
I disagree, but we'll just leave it at that if it's OK with you.
Feel free to disagree - it is a discussion forum after all.
Just let's be amicable about it.
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
I thought I was. Did I say something to offend you? If so, I apologize.
I thought we both were. Absolutely nothing to apologise for.
MAC702
Senior Member
- Location
- Clark County, NV
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
Mac, bit of advice..take it for what it is worth.
Did you ever read The Odyssey?
At one point in the story the main character attempts to sail his ship between two great perils named Scylla and Charybdis. His ship is sunk and all the crew is killed except him.
If I were you I would abandon the ship/point you are on unless you feeling real brave and incredibly lucky and believe you will survive in a debate on this topic.
As ActionDave said, there are some real heavy hitters here that bring really big guns on this topic.
Just my 2 cents of advice, feel free to ignore it.
Derek
Did you ever read The Odyssey?
At one point in the story the main character attempts to sail his ship between two great perils named Scylla and Charybdis. His ship is sunk and all the crew is killed except him.
If I were you I would abandon the ship/point you are on unless you feeling real brave and incredibly lucky and believe you will survive in a debate on this topic.
As ActionDave said, there are some real heavy hitters here that bring really big guns on this topic.
Just my 2 cents of advice, feel free to ignore it.
Derek
MAC702
Senior Member
- Location
- Clark County, NV
Agreed. The nominal values are not relevant to the relative waves.
mivey
Senior Member
The traditional 2 phase is a subset of a symmetrical 4 phase system. And some systems labeled 2 phase are more correctly called a 4 phase system. Straight out of engineering reference texts.
mivey
Senior Member
So there it is. Labels are not always completely descriptive of a system's physical characteristics. If one tries to make the label match the physical we would need more complex system names and that is really not going to happen.It isn't about liking it or not liking it. One voltage is line to line, the other line to neutral. The two voltages are not in phase. But, call it 1PH if you wish.
And, yes I did walk the dog.......
So we call them by simplified names while keeping an understanding of the physical structure. Unfortunately, those that don't understand the systems can get confused by the simplified labels.
When classifying polyphase systems and subsets of polyphase systems, voltages of the same magnitude are grouped together. As far as grouping goes, line to line and line to neutral are in two different systems of voltages.
So there are two phases present for the line to neutral voltage system but it does not have the system label "2 phase" as that is a name reserved for a quadrature displacement.
There is one phase present for the line to line voltage system. Definately a single phase there.
In the canonical classification, every voltage (any set of two terminals or reference points can only be counted once) is in the same system classification and the number of different phase positions present at a given point in time is the number of phases present in the system. The label we use may not match the physical structure.
mivey
Senior Member
The label is just a label. It does not change the physics of what is present.
mivey
Senior Member
Quite. This thread is about a 120 degree shift.
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