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280V motor on 230V circuit

Discussion in 'Electronic Repair' started by Deodiaus, Apr 26, 2008.

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  1. charles

    charles Guest

    Yes. - but where is it grounded. Formerly it was grounded only at the
    star (centre) point of the local transformer, but more recently is it being
    grounded (again) at the domestic intake point.
     
  2. Yes, although we have 3 types of supply arrangement for earthing
    used on public supplies. (Note that on 240V, there's often far
    more distance between the consumer and the transformer than
    you'll find in the US on 120V supplies.)

    TN-S:
    Neutral is grounded only at the transformer, but a separate
    earth conductor is carried in the supply network and brought
    into the home from that same grounding point.

    TN-C-S (also known as Protective Multiple Earthing):
    A single PEN (Protective Earth and Neutral) conductor from
    the transformer serves as both neutral and ground connection
    in the supply network. The PEN conductor must also be earthed
    regularly throughout the supply network, and it requires very
    high integrity connections to ensure the risk of it breaking
    is very low (this is a legal requirement). Once the supply
    reaches the consumer, the PEN conductor is split into separate
    neutral and earth conductors in the installation.

    TT:
    The supplier grounds the neutral as for TN-S, but doesn't
    provide the consumer with any earthing connection. The
    consumer needs to make their own ground connection for earthing
    (and shouldn't cross-connect this to the neutral).
    TT is only found on old rural overhead supply networks, and
    they are upgraded to TN-C-S when due for refurbishment.

    Even if the supplier does provide an earth connection (TN-S
    or TN-C-S), the installation can choose to ignore it and be
    wired as a TT system. This is sometimes done for submains
    to outbuildings and outdoor electrics, even when the main
    installation is TN-S or TN-C-S.

    These earthing system arrangements are covered in the uk.d-i-y
    FAQ: http://www.diyfaq.org.uk/electrical/electrical.html#system
     
  3. Arfa Daily

    Arfa Daily Guest

    One common neutral that is grounded back at the nearest transformer
    substation, and three phases, fed singly to homes in a reasonably 'balanced'
    way (loading-wise). So one side of the street may be fed from one phase, and
    the other side of the street from a different phase, then further up the
    street, some more houses connected to the remaining phase and so on. Each
    house also has a protective ground connection. Generally, no 'pole pigs'
    except in rural areas. For the most part, each collection of several hundred
    houses, are connected underground to a small building containing 3 phase
    transformers. I think that the input to these stations is around 11kV, also
    underground. The 'hot' side of the supply is usually known as "live" in the
    UK, but is sometimes also known as "phase".

    I'm not an electrical engineer, but that's pretty much the basis of the UK
    domestic distribution system. Commercial premises usually have a full three
    phase plus neutral connection to the network.

    Arfa
     
  4. Deodiaus

    Deodiaus Guest

    I tried first by replacing the capacitor. I could not pry off the
    pump because it was rusted shut and bolted on well.
    The repair guy said it was a break in the winding. He is rewinding it
    for $170.
    I was thinking of doing it myself but I was told that rewinding it
    manually is tough.

    BTW, I cannot refind the "for sale" motor on the web anymore.
     
  5. Guest

    |
    | |> |
    |> | |> |> In article <>,
    |> |>
    |> |> wrote:
    |> |>
    |> |>> There are two different flavors of 220/230/240 volts. Some places
    |> |>> have a
    |> |>> simple system with one wire hot and one wire grounded. Other
    |> |>> places have
    |> |>> a split system where the voltage is split in half to get
    |> |>> 110/115/120 volts
    |> |>> relative to ground, by adding a additional "middle" conductor that
    |> |>> is the
    |> |>> grounded one.
    |> |>
    |> |> Sonny, you need to LEARN the difference between Ground and
    |> |> Neutral......
    |> |> before you spout any further BS.......
    |> |
    |> | What he wrote looks reasonable to me in terms of ground and neutral.
    |> | Neutral is the grounded conductor where I live. He does not say to
    |> | use a ground as a neutral, if that's what you're getting at. I can
    |> | only guess that that may be what you're getting at, you haven't really
    |> | said.
    |>
    |> He might be one of those "knows just enough to be really dangerous" people
    |> on the net. I didn't even mention "neutral". My intent was to explain it
    |> in a simpler way for someone to just understand the basic difference. The
    |> term "middle" was to convey a little more information than "neutral" would
    | <SNIP>
    |
    | Well, I understood what he meant, but maybe I took it the wrong way. When he
    | said middle conudctor I was thinking the center lug on the transformer which
    | is grounded and used as the neutral.

    That is what I meant when I said middle conductor. I intentionally avoided
    calling it neutral for the person I was responding to. I did quote it to
    make it clear (but this apparently was not clear enough for at least one
    person) for others that I was using some other term.
     
  6. Guest

    | Yes, although we have 3 types of supply arrangement for earthing
    | used on public supplies. (Note that on 240V, there's often far
    | more distance between the consumer and the transformer than
    | you'll find in the US on 120V supplies.)

    Our supplies to homes are also 240V. We just ground it in a different
    way through the use of a center tap and an additional wire, which gets
    the neutral designation. For an equivalent _balanced_ load in the US,
    we should see no more voltage drop than in the UK. And that voltage
    drop will be effectively halved between one of the hots and the neutral.


    | TN-S:
    | Neutral is grounded only at the transformer, but a separate
    | earth conductor is carried in the supply network and brought
    | into the home from that same grounding point.
    |
    | TN-C-S (also known as Protective Multiple Earthing):
    | A single PEN (Protective Earth and Neutral) conductor from
    | the transformer serves as both neutral and ground connection
    | in the supply network. The PEN conductor must also be earthed
    | regularly throughout the supply network, and it requires very
    | high integrity connections to ensure the risk of it breaking
    | is very low (this is a legal requirement). Once the supply
    | reaches the consumer, the PEN conductor is split into separate
    | neutral and earth conductors in the installation.
    |
    | TT:
    | The supplier grounds the neutral as for TN-S, but doesn't
    | provide the consumer with any earthing connection. The
    | consumer needs to make their own ground connection for earthing
    | (and shouldn't cross-connect this to the neutral).
    | TT is only found on old rural overhead supply networks, and
    | they are upgraded to TN-C-S when due for refurbishment.
    |
    | Even if the supplier does provide an earth connection (TN-S
    | or TN-C-S), the installation can choose to ignore it and be
    | wired as a TT system. This is sometimes done for submains
    | to outbuildings and outdoor electrics, even when the main
    | installation is TN-S or TN-C-S.
    |
    | These earthing system arrangements are covered in the uk.d-i-y
    | FAQ: http://www.diyfaq.org.uk/electrical/electrical.html#system

    Nice info!

    I'm curious about this: is it legal in the UK for a home to feed their supply
    into their own transformer and ground the secondary at that point as a new
    system?
     
  7. James Sweet

    James Sweet Guest

    No, that's not true. It's 240V, the transformer has a grounded center tap so
    120 from either side to neutral, and 240 between the hots. You find 208V in
    commercial buildings and some apartment complexes that are fed with 3 phase,
    but not in a house, unless you're one of the few lucky people to have 3
    phase available.

    It's clearly a typo and should be 208V.
     
  8. Arfa Daily

    Arfa Daily Guest

    If it's not a silly question, with the motor in question being offered "on
    the web, really cheap", then if it's e-bay, why not use the 'ask the seller
    a question' option, or if it's a reseller, use his on-site 'contact us'
    facility ? Then there would be no debate about typos and exotic voltage
    issues ... :)

    Arfa
     
  9. Benj

    Benj Guest

    This is standard with "pool stuff" around water.
    He is right, it is.
    Here's the first lesson in "shopping like a woman": Ya snooze, Ya
    loose!
    You see that "good price" you MUST buy it right then and there. If you
    futz around trying to make up your mind, it'll always be too late!
    Later it will be gone. [Hey, you think there's nobody else out there
    who can spot a bargain like you?]
     
  10. Guest

    | If you are in North America, and have 120 VAC to the outlets, what you
    | call 220 or 230 VAC in your home is actually 208 VAC, unless you
    | installed some kind of transformer to compensate.

    That's only true if the source transformer is a three phase WYE/star type.
    If you have center tapped delta three phase, or single phase Edison split,
    then you have genuine 240 volts (although with that delta you may also have
    a third wire that is 208 volts relative to ground/neutral).


    | I somehow think that the vendor of the motor made an error. Having 280
    | VAC sounds to me very unconventional, unless this was some kind of
    | special installation.

    It may be a reference to working on 277 volts, which is an available voltage
    in some large commercial/industrial locations.
     
  11. z

    z Guest

    yeah, where do you find 280 volts? it's either 208 or 230.
     
  12. Yes-it could be toast in a couple of seconds. While motors with brushes,
    like the ones used in short duty appliances, like drills and blenters, will
    rotate slower in lower voltages, without problems, Asynchronous motors
    (brushless) will really smoke to death if used in voltages significantly
    lower than nominal. Can't you find a generic pool motor, if you know the
    horsepower, voltage (3 phase? line to line) and intake and outlet gauge? and
    maybe rpm?

    HTH,
     
  13. Nope. LV (low voltage)230-V in Europe is just sufficient for 1 km distance.
    MV (medium voltage) 20 kV for 60 km. HV (high voltage) 150 kV for 220 km.
    EHV 400kV for 500 km with stability issues. 110 volt is so low you need a
    transformer outside each building....
     
  14. James Sweet

    James Sweet Guest


    Learn the system before you criticize it.

    It's not 110V, it's 240V, we simply split it with a grounded center tap
    which gives 120V between each side and neutral, or 240V between the sides..
    There's no transformer per house, except rural applications. Generally 5-10
    houses are on each transformer, sometimes more. The problem with long runs
    is that the voltage fluctuates substantially with large loads such as
    central air conditioning. Standard North American residential service is 200
    Amps 240V, I gather this is quite a bit larger than typical European
    domestic stuff, so stretching it over 1km distance would require
    prohibitively large cables or suffer from wide voltage swings. Makes more
    sense to run 7200V down the street and locate a smallish transformer near
    every half dozen houses.
     
  15. I'm perfectly aware of this, only in theory, though, as I've never been in
    USA. I have worked, though in the decommisioned US base in Gournes, really
    impressive your distribution systems:)
    And in Europe we have 400 V (3 phase) line to line voltage. It's 230 line to
    earth. Large motors and conditioners use 3 phase. Normal residence is 40 A
    230 V single phase, or for energy hogs 400 V 3 X 40 A 3 phase..
     
  16. Europe.

    I also noticed just last week that Malaysia and Singapore use 230V (@50Hz).
     
  17. Residential power in Sweden is 400V 3 phase, main fuses normally 25A
    or lower.

    Room outlets are wired with one phase, neutral and ground to get 230V.

    There is a smallish transformer station in the neighborhood which
    probably powers two entire blocks. I would guess somewhere around 20-30
    houses.
     
  18. Absolutely the same here, in Greece we are using only Schuko sockets, from
    german Schutzkontakt, security contact. There is a larger substation, maybe
    2-3 for a city (in Iraklion we have 3, 180,000 residents) that steps down
    from the transmission voltage, 150 kV down to primary distribution voltage,
    15 kV that is the distributed with cables buried in earth. Our local power
    station has units with 15 kV (older) and newer with 6.6 kV alternators, all
    is stepped up to 150 kV even for the ~15 km to Iraklion. In capitals, like
    Athens, electricity comes at 400 kV, is stepped down to 150 kV for secondary
    transmission, again goes to the areas af the city with underground cables,
    stepped down to 15 kV locally, and then distributed again (the main
    generation facilities are in Kozani, West Macedonia, and they burn brown
    coal. Typical size of a unit is 300 MW, voltage 21 kV and current 10 kA
    which is stepped up to 400 kV, 400 A line current for transmission to Athens
    and Thessaloniki).
     
  19. Similar in UK.

    In most European countries, there's a single phase current limit,
    above which you have to take a 3-phase supply. In the UK, that's
    100A, so it's not very common to have a 3-phase supply although
    you can ask for one if you want a 3-phase supply. In some other
    European countries, the single phase limit is as low as 20A, so
    just about everyone has a 3-phase supply.

    Residential substation transformers (11kV down to 230/400) are
    usually 1MVA, feeding a number of streets. A substation may have
    more than one transformer in some cases (although they usually
    only start out with one). Obviously, smaller transformers are
    used where there aren't so many houses, and these are sometimes
    pole mounted if the wiring is overhead.
     
  20. It's the regulation at 120V which people notice.
    If you want to call it a 240V supply, then you
    need to call EU supplies 400V or 415V. That's
    equally misleading.
    The transformers are small in comparison, which gives poor
    regulation in comparison (and as I said before, it's the
    regulation at 120V which is the primary concern -- regulation
    of 240V across 2 hots doesn't matter much for typical US 240V
    loads).
     
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