universal uninterruptible power supply

On Wed, 11 Feb 2009 17:05:19 +1100 Phil Allison wrote: | | | | |> ** 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.

|> 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.

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.

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

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).

-- Sue

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

On Thu, 12 Feb 2009 08:03:47 GMT Palindrome wrote: | snipped-for-privacy@ipal.net wrote: |> On Wed, 11 Feb 2009 09:43:58 GMT Palindrome wrote: |> | snipped-for-privacy@ipal.net wrote: |> |> On Sat, 07 Feb 2009 08:50:26 GMT Palindrome 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?

| :-/, *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.

** FUCK OFF

YOU ASININE RADIO HAM IMBECILE !!!

..... Phi l

** FUCK OFF

YOU ASININE RADIO HAM IMBECILE !!!

..... Phi l

** FUCK OFF

YOU ASININE RADIO HAM IMBECILE !!!

..... Phil

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.

-- Sue

| snipped-for-privacy@ipal.net wrote: | |> 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:

1. Two wire 100..120 V grounded at wire A.
2. 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).

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...

-- Sue

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.

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.

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.