buffalonymann
Senior Member
- Location
- NC
Apparently I am required to start a new thread. So please be more specific when you say they're 180 degrees out of phase, what is out of phase?
bsoeker single or two phase
- Thread starter buffalonymann
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Nothing is really out of phase, it's just opposite ends of a single winding center tapped and one is positive while the other is negative.
Roger
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Phase in this sense is a relative term. At one moment in time, when compared to the neutral, one phase, or line conductor, is at positive peak at the same moment the other line conductor is at negative peak. Therefore, they are of opposite polarity, which is what is meant by being "180 degrees out of phase."
In comparison, with three-phase, at one moment in time, one line conductor is at positive peak voltage while the other two are negative, but not at peak, with one of them rising in voltage toward negative peak while the other is declining in voltage away from negative peak. The three are 120 degrees out of phase.
In comparison, with three-phase, at one moment in time, one line conductor is at positive peak voltage while the other two are negative, but not at peak, with one of them rising in voltage toward negative peak while the other is declining in voltage away from negative peak. The three are 120 degrees out of phase.
gar
Senior Member
- Location
- Ann Arbor, Michigan
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- EE
180720-2041 EDT
Larry Fine:
Your response is very good. I wish more people could understand that.
.
Larry Fine:
Your response is very good. I wish more people could understand that.
.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Tony S
Senior Member
- Location
- Resting under the Major Oak UK
I’ve almost given up trying to explain split phase to UK electricians, it’s not something that is regularly used over here. Farms in the middle of nowhere are the most likely places to find it.
UKPN (UK Power Networks) stores inventory only list a few 250V→N→250V transformers as approved for installation.
Personally I’ve never come across them but I’ve had a few phone calls asking for help.
buffalonymann
Senior Member
- Location
- NC
Furthermore, please explain why it is not possible to start an induction motor wound for 2 phase with single phase center tapped transformer with the use of starting apparatus
buffalonymann
Senior Member
- Location
- NC
It is not "one phase or line conductor" it is a single phase xfmr. they are not 180 out of phase it is alternating current. that's like saying a battery plus and minus is 180 degrees out of phase - no such thing. they are opposite polarity and the current is always flowing in the same direction from l1 to l2 and then in the reverse. This my friend is why it could only be single phase and nothing more. And also the reason why you cannot start an induction motor without the use of starting apparatus. However you can start an induction motor with a two phase current system
- Occupation
- Licensed Electrician
What do you mean by "starting apparatus"?
buffalonymann
Senior Member
- Location
- NC
starting capacitor/ start winding - have you noticed three phase motors do not need that apparatus? Neither does two phase system. Single phase does, even when its centered tapped and called two phase
those who claim single phase with a centered is two phase simply do not understand electrical theory
buffalonymann
Senior Member
- Location
- NC
Split phase is the appropriate term :thumbsup:
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Because 2-phase supplies have two 2-wire circuits with a 90-degree offset between them, and thus can be used to create a rotating magnetic field. A capacitor is used in a single-phase motor to create the same rotating magnetic field.
- Occupation
- Licensed Electrician
starting capacitor/ start winding - have you noticed three phase motors do not need that apparatus? Neither does two phase system. Single phase does, even when its centered tapped and called two phase
those who claim single phase with a centered is two phase simply do not understand electrical theory
You can run a two phase motor off a high leg delta system if you wire it high leg to center tap neutral.
- Occupation
- Licensed Electrician
The nitpickers are gonna be all over you like white on a golf ball within the next twenty for hours.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Read my post again. I did not say what you think I said, I said that is "what is meant by being '180 degrees out of phase.'" I was explaining what the incorrect terminology really means.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Do you disagree that the run cap is used to create what mimics 2ph from 1ph? A shaded-pole motor does the same thing with the shading coils.
- Occupation
- Licensed Electrician
I agree completely, but I am in the reasonable camp of members who participate here. The nitpickers are an entirely different breed.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Well, as long as we agree.
buffalonymann
Senior Member
- Location
- NC
That is correct and that is the difference between single phase and two phase. A center-tapped single phase xfmr is not two phases
buffalonymann
Senior Member
- Location
- NC
Well, as long as we agree.
the picture they presented and were high fiving each other like school girls is not right either. the current flows from l1 to l2 at a given point, which means the voltage polarity is the same in both haves of the xfmr. both l1 to ct and l2 to ct rise and fall synchronously.
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