Connect with us

Closed Delta 120/240V 3-phase service

Discussion in 'Electrical Engineering' started by Beachcomber, Feb 10, 2008.

Scroll to continue with content
  1. krw

    krw Guest

    The transformers aren't on every pole (every third), but the wires
    are. I see it all over. All you have to do is look.
    Everywhere I've lived (some underground).
     
  2. Don Kelly

    Don Kelly Guest

    ----------------------------
    -----------------
    There are many places where a single phase is run down an alley (the next
    alley is on another phase so that the total district load is pretty well
    balanced across the 3 phases. This is true in residential districts in many
    cities which exceed 1,000,000 inhabitants. Simply a matter of economics in
    situations where high heating or, more likely, cooling electrical
    demands are not present. Where I am, a 3 phase main feeder is across the
    street but a single phase feed from this line serves the whole of a small
    subdivision. There is simply no need for running 3 phases (particularly
    underground) as loads don't warrant it in this case. In a previous home, 3
    phase was down the alley but only because there was a commercial load at the
    end of the street which warranted the 3 phase feeder.

    There is no "one size fits all" solution so no BS is involved-just different
    observations in different places.
     
  3. krw

    krw Guest

    Even the purely residential area I grew up in had all three phases
    on the pole (one pig per pole - four houses per pole).
    Everywhere I've looked but *very* rural areas has three phase
    distribution.
     
  4. Guest

    | In article <>,
    | says...
    |> In article <>,
    |> > obviously very different practices on different sides of the pond.
    |> > Virtually all residential distribution over here is 3 phase. The only
    |> > time I've ever spotted single phase is when an isolated property has its
    |> > own transformer.
    |>
    |> I just wish I had three-phase into my house.
    |
    | Different issue. My father wanted three phase into his house in the
    | late '50s. He argued that it was on top of the pole already so it
    | was a simple matter to bring it down to the entrance panel. They
    | told him that they would do it if he guaranteed a $100/month bill
    | (rather steep for the '50s).

    There is, afterall, a cost to keep 2 more pole pigs up there. Those things
    are not cheap.
     
  5. Guest

    | In article <fpgbtj$2g3$>, says...
    |>
    |> >Look again (open your eyes this time). You're not seeing the forest
    |> >for the trees. It *IS* on top of 90% of the poles in the country.
    |> >The other 10% are single phase only, generally found only in rural
    |> >areas.
    |>
    |> Really?
    |
    | Really!
    |
    |> In all of the places I've lived, residential areas had
    |> single-phase service only: a single MV line running down the top of the
    |> poles along the street or alley, and single-phase transformers
    |> providing center-tapped 120/240 service to several houses per
    |> transformer.
    |
    | Where do you live, Mongolia? The only places I've seen single phase
    | distribution is in the middle of the country (rural Vermont, in
    | fact).

    MV comes out of substations in three phase. The distribution trunks
    are three phase. But many side branches, particularly residential
    areas, are single phase MV. So everyone on the same street is on the
    same phase. Big deal. The utility saves money doing that and can
    keep things in balance by putting the next street on a different phase.


    |> Three-phase distribution is used for large customers
    |> only.
    |
    | Bullshit!

    Of course in the distribution design, three phase goes all over the place
    because there might be scattered need for three phase. And then they have
    to keep it reasonably balanced where it does go, so the single phase lines
    branching off or going to a direct service are balanced over these phases.


    |> Given the amount of area covered by single-family houses
    |> compared to the area used by commercial/industrial/large residential
    |> (high rise), I'd have to guess that more than 50% of the total number
    |> of poles that have any transformers carry one single-phase
    |> transformer.
    |
    | Your *guess* is wrong.

    Actually this is quite common. Even if three phase distribution goes
    through a residential area, the transformers on the poles for homes
    along the way are usually just one transformer supplying one phase to
    that bunch of homes.
     
  6. Guest

    | In article <fpihpi$34u$>, says...
    |>
    |> >> In all of the places I've lived, residential areas had
    |> >> single-phase service only: a single MV line running down the top of the
    |> >> poles along the street or alley, and single-phase transformers
    |> >> providing center-tapped 120/240 service to several houses per
    |> >> transformer.
    |>
    |> >Where do you live, Mongolia? The only places I've seen single phase
    |> >distribution is in the middle of the country (rural Vermont, in
    |> >fact).
    |>
    |> Currently, the area around Vancouver BC. Other residential areas with
    |> single-phase service: near Waterloo, Toronto, and St. Catharines
    |> Ontario, near Montreal Quebec.
    |>
    |> Where do you live that has full three-phase MV on top of every pole on
    |> every street in a residential area? And three transformers on every
    |> pole that has a transformer?
    |
    | The transformers aren't on every pole (every third), but the wires
    | are. I see it all over. All you have to do is look.

    There are lots of distribution lines with all three phases. There are
    also lots with just one phase. Either way, just one transformer is the
    norm for residential services.


    |> >> Given the amount of area covered by single-family houses
    |> >> compared to the area used by commercial/industrial/large residential
    |> >> (high rise), I'd have to guess that more than 50% of the total number
    |> >> of poles that have any transformers carry one single-phase
    |> >> transformer.
    |>
    |> >Your *guess* is wrong.
    |>
    |> Not where I live now, nor where I've lived for decades. Again, where do
    |> you live that has 3-phase on the pole outside every house?
    |
    | Everywhere I've lived (some underground).

    You manage to only live in strange places.
     
  7. Guest

    | Even the purely residential area I grew up in had all three phases
    | on the pole (one pig per pole - four houses per pole).

    One house I lived in a long time ago had only single phase MV on it.
    Another around the corner (after we moved) had three phase MV on it.
    One pole pig served 3 homes single phase. The three phase then ran
    on down the street and branched off to a school which had three very
    large pole pigs. I went to grade school there and by 5th grade knew
    that was for three phase power (but I didn't yet know the difference
    between delta and wye).

    Where I live now has a single phase MV branch running down about 6
    poles and then goes underground to serve 3 pad mounts. It comes off
    a three phase MV trunk that goes to a college about 4 miles north.

    If I wanted three phase power here, it would be VERY expensive to get.
     
  8. I *have* looked where I live. I've told you what I see (a single MV
    wire on the top of the vast majority of poles in residential areas).
    The next level up the distribution hierarchy is 3-phase, so 3-phase
    lines do pass through residential areas, but only one phase is tapped
    for the line of poles down each street or alley.

    Again, where do you see 3-phase on every pole? Tell us some places.
    Even when there are 3 phases, do the transformers occur in groups of 3?
    Or do you mostly get one transformer per pole, tapping only one of the
    3-phase MV lines? (That's what I see when there does happen to be
    3-phase distribution).
    And where would that be? City or suburbs?

    Dave
     
  9. krw

    krw Guest

    Good grief, Phil! Read! It's not distribution, rather service!
    The three secondary phases *ARE* on the poles.
    Nope, Midwest, Northeast/New England, but I see it everywhere.
     
  10. krw

    krw Guest

    Try reading Phil. The pigs were already there! Three-phase was
    already available on the pole; only the drop and meter were needed.
     
  11. krw

    krw Guest

    Illinois, New York, Vermont (haven't looked here in OH).
    One pig per pole, three wires going between poles, under the MV
    lines.
    <shrug> City (and state) not big enough to have suburbs.
     
  12. Guest

    | In article <>, phil-news-
    | says...
    |> | In article <>,
    |> | says...
    |> |> In article <>,
    |> |> > obviously very different practices on different sides of the pond.
    |> |> > Virtually all residential distribution over here is 3 phase. The only
    |> |> > time I've ever spotted single phase is when an isolated property has its
    |> |> > own transformer.
    |> |>
    |> |> I just wish I had three-phase into my house.
    |> |
    |> | Different issue. My father wanted three phase into his house in the
    |> | late '50s. He argued that it was on top of the pole already so it
    |> | was a simple matter to bring it down to the entrance panel. They
    |> | told him that they would do it if he guaranteed a $100/month bill
    |> | (rather steep for the '50s).
    |>
    |> There is, afterall, a cost to keep 2 more pole pigs up there. Those things
    |> are not cheap.
    |
    | Try reading Phil. The pigs were already there! Three-phase was
    | already available on the pole; only the drop and meter were needed.

    Try getting a handle on business and economics. The cost of _using_ the
    equipment has to be paid for. There are costs of maintenance and replacing
    things that break. If the transformer blows up, the utility replaces it.
    If it is shared between two businesses, they share the costs. This is not
    a freebie ... except for the base level of service required for residences.
     
  13. Guest

    | In article <>, phil-news-
    | says...
    |> | In article <fpihpi$34u$>, says...
    |> |>
    |> |> >> In all of the places I've lived, residential areas had
    |> |> >> single-phase service only: a single MV line running down the top of the
    |> |> >> poles along the street or alley, and single-phase transformers
    |> |> >> providing center-tapped 120/240 service to several houses per
    |> |> >> transformer.
    |> |>
    |> |> >Where do you live, Mongolia? The only places I've seen single phase
    |> |> >distribution is in the middle of the country (rural Vermont, in
    |> |> >fact).
    |> |>
    |> |> Currently, the area around Vancouver BC. Other residential areas with
    |> |> single-phase service: near Waterloo, Toronto, and St. Catharines
    |> |> Ontario, near Montreal Quebec.
    |> |>
    |> |> Where do you live that has full three-phase MV on top of every pole on
    |> |> every street in a residential area? And three transformers on every
    |> |> pole that has a transformer?
    |> |
    |> | The transformers aren't on every pole (every third), but the wires
    |> | are. I see it all over. All you have to do is look.
    |>
    |> There are lots of distribution lines with all three phases. There are
    |> also lots with just one phase. Either way, just one transformer is the
    |> norm for residential services.
    |
    | Good grief, Phil! Read! It's not distribution, rather service!
    | The three secondary phases *ARE* on the poles.
    |
    |> |> >> Given the amount of area covered by single-family houses
    |> |> >> compared to the area used by commercial/industrial/large residential
    |> |> >> (high rise), I'd have to guess that more than 50% of the total number
    |> |> >> of poles that have any transformers carry one single-phase
    |> |> >> transformer.
    |> |>
    |> |> >Your *guess* is wrong.
    |> |>
    |> |> Not where I live now, nor where I've lived for decades. Again, where do
    |> |> you live that has 3-phase on the pole outside every house?
    |> |
    |> | Everywhere I've lived (some underground).
    |>
    |> You manage to only live in strange places.
    |
    | Nope, Midwest, Northeast/New England, but I see it everywhere.

    I've lived in some of these areas plus the south. I've never seen any kind
    of three phase service besides wye (either 208Y/120 or 480Y/277 and in one
    case 600Y/347) and delta (presumably 240D/120 since there was a center
    tapped leg on the few I've seen) for three phase and split phase (240/120)
    for single phase. I've also seen some 2-wire single phase feeding some
    highway lighting, but I did not know the voltage (could be any of 120, 240,
    277, 347, 480, 600 as far as I know).

    You're sure none of these are in any abundance where you live?
     
  14. Guest

    | In article <fpkv81$ate$>, says...
    |>
    |> >> Currently, the area around Vancouver BC. Other residential areas with
    |> >> single-phase service: near Waterloo, Toronto, and St. Catharines
    |> >> Ontario, near Montreal Quebec.
    |>
    |> >> Where do you live that has full three-phase MV on top of every pole on
    |> >> every street in a residential area? And three transformers on every
    |> >> pole that has a transformer?
    |>
    |> >The transformers aren't on every pole (every third), but the wires
    |> >are. I see it all over. All you have to do is look.
    |>
    |> I *have* looked where I live. I've told you what I see (a single MV
    |> wire on the top of the vast majority of poles in residential areas).
    |
    | Afghanistan?

    If I ever get there, I'll tell you what I see, if I make it back. But
    I have read some descriptions that would suggest something like 380Y/220
    for three phase.


    |> The next level up the distribution hierarchy is 3-phase, so 3-phase
    |> lines do pass through residential areas, but only one phase is tapped
    |> for the line of poles down each street or alley.
    |>
    |> Again, where do you see 3-phase on every pole?
    |
    | Illinois, New York, Vermont (haven't looked here in OH).

    Maybe you should. You'll find a LOT of 208Y/120, some 480Y/277 (larger
    buildings), and maybe some leftover 240D/120, as well as single phase
    service in 240/120. But do take your camera if you are convinced there
    are some "6 star" services around.


    |> Tell us some places.
    |> Even when there are 3 phases, do the transformers occur in groups of 3?
    |
    | Sure.

    And how many lugs on each are wired up? Does each transformer have the
    same number of MV bushings (whether that be 1 each or 2 each)?


    |> Or do you mostly get one transformer per pole, tapping only one of the
    |> 3-phase MV lines? (That's what I see when there does happen to be
    |> 3-phase distribution).
    |
    | One pig per pole, three wires going between poles, under the MV
    | lines.

    That's single phase 240/120 of the Edison split phase variety. No three
    phase services there.

    Look for cases of THREE transformers, each with the same number of MV
    bushings (either all have 1 or all have 2 each), and at least 3 LV lugs
    connected on all three. If only 2 lugs are connected on all three, then
    you have a wye system, usually 208Y/120 but 480Y/277 is possible (600Y/347
    is very rare except in Canada). If 2 lugs are connected on 2 transformers
    and 3 lugs are connected on one transformer, it is probably 240D/120.

    Other possibilities also exist. Be sure to get a number of photos at many
    different angles to get an unambiguous view of exactly how all the wires
    are connected. If you see one with 3 lugs connected on each of 3 separate
    transformers, where the middle lugs of each are connected together, and
    all the outer lugs, plus the joined middle lugs as one wire, supply 7 wires
    into whatever building is served, then be sure to get a LOT of photos.
     
  15. Guest

    |>Actually this is quite common. Even if three phase distribution goes
    |>through a residential area, the transformers on the poles for homes
    |>along the way are usually just one transformer supplying one phase to
    |>that bunch of homes.
    |
    | Different utilities in different areas have different practices, including
    | the willingness to bring three phase down a street that doesn't need it
    | yet, or will never need it.

    I can't rule that out. And maybe I've seen it, as I have seen many cases
    of three phase MV on a residential street without noting whether it was
    going through to somewhere else or if all three phases were used (such
    as by three separate single phase taps). A few streets in town here have
    two sets of three phase MV. I'm guessing some have special uses (like a
    hospital circuit) or are feeding strictly to further distance circuits.
     
  16. charles

    charles Guest

    yes, very useful. A few years ago, the phase from which our house was
    supplied kept tripping out. I seemed to complain more than others, so the
    house was swapped on to phase 2 (Yellow, White, or whatever).
     
  17. Guest

    | In article <>,
    |> In article <>,
    |> > obviously very different practices on different sides of the pond.
    |> > Virtually all residential distribution over here is 3 phase. The only
    |> > time I've ever spotted single phase is when an isolated property has its
    |> > own transformer.
    |
    |> I just wish I had three-phase into my house.
    |
    | yes, very useful. A few years ago, the phase from which our house was
    | supplied kept tripping out. I seemed to complain more than others, so the
    | house was swapped on to phase 2 (Yellow, White, or whatever).

    And someone else's house got swapped over to the bad phase.
     
  18. krw

    krw Guest

    Phil, try getting a handle on reading comprehension; They're ALREADY
    THERE!
     
  19. krw

    krw Guest

    In a residential neighborhood? Get real!
     
  20. krw

    krw Guest

    They surely wouldn't be called that because it's a stupid idea.
    Never climbed a pole, but all three phases are used for Edison 240V
    service. How may lugs is that?
    Bullshit! The three wires were the three phases. You could see the
    connections on the pigs.
    I'm not in the business of supplying your curiosity.
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-