jimwalker
Senior Member
- Location
- TAMPA FLORIDA
On a school i am now wiring only single phase is available.To get us 3 phase Y no high leg all POCO (TECO) needs to add is 1 more hot leg.So do i really have 2 phase now ???? 
Is single phase 120/240 really 2 phase ?
- Thread starter jimwalker
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electricman2
Senior Member
- Location
- North Carolina
- Occupation
- Retired Electrical Contractor
Re: Is single phase 120/240 really 2 phase ?
No, it is still single phase. Even though they would only add one ungrounded conductor to have a three phase service. Each conductor would carry two of the three phases.
No, it is still single phase. Even though they would only add one ungrounded conductor to have a three phase service. Each conductor would carry two of the three phases.
jimwalker
Senior Member
- Location
- TAMPA FLORIDA
Re: Is single phase 120/240 really 2 phase ?
a drawing on this would be helpfull.Iam sure it will work but find it hard to understand.I now have from only one hot wire a system with 120 volts ground to hot ,240 hot to hot ,and 180 degrees out of phase (2 phases ? )
a drawing on this would be helpfull.Iam sure it will work but find it hard to understand.I now have from only one hot wire a system with 120 volts ground to hot ,240 hot to hot ,and 180 degrees out of phase (2 phases ? )
electricman2
Senior Member
- Location
- North Carolina
- Occupation
- Retired Electrical Contractor
Re: Is single phase 120/240 really 2 phase ?
Maybe Tom, Charlie or someone has a graphic they can post on this.
Maybe Tom, Charlie or someone has a graphic they can post on this.
bphgravity
Senior Member
- Location
- Florida
Re: Is single phase 120/240 really 2 phase ?
Instead of thinking in terms of how many wires there are or how they are connected, think of the electromagnetic and magnetomotive forces that are created in a single-phase system verses a 2-phase or 3-phase system.
In a single-phase transformer, the flux in the magnetic circuit are in phase, whereas a polyphase system has two or three magnetic circuits through the core and the flux in the various circuits are displaced in phase.
Its an issue of time. A 3-phase system as three alternating single-phase currents of equal frequency and amplitude, but differing in phase from each other by one-third of a period. The time period is the same with a 3-wire 120V/240V system.
Instead of thinking in terms of how many wires there are or how they are connected, think of the electromagnetic and magnetomotive forces that are created in a single-phase system verses a 2-phase or 3-phase system.
In a single-phase transformer, the flux in the magnetic circuit are in phase, whereas a polyphase system has two or three magnetic circuits through the core and the flux in the various circuits are displaced in phase.
Its an issue of time. A 3-phase system as three alternating single-phase currents of equal frequency and amplitude, but differing in phase from each other by one-third of a period. The time period is the same with a 3-wire 120V/240V system.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Re: Is single phase 120/240 really 2 phase ?
I like to think of it like counting pairs of cards in cribbage.
2 of a kind = 1 pair -> 2 hot conductors = 1 phase
3 of a kind = 3 pairs -> 3 hot conductors = 3 phases
I like to think of it like counting pairs of cards in cribbage.
2 of a kind = 1 pair -> 2 hot conductors = 1 phase
3 of a kind = 3 pairs -> 3 hot conductors = 3 phases
B
bthielen
Guest
Re: Is single phase 120/240 really 2 phase ?
Good analogy, Jim. I was trying to think of a simple way to draw a verbal picture and you hit the nail right on the head.
It's not the number of wires but the number of relationships that determine the phasing.
Bob
Good analogy, Jim. I was trying to think of a simple way to draw a verbal picture and you hit the nail right on the head.
It's not the number of wires but the number of relationships that determine the phasing.
Bob
jimwalker
Senior Member
- Location
- TAMPA FLORIDA
Re: Is single phase 120/240 really 2 phase ?
thanks Roger that helped some
thanks Roger that helped some
Re: Is single phase 120/240 really 2 phase ?
You're welcome Jim.
I know you know most of this information, but click here for another good site, just use the index on the left to navigate through it.
Roger
You're welcome Jim.
I know you know most of this information, but click here for another good site, just use the index on the left to navigate through it.
Roger
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