| snipped-for-privacy@ipal.net wrote: |> |> In alt.engineering.electrical Michael A. Terrell wrote: |> | |> | snipped-for-privacy@ipal.net wrote: |> |>
|> |> In alt.engineering.electrical Michael A. Terrell wrote: |> |> | |> |> | You are so stupid that you hav enver hear of "Thinking outside the |> |> | box"? |> |>
|> |> You are quite creative. You have that going for you. |> |>
|> |> I know about "Thinking outside the box". But you didn't specify that |> |> box as the one you were referring to before I asked you to. |> | |> | |> | Lame excuse. |> |> Factually accurate. Look back at what you posted (and did not include |> in your last post ... how convenient). It could have been any box. | | | Bull shit.
The creativity, again.
|> |> | No, I SAID THAT I WOULD USE A BATTERY BANK 50% MORE THEN THE MINIMUM |> |> | TO EXTEND ITS LIFE. |> |>
|> |> With some UPSes you can do that. With others, you can't. |> | |> | |> | We were talking a new design so that is a lame answer. Do I have do |> | define 'Lame' as well? |> |> Maybe a new design. But I never said I designed it. I never even gave |> a design. Yet you acted as if I have provided a design. | | | No, I didn't. In fact, you can't even write a decent set of | specifications. That is the whole point. You post stupid ideas, with | no groundwork.
You said I designed it wrong. That is the same as you saying I designed it.
|> Existing designs can be used if full power conversion is acceptable over |> the full voltage range, either 100 to 240 volts for a 240 volt system, |> or 50 to 120 volts for a 120 volt system. Power supplies (chargers, AC |> to DC converters, by any other name) are already designed with this wide |> of an input voltage range. The only change in design that might be |> needed is model specifics, such as a particular capacity or form factor. |> This is stuff electrical engineers frequently do, as evidenced by the |> myriad of products like this on the market. | | | The wide range units switch the input configuration, depending on the | input voltage and under the control of a custom IC. It isn't a single | wide range.
Actually, it is a single wide range. This was verified directly with one of the manufacturers that offered both full range and switched range models. One thing they said is that extra cost of full range is so low, now, that it is reaching the savings of having fewer models. There is some threshold switching that takes place in many models to change characteristics to make it more optimal at different parts of the range. For one model I asked about, that change happens at 166 volts RMS.
|> Where a theoretical design change would be needed is when it is desired |> to have an upper limit on the current being drawn. At lower voltages |> this would mean less power is drawn. | | | You have that backwards. The switching supply is designed to output a | fixed voltage, and the lower the input voltage, the higher the input | current. Also, it may be higher than expected, due to a distorted | waveform at the AC input. It will attempt to provide the power required | by the load, as the input current goes up. That is the major flaw in | your half assed concept.
Again with the inability to read.
I previously in that same post described the normal case of a lower input voltage having a higher input current. Then I described here the special case of a current limit. Do you even understand what a current limit is? Maybe not.
When the current input is limited, and has reached the limit, then the power input goes down as the voltage goes down. Common power supplies just shut down at this point. As I said, this case is a "theoretical design change". But I guess you didn't read those words or even understand what they meant.
|> That would be needed, for example, |> when a nominal power of 1000 watts is working on a 120 volt circuit, and |> it is desired to limit the current at 12 amps to operate within the 80% |> single dedicated device rating on a 15 amp circuit. Down to 83.333 |> volts, the full power can be sustained. Below that voltage, the power |> level must be reduced to stay within the 12 amp limit. So at 50 volts, |> the power would be only 600 watts. If the load being powered is 1000 |> watts, then 400 watts has to come from the battery. But that's only 40% |> of what the battery could carry. If the load being powered is only 600 |> watts, then the battery has no load at all. |>
|> The above figured are based on a hypothetical 100% efficiency ONLY for |> the purpose of simplified explanation. In reality efficiency levels |> would vary around 90% to 96%. It would complicate the explanation to |> use those figures, and make it harder for some people to see what is |> going on. In a real product design case, it would be more complicated. |> That's the job of the engineer doing the actual design. | | | the losses also depend on operating temperature, battery condition, | and the percentage the load represents of the UPS design allows. The | harder you push it, the hotter it runs, and the higher the losses.
I didn't intend to list everything. Thank you for adding to the list so others who read this have a more complete list.
|> |> I *AM* talking about a redesign (without yet doing that redesign) of the |> |> charging (AC to DC) component of the UPS so that it will get whatever |> |> power it can get from a deep brownout condition, and use that to charge |> |> the battery or supplement the use of the battery. |> |>
|> |> It is PLAUSIBLE to do this because switch mode power supplies, which are |> |> devices that convert AC to DC at one or more DC output voltages, can |> |> readily and easily be made to operate over a voltage range greater than |> |> 2:1. Most computer power supplies now do 100 to 240 volts AC continuous, |> |> without needing one of those "115/230" switches. Almost all my wall |> |> warts do this, too. If it can be done for 100 to 240, it could also be |> |> done for 50 to 120, and thus be within the range for the class of deep |> |> brownout I have seen about half the time. Or a 240 volt class UPS can |> |> be left at the 100 to 240 volt range. What will need to be done to |> |> accomodate this is to be sure the current at the low voltage can be |> |> handled, or be restricted/limited. |> |>
|> |> So really, I don't even need to design this. It has already been done. |> | |> | |> | Really? Then go buy it. |> |> I already have many such power supplies. What is not available is such |> a power supply in an integrated UPS. | | | Then it doesn't exist, and you lied.
The wide range power supplies do exist. So no new design is needed for the simple case of operating at 60 volts on a 120 volt system, other than scaling it down from 100-240 to 50-120, which would not be hard. The slightly harder design, which I am sure any experienced power supply designer can do, is the current limiting design. But you don't even understand what current limiting is, so you are way way out of the running for being able to design such a thing.
|> |> | Tell me, Phil, how low of a line voltage do you expect your fantasy |> |> | UPS to work, without being completely on batteries? |> |>
|> |> At least one existing UPS can go down to 86 volts or lower for a 120 volt |> |> system. Switch mode power supplies are readily available for the 100 to |> |> 240 volt range (check your own computer(s) and see). Just build one big |> |> enough to drive the inverter and charge the battery. Front end it with a |> |> 120 volt to 240 volt transformer if you want to power it on 120 volts. Or |> |> just connect it to a 240 volt circuit. |> |>
|> |> If a switch mode power supply can be made to operate over a 100 to 240 volt |> |> range, then a similar design for a smaller voltage could do 50 to 120 volts |> |> if that is the desired system voltage. |> |>
|> |> Note that the 100 to 240 volt range is nominal. They do have a wider range |> |> to accomodate voltage variations of 5% or even 10%. Power supply specs I |> |> have seen often say they work down to 90 volts. And this is without looking |> |> for wider range ones. I bet a real electrical engineer would know how to |> |> make one handle 45 to 305 volts input AC with a reasonbly constant DC output |> |> at some voltage. |> | |> | |> | Is this fantasy supply for a single computer, or for a room full of |> | servers? It makes a huge difference. |> |> It will make a difference when one is being selected for deployment. |> While the concept would work across a wide capacity range, it would only |> be economical for a smaller scale. I estimate the practical limit would |> be around the 6kVA to 10kVA per room or building. | | | | Really? Do you have any ideas what is required to build that | abomination? I do know, and you won't like the answers.
You've shown you don't even understand many of the concepts. How could you possibly be able to design these things if you don't even understand what it is supposed to do? Yeah, I won't like the answer that you can't accomplish it, if I were in the business of making UPSes. I'd have to hire a different engineer.
| Show us you know what you claim by describing what has to be done to | make it operate the way you want, or admit that you are the moron you're | know to be.
I've already described what it needs to do. It needs to keep supplying DC power in such a way that the inverter fully operates at up to the rated inverter load, using all the DC power available from the converter, and gets else is needed (but no more than this) from the battery. I'm not talking about the circuit details. Those things have already been done in other things besides UPSes. This is just a product design (that's not the same as circuit design) and integration issue.