120/208, 1Ph, 3 Wire

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M

MAC702

Senior Member
Location
Clark County, NV
jumper said:
Noooooo, do not mention 2 phase. That is a whole different system here.

This is called single phase derived from 2 poles of a three phase system.

Why?

It just is, trust me. Confusing but true.
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The way I explain it is "how many different ways can you get pole-to-pole?

Single phase therefore requires two of the poles.
Three-phase requires all three.

I did research the old "two-phase" systems. They used 4 conductors and were basically two separate single phase circuits created out of phase with each other if I'm describing that in a way that didn't make things worse.
 
kwired

kwired

Electron manager
Location
NE Nebraska
MAC702 said:
The way I explain it is "how many different ways can you get pole-to-pole?

Single phase therefore requires two of the poles.
Three-phase requires all three.

I did research the old "two-phase" systems. They used 4 conductors and were basically two separate single phase circuits created out of phase with each other if I'm describing that in a way that didn't make things worse.
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2 phase can be 3, 4 or 5 wires. Still two separate single phases 90 degrees out of phase from one another, but 3 and 5 wire versions have a "common" that ties each coil together. 3 wire common is at one end of each coil, 5 wire midpoint of each coil is tied together.
 
jumper

jumper

Senior Member
Location
3 Hr 2 Min from Winged Horses
kwired said:
2 phase can be 3, 4 or 5 wires. Still two separate single phases 90 degrees out of phase from one another, but 3 and 5 wire versions have a "common" that ties each coil together. 3 wire common is at one end of each coil, 5 wire midpoint of each coil is tied together.
Click to expand...

I've decided that 2 phase does not truly exist.

Y'all made it up just to drive me bonkers.

Not very nice IMO.

:)
 
Besoeker

Besoeker

Senior Member
Location
UK
electrofelon said:
No, that is the correct designation. I know you don't like it. How about go for a walk with that handsome dog of yours and forget all about it :)
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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.......:)
 
M

MAC702

Senior Member
Location
Clark County, NV
kwired said:
2 phase can be 3, 4 or 5 wires. Still two separate single phases 90 degrees out of phase from one another, but 3 and 5 wire versions have a "common" that ties each coil together. 3 wire common is at one end of each coil, 5 wire midpoint of each coil is tied together.
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That actually makes perfect sense.
 
G

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Consulting Electrical Engineer - Photovoltaic Systems
Besoeker said:
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.......:)
Click to expand...

There is a difference between phase shift and phase inversion.
 
kwired

kwired

Electron manager
Location
NE Nebraska
jumper said:
I've decided that 2 phase does not truly exist.

Y'all made it up just to drive me bonkers.

Not very nice IMO.

:)
Click to expand...
I have yet to see a real two phase system myself - and probably won't unless I go east.

Philly area is where you are most likely to run into them from my understanding.

That said single phase induction motors are pretty much "two phase" design, with the phase shift happening at the motor and not at the source.
 
Besoeker

Besoeker

Senior Member
Location
UK
Tony S said:
A bit late. We did and still do use 2Ph.
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Chapter 8 of the J&P goes into the Scott and Le Blanc connections in some detail.
So yes, obviously they obviously exist. But, I think, not very common. I don't think I've ever come across either and certainly never used one on any of the projects we designed.
 
G

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Consulting Electrical Engineer - Photovoltaic Systems
Besoeker said:
Not sure what point you are making WRT to line to line and line to neutral voltages?
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This comes up a lot in audio; many folks call the complementary lines of a balanced circuit "180 degrees out of phase" but if that's what it was the shift in time for every frequency would have to be different. In "pure" 60Hz the difference isn't as significant, although for L1 and L2 to be 180 out a spike on one line would not be seen on the other until 1/120 sec later. Inversion is not the same as phase shift.
 
Besoeker

Besoeker

Senior Member
Location
UK
ggunn said:
This comes up a lot in audio; many folks call the complementary lines of a balanced circuit "180 degrees out of phase" but if that's what it was the shift in time for every frequency would have to be different. In "pure" 60Hz the difference isn't as significant, although for L1 and L2 to be 180 out a spike on one line would not be seen on the other until 1/120 sec later. Inversion is not the same as phase shift.
Click to expand...
Different topic. A 180 shift doesn't apply.
 
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