Connect with us

universal uninterruptible power supply

Discussion in 'Electrical Engineering' started by [email protected], Feb 6, 2009.

Scroll to continue with content
  1. Don Kelly

    Don Kelly Guest

    Phil is quite correct. You are wrong.
    Phil is clearly referring to a 3 wire system which can have voltages
    measured with respect to the neutral' Then the two "hots" can be 180
    degrees apart (120/240), or 120 degrees apart (120/208 or277/480 or...)
    as in practical systems or whatever relationship that one can use (i.e.
    2 legs of any n (n>1) phase star system.

    In the case of a two conductor line, "phase" is meaningless as you have
    only one voltage which is always in phase with itself (not 180 degrees
    apart)- regardless of the assumed polarity (it is meaningful for voltage
    and current). Phase implies a relationship between two quantities.
     
  2. krw

    krw Guest

    No, I am not.
    That may be what he's referring to but that is *NOT* what he said. It
    takes three points to define a plane. A 120 degree angle don't fit on
    a line.

    It takes three points define a plane.
     
  3. Guest

    | On 14 Feb 2009 06:41:17 GMT, wrote:
    |
    |>| On 12 Feb 2009 02:13:59 GMT, wrote:
    |>|
    |>|>
    |>|>|> Source supply is 2 phases taken from a 3 phase system, such as 208Y/120 as
    |>|>|> found in USA and Canada, or 220Y/127 as found in Mexico. In Mexico, it is
    |>|>|> more common to have 120 degree phasing than to have 180 degree phasing.
    |>|>|
    |>|>| The "2 opposing phase line" still have a 180 degree relationship to
    |>|>| each other, moron. Two lines *CANNOT* be 120 degrees from each
    |>|>| other. <sheesh>
    |>|>
    |>|>So you really have THAT narrow of an electrical power engineering experience
    |>|>level? Sheesh. I guess I will have to dismiss *EVERYTHING* you post as from
    |>|>someone who simply does not have much experience in power systems. Maybe you
    |>|>don't even have any.
    |>|
    |>| I know enough to know that you're a clueless twat!
    |>
    |>Whatever you think you know, it isn't enough for anything useful.
    |
    | Perhaps form your perspective that's true; you aren't anything
    | useful.

    What I stated is still correct. Just because YOU can't read it does not
    change anything. There are others who understood what I wrote.


    |>|>I actually have worked with equipment connected to lines that actually are
    |>|>120 degrees apart from each other. Theese were 120 volts relative to ground
    |>|>and had a voltage difference of 208 volts between each other. The NEC even
    |>|>has specific rules for this kind of system (so there are a LOT of other
    |>|>electrical engineers and electricians that have plenty of experience with
    |>|>these kinds of systems). For example NEC 310.15(B)(4)(b) which says that
    |>|>this kind of system requires including the neutral conductor in conductor
    |>|>counts for derating purposes, since it will carry current even when both of
    |>|>the 120 degrees-apart current carrying conductors have equal resistive loads
    |>|>at PF 1.
    |>|
    |>| I repeat, maybe you'll get it one day, TWO wires CANNOT be 120 degrees
    |>| apart with respect to each other. I don't care how many phases were
    |>| generated. Ever hear of 208 single phase?
    |>
    |>So now you change the words to suit your own agenda? Look at my post to see
    |>I'm talking about a TWO phase angle single phase system which is actually a
    |>THREE WIRE system.
    |
    | I didn't change your words, idiot.

    Call it a "change", or not, or call it something else. But it is YOU who came
    up with the notion of "TWO wires" in this thread. Granted that you did insist
    there cannot be a 120 degree phase angle between just two wires. There cannot
    be a 180 degree phase angle, either.

    Maybe you know stuff. But your personal difficulty (which I have seen before a
    few times in this newsgroup) is understanding what you read. Or, maybe you are
    just making stuff up intentionally just so you can have an opportunity to make
    accusations at people. You and a handful of people on the net are like that.


    |>quoted again:
    |>
    |>|>|> Source supply is 2 phases taken from a 3 phase system, such as 208Y/120 as
    |>|>|> found in USA and Canada, or 220Y/127 as found in Mexico. In Mexico, it is
    |>|>|> more common to have 120 degree phasing than to have 180 degree phasing.
    |>
    |>The "2 phases taken from a 3 phase system" is a THREE WIRE system. But this
    |>is something you apparently don't comprehend.
    |
    | Don't lie. You said:
    |
    | "But what about the ability to safely operate in all electrical
    | systems in the world (at the 200-240 volt configuration in
    | countries like USA and Japan that operate on 100-120 volts
    | L-N with 2 opposing phase lines which may be 180 degrees
    | apart, or may be 120 degrees apart).
    |
    | I gave you a chance to correct your insanity which you, like the
    | little girl you are, decided to make worse by attacking.

    There is nothing to be corrected. It is already correct as it stands. But,
    since you have reading comprehension problems, I'll try to explain it for you.

    The reference to "2 opposing phase lines" are the specific wires one may
    connect to in order to get a certain voltage, which in most homes in the
    USA should be a nominal 240 volts. But these are THREE wire systems, or
    in some cases THREE of the total of FOUR wires. The neutral is there.
    It is part of how the system is derived and how it is measured. Just
    because many loads use and work with just 2 of the 3 or 4 wires does not
    mean the system does not have 3 or 4 wires.

    My postings are NOT (usually) intended to be complete beginner tutorials.
    Some assumptions of understanding will be made in order to keep postings as
    succinct as possible to get my point across. If it failed for you then I
    would be sorry about that if you were a beginner seeking to understand new
    stuff, and I would be willing to explain things. But YOU don't seem to fit
    that category. You know enough to be dangerous. I can't do anything about
    that. it's your problem and you are the only one who can fix it.

    I did not start any attack. You (and the "other Phil") did. You've done
    this before in past threads, some with me, and some with others. So I'm not
    surprised.


    |>|>I would suggest you stay away from these kinds of systems. But if you deny
    |>|>they even exist, then I'll have to suggest you stay away from all power systems
    |>|>since your ability to recognize what you are dealing with is in major doubt.
    |>|>You wouldn't know you are dealing with a 120 degree system if you believe it
    |>|>cannot exist. And that makes you a danger around electrical power wiring of
    |>|>those kinds of systems.
    |>|
    |>| Yes, I deny that two wires can be 120 degrees apart. It is
    |>| IMPOSSIBLE, you stupid twit! Draw the bloody phase diagram.
    |>
    |>It's a very REAL system that exists. It's a very REAL system that the NEC
    |>has code written to deal with issues specific to this kind of system. Do you
    |>deny the NEC?
    |
    | Two wires *CANNOT* be 120 degrees apart, you stupid twit! A plane
    | *requires* a third point, idiot. I sure hope you aren't an engineer.

    Again, I never said two wires can be ANY degrees apart. That is entirely in
    your imagination. I referred to 2 phase angles. That *IS* a minimum of a 3
    wire system. I didn't need to explain that in the context of this newsgroup.
    If I were writing in alt.engineering.electrical.students.freshmen, then maybe
    I would be expected to explain that.

    I am a software engineer. I have taken electrical engineering courses as
    high as the senior level (in digital design). I never took power engineering
    courses. But I did understand many of the basics of electrical power as early
    as junior high school. I even worked out the mathematics for polyphase systems
    myself even with the limited level of trigonometry I had at the time. I did
    learn more about power systems, and in particular, electrical codes, over the
    past 25 years, because I was involved in designing data centers where power
    loading, cooling, and related issues had to be figured in. I did take courses
    in audio engineering and signal processing. I know what phase angles mean.
     
  4. Don Kelly

    Don Kelly Guest

    a) If you had read the thread in context, the reference to neutral is
    there.

    b)In the case of two "lines"(as referred to electrically-i.e.
    conductors), - there is only a single voltage between them- You can
    assume a polarity of one "line" with respect to the other but you cannot
    define a phase of the voltage with respect to itself.

    c)This has nothing to do with planes and "lines" in the geometrical sense.

    d)Admittedly the wording could be changed to eliminate the word "line"
    but the usage is common and the meaning is clear.
     
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

-