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universal uninterruptible power supply

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

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  1. Guest

    | I never said the transformer had to be 50/60. Take the line, rectify it,
    | then invert it at high frequency and drive the primary of a *small*
    | transformer. Take the secondary, rectify it and drive a power inverter at
    | 50/60. Complete isolation and no 'big transformer'.

    What is the efficiency of all this conversion to and from a higher frequency?


    |> So how can you produce a "grounded center tap" system with a "single,
    |> larger" inverter?
    |
    | Ah, for that you *would* use a large 50/60 transformer as the output stage.
    | Drive at 240 and have center-tapped secondary. At least that's one way.
    | There may be others.

    An "other" way I have in mind is a pair of synchronized 100-120 V inverters
    wired in series. Ground would be connected to the center when/where that
    kind of system is needed or desired.


    | So that would be a compromise of either a big bulky 50/60 transformer or
    | more-difficult/ less-reliable inverter design.

    Are 100-120 V inverters less reliable? For a given UPS capacity this would
    involve 2 inverters at half the capacity, of course.


    |> If the derived system is _not_ a "grounded center tap" type system,
    |> then that
    |> would complicate the bypass switching, because that would mean a
    |> sudden shift
    |> in grounding relations when the bypass is engaged.
    |
    | If the service is for a grounded center tap, then simply ground the center
    | of the inverter output (either center-tap of power 50/60 transformer or leg
    | between your two-inverter design). With *just* a ground connection on the
    | secondary side, there isn't any interaction with the mains.
    |
    | Obviously if the unit is to be used in a variety of service, the exact
    | grounding of the output has to be user configurable. But if the output is
    | isolated from input using either a high-frequency or low-frequency
    | transformer, you can ground any *one* point of the output with no
    | ill-effects.
    |
    | (well, grounding one side of a power inverter so it 'looks' like a
    | grounded-on-one-side UK supply, *may* cause some noise issues and EMI that
    | affects other equipment, but the basic inverter would still be operational).

    The goal I'm looking at is a UPS that can be connected to either kind of power
    system. In the case of single ended, either end might be grounded (so it can
    be used in continental Europe and similar places with reversable plugs). In
    the case of center tap grounded, only the 2 hot wires are coming in, and the
    neutral is not (pure 240V American style). The output should match the input
    system, and it should be automatically done correctly and safely. That means
    the grounding conductor would be connected at the appropriate point on the
    output. In the case of American center tapped 240V, the point between the
    two inverters would be grounded, but no neutral grounded conductor would be
    needed since the intent is to provide 240V (200V in Japan) the same way it is
    available from the supply. In the case of single ended, the correct output
    conductor has to be grounded such that when the bypass switch is engaged, the
    grounding status does not change. There should be NO "ground shift". That
    would mean opening the grounding conductor and closing the neutral conductor
    at the same time. But should this be an open transition to ensure there is
    no issue with "downstream double bonding"?
     
  2. Guest

    |
    |
    | <>
    |
    |> ** Then yours is STILL an utterly silly question.
    |>
    |> For Christ's sake - TELL US what YOU think the safety problem is
    |> ??
    |>
    |>
    |> The safety problems would depend on the specific design. If relays that
    |> can,
    |> under conditions of failure (e.g. one of them might not make the switch
    |> for
    |> reasons that might include an open coil) result in an unsafe condition
    |> (such
    |> as exposing operators to dangerous voltage, or create a fault condition),
    |> then
    |> it could be (should be) considered unsafe by listing agencies. That can
    |> be
    |> mitigated by making the design use "double throw" relays that just cannot
    |> be
    |> in both states at once (though could be in an in between state).
    |
    |
    | ** Yaaaaawnnnnnnn - more ABSURD gobbledegook......



    |
    |
    |> One design idea was to have 2 inverter sections in series, with each of
    |> the
    |> 3 connections having a relay that could connect that section to ground.
    |
    |
    | ** You clearly have no clue of the difference between supply neutral and
    | safety ground.
    |
    | Go away - IMBECILE.

    Normally I don't call people names. But in this case, you are earning it.


    |> I sure do.
    |
    |
    | ** No you do not.
    |
    | Cos you keep referring to neutral as "ground".

    Get your clue now;

    Not all electrical systems have a neutral by its exact definition. A
    neutral conductor carries the imbalance current from 2 or more current
    carrying conductors. In a 2 wire system, there is no actual neutral
    since there is no imbalance. Where a 2 wire branch circuit is connected
    to a multi-wire system, one of the wires is usually (but not always)
    connected to that system's neutral. That wire often gets referred to as
    the neutral. The referral is conventional and the meaning is understood
    but by the definition it is not correct. The correct term is "groundED
    conductor".

    There is a separate groundING conductor. In the case of a separately
    derived system, a groundED conductor (whether it is a neutral or not)
    is derived by bonding it to the groundING conductor.

    A UPS with a bypass poses an interesting challenge. When it switched
    to bypass mode, it cannot be a separately derived system. The groundED
    conductor is pass through as a groundED conductor. The groundING
    conductor is not to be connected to any current carrying conductor in
    this case.

    When the UPS is NOT switched to bypass mode, there are two ways it can
    be operating. One way is as a separately derived system. This is like
    an isolation transformer. The groundING conductor is connected to the
    conductor intended to be grounded, or in the case of an American style
    240V circuit, the groundING conductor is connected to the point between
    two 120V isolated sources, whether or not that point is carried out as
    a neutral conductor, or not. For single ended 240V systems like that
    used in Australia, the groundING conductor is connected to the proper
    output conductor. For reversable single ended 240V systems like that
    used in Germany, the groundING conductor is connected to whichever
    output conductor is serving as the groundED conductor (which MAY be
    changed as a result of reversing the groundED relationship of the source
    supply).

    The UPS could also be operated in a mode like an autotransformer. This
    mode would require (at least by American safety standards) the groundED
    conductor be supplied and passed through, and all other conductors be
    related to it.

    The UPS could also be operated floating.

    Whether the latter two operating modes are legal, or could practically
    be made legal, under various safety codes, is a big issue. I believe
    in limited cases this can be done under American electrical codes. But
    such setups would be more complex and probably preclude universal use
    on non-American systems.


    | AC supply conductors are NOT and CANNOT be linked to "ground" inside any
    | appliance.

    Read above.

    I suggest you do some googling for "seperately derived system" and also for
    "autotransformer" (or "auto transformer" or "auto-transformer" as the term
    is often spelled that way in many places). Then do some learning on how the
    groundING and groundED conductors can be used. Pay particular attention to
    how the groundING and groundED conductors must be kept separate from each
    other.


    | FUCKWIT !!

    Then you need to find the nearest mental health services clinic and make an
    appointment to seek some care for your attitude and anti-social problems.
     
  3. Guest

    |> 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 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 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.
     
  4. Phil Allison

    Phil Allison Guest

    <


    ** Phil - YOU are nothing short of a

    TOTAL FUCKING PSYCHOPATH !!!

    & FUCKWIT RADIO HAM !!!!!




    ** Not once and nowhere have YOU stated what you are talking about.

    Is you imaginary universal UPS a " plug in" appliance or not ??


    ** What totally INSANE SHIT !!

    A neutral is a current carrying conductor that is tied to ground potential.



    ** Over and over again - you FAIL to STATE what the damn safety issue
    is.

    S T A T E I T NOW FOR GOD'S SAKE !!
    -----------------------------------------------------------

    DO NOT KEEP ALLUDING TO SOME UN-STATED PROBLEM !!!!
    ---------------------------------------------------------------------------------


    I bet you cannot ,

    cos you are BULLSHITTING like CRAZY.



    ....... Phil
     
  5. Phil Allison

    Phil Allison Guest

    <>

    Phil Howard KA9WGN is a RABID NUTTER
    ** More INSANE SHITE !!!!


    ** Still that does not make them " opposing phase "

    The criticism was about CORRECT TERMINOLOGY

    YOU FUCKWIT DAMN

    RADIO HAM

    MORON !!!!!!!!






    ....... Phil
     
  6. krw

    krw Guest

    I know enough to know that you're a clueless twat!
    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?
    Yes, I deny that two wires can be 120 degrees apart. It is
    IMPOSSIBLE, you stupid twit! Draw the bloody phase diagram.
     
  7. Palindrome

    Palindrome Guest

    This is a UPS that we are discussing - at some point the input has to be
    converted to DC and the output stages powered by DC. As the
    proliferation of SMPSU shows, the 50/60Hz transformer has near enough
    disappeared for the former. The same design arguments apply to the
    latter = there are considerable advantages in stepping the battery
    voltage up to a high enough DC voltage, using a 20kHZ inverter (with
    20kHz transformer) and follow it with a transformerless 50/60Hz output
    stage - than have a 50/60Hz inverter (with 50/60 HZ transformer).
     
  8. daestrom

    daestrom Guest

    No, 120V inverters are not inherently less reliable. But two of any thing
    instead of one means twice as many components to fail. Adding a second
    inverter probably reduces the overall products reliability by more than
    adding a transformer to a single inverter.

    :-/, *automatically* reconfiguraing the ground sounds like trouble. That
    implies some switching/relaying in the ground path and I doubt that would
    fly past codes.

    And how can the unit sense what the input configuration is? Unless you
    supply it with a separate ground for sensing what (if any) input phase is
    grounded, I don't see how it can tell.

    It would probably be easier to leave the grounding to a 'user configurable'
    setting. Have the user configure the output inverter ground connection
    before installing the unit and leave it connected all the time. Then when
    you switch from bypass to UPS output, there is no ground-shifting either.

    daestrom
     
  9. daestrom

    daestrom Guest

    No Phil, you are out-to-lunch. His definitions of groundED and groundING
    conductors is right out of the NEC. Multiwire systems have a 'neutral'
    whether or not it is gourndED or not.
    It is obvious to people that understand 'separately derived systems', that
    the issue is keeping the same output conductor groundED in UPS mode as in
    bypass mode. When the UPS is operating in bypass mode, you have the output
    conductors connected to the input conductors and whichever one of those that
    is grounded is obviously carried through to the output. When the unit
    switches from bypass to UPS mode, the output stage of the UPS needs to
    replicate which conductor (if any) is groundED.

    Since different parts of the world connect different conductors to ground,
    he wants to have the UPS output sense which (if any) of the supplies
    conductors is grounded and configure this UPS output the same way so when it
    shifts from bypass mode to UPS mode, the load doesn't have a shift in which
    of the supply conductors is grounded.

    Maybe you need to read up on separately derived systems.

    daestrom
     
  10. Phil Allison

    Phil Allison Guest

    "daestrom"

    ** No I am not - but YOU are.


    ** What he wrote at the top of this post ( A neutral conductor.... ) was
    TOTALLY INSANE.

    PLUS he asked about ANY country on the planet.


    ** Got nothing to do with the wiring of an APPLIANCE !!

    Cos in ANY of them, neutral and active are treated just the same cos either
    or both can be "hot" under certain conditions.



    ** Where is the FUCKING safety issue ??

    Current carrying conductors are NOT contactable by users.

    ** No such need exists at all.

    That is the BIG FALLACY.


    ** The one connected to ground potential is called NEUTRAL.

    The other one is called ACTIVE.

    Maybe there are two actives and no neutral sometimes - ie balanced power.


    ** Thing is, it never matters and there is ZERO safety issue.

    Go **** yourself.



    ...... Phil
     
  11. Guest

    | wrote:
    |> | wrote:
    |> |>
    |> |> | A transformer operating at a frequency rather higher than mains is
    |> |> | pretty cheap, small and efficient and, IME, very reliable..
    |> |>
    |> |> Of course a higher frequency means a smaller transformer. But then, you
    |> |> don't have 50/60 Hz output from that transformer.
    |> |
    |> | For a 20kHz transformer, its output is going to be converted to
    |> | (typically several hundred volts) DC and then fed to an output stage
    |> | that generates the 50/60Hz required.
    |>
    |> So how many total stages are involved with all this, and how much power loss
    |> is involved as a result? You have to convert the power to 20 kHz first just
    |> to use that lightweight transformer. Then you have to convert it back to
    |> ultimately 50/60 Hz again. It would seem to me that all that conversion would
    |> make the reduced transformer loss meaningless.
    |
    | This is a UPS that we are discussing - at some point the input has to be
    | converted to DC and the output stages powered by DC. As the
    | proliferation of SMPSU shows, the 50/60Hz transformer has near enough
    | disappeared for the former. The same design arguments apply to the
    | latter = there are considerable advantages in stepping the battery
    | voltage up to a high enough DC voltage, using a 20kHZ inverter (with
    | 20kHz transformer) and follow it with a transformerless 50/60Hz output
    | stage - than have a 50/60Hz inverter (with 50/60 HZ transformer).

    So: AC -> DC -> 20 kHz AC -> step-up -> high V 20 kHz AC -> high V DC ->
    50/60 Hz AC
    Is that right?
     
  12. Guest

    | :-/, *automatically* reconfiguraing the ground sounds like trouble. That
    | implies some switching/relaying in the ground path and I doubt that would
    | fly past codes.

    Listing codes, like UL?


    | And how can the unit sense what the input configuration is? Unless you
    | supply it with a separate ground for sensing what (if any) input phase is
    | grounded, I don't see how it can tell.

    There would be an incoming EGC. It should detect how that EGC relates to
    the TWO wires of input. If it fits on or nearly on a point between the 2
    input wires, or within some boundaries allowing for 120 degree phase angles,
    then the ground configuration can be known. If the EGC does not seem to
    relate to the power it gets, it should enter "disabled" operation mode (e.g.
    shutdown to just enough to display a status of the problem).


    | It would probably be easier to leave the grounding to a 'user configurable'
    | setting. Have the user configure the output inverter ground connection
    | before installing the unit and leave it connected all the time. Then when
    | you switch from bypass to UPS output, there is no ground-shifting either.

    Assumes too much from the user. Of course, I'mt not expect 100% idiot proof.
    There will always be radical idiots. It should just be "plug and play" in any
    200V to 240V system world wide.
     
  13. Guest

    | 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.


    |>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.

    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.


    |>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?
     
  14. Phil Allison

    Phil Allison Guest

    <>


    ** **** OFF


    YOU ASININE RADIO HAM IMBECILE !!!






    ...... Phi l
     
  15. Phil Allison

    Phil Allison Guest

    <>


    ** **** OFF

    YOU ASININE RADIO HAM IMBECILE !!!






    ...... Phi l
     
  16. Phil Allison

    Phil Allison Guest

    <>


    ** **** OFF


    YOU ASININE RADIO HAM IMBECILE !!!





    ...... Phil
     
  17. Palindrome

    Palindrome Guest

    Almost. I'd suggest:

    The first bit would be-

    AC -> DC -> 20 kHz AC -> step-DOWN -> Very LOW voltage 20 kHz AC -> Very
    LOW V DC ->

    This produces the very low voltage DC needed to (1) charge/maintain the
    battery voltage and (2) provide power for the output inverter when mains
    is available.

    All the above is, is a SMPSU, not very different to the one in any
    desktop computer.

    The second bit would be-

    Very LOW V DC -> 20 kHz AC -> step-up -> "high" V 20 kHz AC -> "high" V
    DC -> 50/60 HZ AC


    Which is just what you would find in most boats/RVs etc, to provide a
    mains supply from one or more deep-discharge batteries.
     
  18. Guest

    | wrote:
    | <Snip>
    |> So: AC -> DC -> 20 kHz AC -> step-up -> high V 20 kHz AC -> high V DC ->
    |> 50/60 Hz AC
    |> Is that right?
    |>
    |
    | Almost. I'd suggest:
    |
    | The first bit would be-
    |
    | AC -> DC -> 20 kHz AC -> step-DOWN -> Very LOW voltage 20 kHz AC -> Very
    | LOW V DC ->

    How well filtered would the first AC -> DC part need to be? I would think
    it might not matter, much.


    | This produces the very low voltage DC needed to (1) charge/maintain the
    | battery voltage and (2) provide power for the output inverter when mains
    | is available.
    |
    | All the above is, is a SMPSU, not very different to the one in any
    | desktop computer.
    |
    | The second bit would be-
    |
    | Very LOW V DC -> 20 kHz AC -> step-up -> "high" V 20 kHz AC -> "high" V
    | DC -> 50/60 HZ AC
    |
    |
    | Which is just what you would find in most boats/RVs etc, to provide a
    | mains supply from one or more deep-discharge batteries.

    Ultimately this can be encapsulated:

    AC at supply voltage/frequency -> [first bit] -> DC at battery voltage
    Appropriate parallel/switched operation with batter{y,ies}
    DC at battery voltage -> [second bit] -> AC at utlization voltage/frequency

    Now, back to my original issue, with these "encapsulated" modules doing the
    AC (supply) -> DC (battery) -> AC (utilization)

    My concern is the practicality of a universal UPS that works on an AC power
    supply in the 50..60 Hz range, with any one of these systems:

    1. Two wire 200..240 V grounded at wire A.
    2. Two wire 200..240 V grounded half way between wire A and wire B
    3. Two wire 200..240 V grounded at wire B.

    With the _possibility_ that it can also at least supply output power like:

    4. Two wire 100..120 V grounded at wire A.
    5. Two wire 100..120 V grounded at wire B.

    The design with 20 kHz AC step-down and step-up stages doesn't seem to apply
    to dealing with the utiliztion voltage systems here, EXCEPT that it could be
    a semi-split design, where the inverter is a single unit up to the point where
    the final "high" V DC is converted to the final 50/60 Hz AC. If the latter is
    split into two parts, along with that final DC voltage being chosen for this,
    it could still produce TWO isolated 100..120 V AC outputs that could be used
    to produce system #2 above, as well as #4 and #5.

    There are other issues. For example if the UPS has domestic outlets, there
    will be an issue of which conductor is allowed to be grounded. With outlets
    of the style used in Argentina, Britain, France, India, and USA (for 120V,
    not for 240V), a specific conductor must be the grounded one (let's call it
    wire A). If the UPS were to output any other system of power, it would be
    operating in an unsafe way with respect to the expectations in that country.

    However, if a correctly wired AC supply were given, it could "learn" what the
    correct way is and output exactly the same. I don't know if that would enough
    for the appropriate equipment safety listings.

    Consider the case of Argentina and Australia. They use the same outlet/plug
    design, but have the current carrying conductor that is to be grounded in the
    opposite configuration. Consider a UPS constructed with this kind of plug
    and outlet. It could learn which conductor is grounded and do the same for
    its outlet. That's case #1 and #3 above. From an engineering perspective,
    how hard would it be to make it safe under the conditions that someone does
    in fact, actually plug it in to a live outlet in the host country (as opposed
    to plugging it in one, then taking it to the other and operating it standalone
    using its charged battery power, or plugging it into an incorrectly wired
    outlet).
     
  19. Palindrome

    Palindrome Guest

    The main question is whether the savings in cost resulting from only
    having to make (and support) one product would be greater than the
    increased cost of a more complex design - and getting that one design
    through all the approvals process of all the countries concerned. Not
    forgetting the costs resulting from the delay in getting such a product
    to market as a result of all of these approval processes.

    As we appear to be about to enter into a protectionist spiral - now may
    not be a good time to invest in "universal" designs...
     
  20. krw

    krw Guest

    Perhaps form your perspective that's true; you aren't anything
    useful.
    I didn't change your words, idiot.
    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.
    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.
     
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