On Thu, 04 Oct 2007 11:22:19 -0400 kony <spam@spam.com> wrote:
|>Maybe someone could make such a device entirely in a power supply form
|>factor?
|
| I fail to see what purpose that would have, since it's not
| as though we'd have a system without the main power supply
| and very few cases can accomdate two PS2/ATX supplies. I
| suspect we were talking about putting it in one or two 5
| 1/4" bays because that's the only likely available space in
| a typical computer case. Most people don't have more than
| one, maybe two optical drives and most midtower cases have
| at least 3, 5 1/4 bays unless we also consider many of the
| OEM systems which have only two bays, but these typically
| come with only one optical drive so there is still one bay
| available.
Many computers I have seen with dual/redundant PSUs have half
size PSUs. Use that half size design and make a battery box
in the other half. If the port for redundant PSUs can supply
power from one to the other, it might be plausible to make a
battery box that plugs straight in to where redundant PSUs
plug in.
But sure, for other cases, grabbing some unused space in the
drive bays for the battery box would work.
|> It depends on how much time we're asking it to handle. If
|>we want to ride though the 2-4 second power blinks which make up over
|>half of power outage problems, rather small batteries would do, and
|>this might even be doable with capacitors alone.
|
| Yes it would be possible with capacitors, but to have only a
| few seconds of runtime vs several minutes with a typical $30
| UPS, the market for it seems quite small, driving up the
| price even more. If surviving a power outtage, even
| briefly, is important, it's not that much of a problem to
| have a modest sized UPS nearby. It's certainly smaller than
| the system is and we don't see everyone rushing out to be a
| miniMAC just to shave this space. Instead the typical
| owner/user appears to prefer versatility, power, and value
| over small size.
Someone might consider the capacitors, even if more costly than
a cheap UPS, to be a good choice because it fits inside the case.
Some cases these days are made with PSU at the bottom. Maybe
they can just make a case with a full length space at the bottom
for a complete UPS-like integrated power system much like the OP
seems to want.
|>If we want a couple minutes to do a quick clean automatic shutdown,
|>that could be harder, but considering the running time of batteries
|>in a laptop, I think even this is doable in a full sized PSU box.
|
| Given a decent DC-DC regulation circuit on it's output, yes
| it would be possible. However, filling the entire volume of
| a power supply with Li-Ion batteries as used in a laptop
| would be very expensive. That it's a niche product with a
| custom DC-DC power supply adds even more to the cost. IMO,
| the finished product would have to sell for several hundred
| dollars to be profitable enough for the manufacturer to
| continue production.
|
| That seems like a pretty large cost, especially considering
| that if all one really needed was to survive brief power
| outtages, they could just hook a std keyboard, mouse and
| monitor up to a laptop and use that instead. Since it is
| targeted towards, and bought by the masses, it becomes far
| more cost effective.
I agree. A laptop would be a good choice even for someone like me who
has relatively little need for portable computing, just to have something
that can be usable in a long term power outage.
For my servers, my ISP has a big (3 phase) UPS system backed up by a
generator.
For my other computers, I just want them to shut down clean for a long
outage. A common UPS will do. The only issue I have is it would help
to run everything on 240 volts instead of 120 volts (I've reached the
limit of the one dedicated 120 volt circuit that was originally in that
room. Now I either need to add a 2nd one, or find a 240 volt UPS that
can handle the double-hot power system 240 volts in the USA has. There
are some around.
--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / spamtrap-2007-10-04-1315@ipal.net |
|------------------------------------/-------------------------------------|
>| At the currents used these typical silicon bridge
>| rectifiers have about 0.6(n)V drop each... so ok, I rounded
>| up to 0.7V, and it's going through 2 of them so that's
>| 0.6(n)V * 2, I'll round up in your favor to 1.4V drop (out
>| of about 340VDC total).
>|
>| 1.4/340 = 0.4%
>
>Why do you think this is the correct formula?
Why do you think it isn't? 1.4V loss with resultant ~
340VDC immediately following the rectification stage in a
typical passive PFC PSU. In active PFC the voltage would be
a little higher, even less rectification loss. Since the
loss stage directly feeds the following, the current is
constant between the two. voltage loss divided by resultant
voltage.
>
>
>| If you have some specs and math to back up your claim,
>| please share it.
>
>I don't have specs on the rectifiers. Why would I?
Because any sane discussion of loss in a discrete part would
entail referencing the datasheet specs, or at least a
datasheet of same kind of device. In this case we can be
even lazier though and still reach a rough ballpark because
it's a typical moderately high voltage rated silicon diode
bridge as already mentioned.
>But what I do
>have is heat sense. They, and the heat sinks attached, do get very
>hot. Perhaps your measurements are missing some harmonics? I am
>curious why the math doesn't match the reality. I wasn't before as
>I never had a reason to do the math, myself.
Something can feel warm to hot while still having a fairly
low power loss. A TO220 cased part for example will feel
quite hot with only 1W loss, unless heatsinked fairly well
and no bridge rectifier has a very massive 'sink, actually
the 'sink itself can make it seem even hotter because when
you touch it, the metal conducts heat to your finger at
higher rate than the epoxy casing would, though of course it
is offset by that epoxy casing being a bit cooler due to
having the 'sink on it.
Suppose the PSU is using 1A (@340VDC), that 1A * 1.4V =
1.4W, certainly enough to make it feel hot, and yet still a
very small loss in the context of powering a computer.
>
>Maybe if you work out the math for all the other parts in the PSU,
>maybe we can see where the other 99% of the power is lost.
There isn't 100% power lost, if there were there wouldn't be
any output to the system.
>| You're beating a dead horse at this point. If we're talking
>| about solar, it's already a DC battery array so there was no
>| nead for the rectifier.
>
>That's _why_ I suggested solar ... because it does not need a rectifier.
But it needs the cells, battery, wiring for it, when there
is an existing AC grid ready for the purpose. These parts
also have loss in manufacturing, minor loss in use. If it
were a better general way to power a computer, that's what
we'd be using.
>It's just a special case that _maybe_ someone might have at some point.
Well yes some have used solor power, I believe http://www.tomshardware.com has such a project ongoing and
has written an article or two about it. However I don't
recall the details of their plan, didn't think it involved
generating 340-odd VDC, probably lower voltage then a DC-DC
supply or inverter.
>It's certainly not a normal case, at least not to run the solar power
>directly into the post-rectifier stage of the PSU. Of course they would
>have to be sure they are getting sufficient voltage from the solar array
>without an overvoltage.
There is something else being overlooked though, that often
solar systems also have a rectifier between panels and
battery array.
>
>Lots of PSUs these handle the full 100-240 VAC range, so they do have a
>means to work on anything in between without switching to voltage doubling.
>I don't know if the DC stage (where you typically see 340 VDC) is where
>the wide voltage swing happens (e.g. 140-340 VDC for 100-240 VAC in), but
>if it is, then direct solar probably could be configured to that range and
>made to work. If they wanted to (I don't care to).
Wide input range units (without a switch to select voltage)
tend to be active PFC type, using a voltage boost circuit
(something like a fet switched inductor) to reach a point
at least a few dozen volts above 340V. If you really really
wanted to go all out and save every last fraction of a
percent in efficiency, these active PFC PSU would not be
used as there is no need for active PFC if there were a high
voltage DC supply, it is then just another point of loss in
the PSU.
>I never said you have to build it from scratch. For building structure
>wiring (where you have the AC-DC in a separate room from the DC utilization)
>then you have to buy listed and rated breakers. What I did was explain why
>breakers for DC have to be designed better than for the same AC voltage.
Ok, but fortunately we don't have to design, just by all
these special parts... I mean if I thought it was a useful
goal.
>| You're trying to make distinctions where there aren't any.
>| The same fault protection topology is needed either way,
>| it's just the means towards that end that differs in
>| component selection.
>
>The legal requirements for breakers inside equipment is different than
>for breakers protecting building wiring (which must be involved if you
>feed the power in question through building walls).
Didn't "differs in component selection" already cover that?
>
>You would have to put a breaker at each point where you want to limit
>the scope of outages caused by breaker tripping. If you have multiple
>loads on a UPS, do you want to bother with a separate breaker on each
>one, or just one for the whole UPS output. Each situation will differ.
>For very large UPSes powering lots of computers, then yes, many breakers
>is a good idea.
>
>Nevertheless, if you have a DC source in a different room of the building,
>then you _must_ have a breaker at that DC source, in addition to any others
>you may have. That is because what is being protected is the wiring that
>is in the building. Having individual breakers at each DC utilization is
>fine, but you cannot depend on only that. The electrical code requires
>the protection on all building wiring. Just because it is DC does not get
>you a free pass. The NEC covers DC as well.
I didn't say it didn't need a breaker, you were suggesting
that breaker should trip upstream of an invertor that was
not causing a fault condition on that supply line to the
invertor, rather a fault on the invertor output... which
should only break the circuit at the point of the fault
which is at the inverter, not upstream of it until the
inverter itself causing this secondary problem which it may
not, actually should not ever because it has it's own
inbuilt breaker, fuse, and probably overcurrent shutdown
circuit.
>On Thu, 04 Oct 2007 11:22:19 -0400 kony <spam@spam.com> wrote:
>
>|>Maybe someone could make such a device entirely in a power supply form
>|>factor?
>|
>| I fail to see what purpose that would have, since it's not
>| as though we'd have a system without the main power supply
>| and very few cases can accomdate two PS2/ATX supplies. I
>| suspect we were talking about putting it in one or two 5
>| 1/4" bays because that's the only likely available space in
>| a typical computer case. Most people don't have more than
>| one, maybe two optical drives and most midtower cases have
>| at least 3, 5 1/4 bays unless we also consider many of the
>| OEM systems which have only two bays, but these typically
>| come with only one optical drive so there is still one bay
>| available.
>
>Many computers I have seen with dual/redundant PSUs have half
>size PSUs. Use that half size design and make a battery box
>in the other half. If the port for redundant PSUs can supply
>power from one to the other, it might be plausible to make a
>battery box that plugs straight in to where redundant PSUs
>plug in.
yes that might work, but it's also going to drive up the
cost further and I still feel the short runtime couldn't
justify the cost of doing it in even the cheapest way
possible.
>
>Someone might consider the capacitors, even if more costly than
>a cheap UPS, to be a good choice because it fits inside the case.
I doubt it, there's just not many scenarios where you can't
fit a small external UPS as it's not that large relative to
the computer itself, or the user, or anything else in a
typical office. Outside a typical office, maybe there would
be some special application for it, but it would seem a bit
backwards to design a thing without a clear application and
then go looking for one. Capacitors definitely won't
provide more than a few seconds of runtime, within normal
volumes being discussed) that's a very high cost for
coverage of only very short power interruptions.
>
>Some cases these days are made with PSU at the bottom. Maybe
>they can just make a case with a full length space at the bottom
>for a complete UPS-like integrated power system much like the OP
>seems to want.
Why not just use the external UPS and put the case on top of
it? I seem to be stuck on this idea of external being
better for most practical uses, so I doubt I'll be adding
much more to this thread.
kony wrote:
> On Tue, 02 Oct 2007 17:19:06 -0700, meow2222@care2.com
> wrote:
>
>
> >> To arrive at ~ 5V alone it could be done, but to remain at ~
> >> 5V under high current may not be so easy with sub-C cells.
> >
> >Neither of us really knows what size cells, but of course theyll be
> >sized for the job. However given that D cells can knock out 60A
> >there doesnt seem much doubt that it'll all fit in a standard 5.25"
> >case.
>
> With Sub-C yes, but I am not convinced you could get enough
> D cells plus supportive circuitry including the connectors,
> wiring harness, etc, in that space (not just volume but also
> the form factor dimensions.
>
> Maybe it simply uses two drive bays instead, if the case has
> the bays that isn't a problem. If it were important to have
> this internal I would just as soon select a case with two
> bays available so as to be able to reach higher capacity.
>
>
>
> >I'd look at NiFe rather than NiCd though. With their very high
> >current ability they can be made smaller and more V stable.
>
> It'll drive the price up even more when it seems cost
> prohibitive already vs a standard external UPS.
>
> >> The motors don't care if the voltage drops while a PC does.
> >> Running a pack with a tap in it to derive 5V and 3V power
> >> might be too much current to keep voltage up. Even so, D is
> >> definitely an improvement and yet getting ever closer to
> >> exceeding available space in a drive bay. Remember it's not
> >> just the batteries but the circuit, insulating material or
> >> standoffs, the incoming and outgoing connectors or wiring
> >> harness.
> >
> >those other parts are fairly small volume-wise.
>
> Each alone, yes, but they'll all have to be on a circuit
> board isolated and/or mounted to the casing in the rear, and
> all these low volume parts add up, as well as requiring
> fairly beefy wiring or traces to keep voltage drop to a
> minimum since it is already a large concern by extending the
> primary PSU harness to this circuit, through it and away
> from it. Maybe it's not impossible but to know for sure
> with a given battery cell size you will have to make a
> prototype or at least a detailed model.
>
>
>
> >> Some might only need to avoid losing data, but how many
> >> would take a device with lesser versatility and capacity
> >> just to save a bit of space outside of the PC while taking
> >> up space and having to route a second thicker wiring harness
> >> inside the PC?
> >
> >I'm not planning any extra wiring required inside the PC. Why do you
> >think there would need to be? V_drop too high?
>
> Yes, as well as degradation of the wiring and connectors.
> You can't just push multiple times as much current through
> these connectors and wiring for more than a few seconds
> without it causing a problem and even for a few seconds
> there is definitely going to be a voltage drop. Given brief
> enough runtime that these parts stay within thermal
> thresholds, you could just factor for the lower delivered
> voltage and start out with a higher supply voltage, but this
> current supplied will vary per system so it becomes more
> complex to calculate or not a universal solution because you
> have multiple variable factors effecting whether your
> battery supply remains within the upper and lower limits the
> system needs, particularly for 3.3 and 5V. You could make
> it all easier by just using a regulated (switching) supply
> after the battery, but this also raises the cost and size.
>
>
> >
> >Why would a business user choose an inbuilt miniups?
> >1. Because they dont want to fork out on a large whole site UPS, nor
> >have loads of mains plugin UPSes cluttering up the place.
>
> As I'd stated previously, there is no new technology
> suddenly making this possible where it wasn't before. I
> have not heard of any demand for such a product except this
> one thread on usenet.
>
> >2. Lower cost than an external plugin UPS
>
> ... but it's not, I guarantee this won't sell for less than
> a $30 UPS. I'm thinking due to low volume the retail price
> would be closer to $200. Remember, it's not just bare parts
> costs, there's construction, development, advertising,
> distribution, etc, and then there's the profit that has to
> be made off the product.
>
>
> >3. Ease: just tick the box on the form and you get a data-safe PC.
> >4. Any company PCs used offsite will always be UPS protected
> >this way
>
> Maybe I'm wrong and your idea puts you one step away from
> millions in profit... but I doubt it. Build a prototype and
> try it with multiple varying platforms. Keep a BOM and then
> take a poll of who will pay $X for Y performing internal
> UPS.
>
>
> >
> >
> >> There's also another problem in that PC PSU
> >> with rail sense leads use these to sense at the ATX
> >> connector under the presumption it is plugged into the load,
> >> while the resultant voltage at the load will be lower than
> >> it senses due to the intermediate stage of having to go
> >> through the battery pack subcircuit.
> >
> >main psu doesnt go through the batt pack, the wiring in the pc is
> >not affected, the miniups just plugs into a molex connector, end of
> >job.
>
> It has to have the main psu running through it.
>
> Remember, the computer has to get power from both supplies.
> They both have to be wired to the (motherboard for example)
> part powered to deliver the power to it, BUT you can't just
> use a splitter, because the output from the battery pack
> being commonly connected to the main PSU would result in
> high current into the battery pack or vice versa, depending
> on which had a higher actual voltage level. With more
> sophisticated electronics this could be overcome but not as
> you'd described it. The cheapest solution would be to just
> use isolation diodes, but once again the volume of the parts
> goes up, towards being too big to fit in the bay space.
>
>
>
>
> >If running the Pc's original wiring loom proves too high a
> >V_drop
> >to set the batt pack out a little higher and run it open loop, then
> >there would also need to be an exrta sense wire tagged on. Very
> >easy.
>
> As I mentioned above, you can't just connect it to the PSU
> wiring harness, because you have two supplies with
> inevitably, slightly different voltage levels. With an
> isolation method you could use the PSU wiring harness but
> you still have to break that wiring harness by splicing into
> it before it gets to the components from the PSU, or have an
> inbuilt circuit on the internal UPS to do this.
>
>
>
> >
> >
> >> >> Also we haven't even considered the little odds and ends to
> >> >> implement this, like the wiring harnesses, connectors, etc,
> >> >> requiring the primary AC-DC PSU to input to this battery
> >> >> pack
> >> >
> >> >I think we may have been talking at cross purposes then. I was
> >> >proposing doing away with all that, just trickle charging the battery
> >> >pack from the PC's molex connector. Would need nothing more
> >> >than a basic bottom price linear regulator.
> >>
> >> Pack input isn't the problem, that'll work for charging but
> >> you still need to isolate the two supplies from each other.
> >> You have two power sources and you have input to the pack
> >> through this regulator, but it still has to get to the
> >> motherboard without being a common rail to the PSU, and both
> >> have to be plugged into everything so the original PSU plus
> >> then has to be unplugged (else a lot of ugly grafting of
> >> leads onto the existing PSU wiring harness) . Thus, you
> >> have to unplug the PSU from the mobo and put it's connector
> >> onto another circuit board (or dongle style split) along
> >> with the output from the battery pack to the motheboard and
> >> other components needing power.
> >
> >You're way overcomplicating this. The battery pack output stays
> >connected via a relay whenever the machine is on.
>
> You mean disconnected, right? If so, ok BUT this is yet
> another part taking up space that had not been mentioned
> yet, and multi-pole or multiple relays capable of this much
> DC current aren't particularly small, and further PCB space
> and traces continue to add to the volume required.
>
>
>
> >At power down
> >it senses that and continues supplying power for 15s (ie it doesnt
> >distinguish mains failure from normal power down) then cuts out.
>
> 15 seconds is not long enough to make this product worth
> buying/owning/etc, IMO.
>
> It may also need to distinguish mains failure from normal
> power down.
>
>
>
> >
> >A possible way to control charging is to connect the half way point
> >on the batt pack to each rail (0v or 12v) via a basic reg, thus
> >charging each half of the pack alternately. Doide & R ensures the
> >pack and its halves can discharge very fast but only charge at a
> >trickle.
>
> ?? What do you mean connect the half way point?
>
> Yes you could get a usable result with resistors and diodes,
> providing all parts are suitably spec'd. It still may not
> be a univeral solution since different systems have
> different current requirements and the voltage will vary
> based on current. IMO, it really needs to stay within ATX
> specs which is 5%. I suspect a difference in current from
> one system to the next, alone will exceed this 5% meaning it
> would have to be custom designed for each system...
> something an OEM could do but would eliminate it from being
> an aftermarket product unless the system integrator knows
> exactly how to spec the current requirement and there were
> multiple models of this internal UPS to meet each different
> system requirement.
>
> It would be much easier to just use a DC-DC switching
> regulator supply after the battery pack. That makes it
> nearly universal (within the current capability it can
> handle as a max. amount).
>
>
>
> >
> >
> >> >Same molex serves the
> >> >PC with power during the mini-ups's brief run. I dont know what the
> >> >continuous current rating of those molexes is, but if the UPS only
> >> >powers the system for 20 seconds its not going to be a problem.
> >>
> >> 6A, IIRC, but there's the voltage drop problem across the
> >> connector and single supply leads making it too lossy.
> >
> >Do you know what the R or range of R is? I've not measured it. The
> >ATX Vspec allows a fair amount of swing IIRC
>
>
> If the system has enough power interruptions to make this
> UPS viable, we're talking about a continual overcurrent
> which will degrade the connectors (first, and then wiring).
> The ATX spec allows 5% but with battery voltage dropping
> while discharging, battery voltage dropping with changes
> (increases) in current, and the wiring plus connectors
> causing further drop with increases in current, very quickly
> the UPS needs matched to a system within a certain current
> usage, and this also greatly depends on what that system is
> doing at the moment the power goes out since it is very easy
> for modern processors/GPU/etc to have changes in current
> over 30% if not a lot more.
>
>
>
> >
> >> You'll also have to switch the lead from input to output
> >> around the charging circuit if I understand what you're
> >> suggesting,
> >
> >trying to avoid any such switching if poss. If we switched the batt
> >pack between charge and out, a power failure would mess with the
> >pc before the relay clicked in.
>
> Well... for the purposes of what I wrote, a relay is a
> switch.
>
>
> >> then have the power going through these single
> >> supply leads up to the PSU wiring harness distribution point
> >> and down into the main PSU harness, which is quite a
> >> distance to travel for the currents in a PC.
> >
> >yeah. If too much R and load variation we could resort to an extra
> >sense wire to fix it. That would require a high current reg though,
> >best avoided if poss.
>
> The sense wire would need to be from the load to the
> feedback in the main PSU, meaning the system as it started
> can't remain intact, it has to have the PSU wiring modified
> regardless of whether that went to the UPS before the
> components.
>
> As for a sense wire from the UPS to the load, that too would
> be a good approach to take to keep the voltage right, as a
> feedback to the UPS which has a regulation stage on the
> output. This is really the only universal solution to
> ensure compatibility, the way it needs to be done to work
> well. As for high current regulator, you want a switching
> regulator circuit anyway not a linear because linear is too
> lossy. A typical voltage drop across one might be roughly
> 1.5 to 2.5V, which times at least a dozen amps total as a
> sum of all power rails to power the system, is 18W+ loss,
> reducing the battery pack's runtime. An LDO linear could be
> used instead with lower loss but still it's a significant
> loss when running from battery power and with the battery
> capacity constrained by available space in a drive bay.
>
> The current isn't necessarily much of a problem for the
> regulator though, as I'd mentioned in a past rely all one
> would have to do is put a pass transistor into the regulator
> subcircuit. Examples of this can be found in some linear
> regulator datasheets, for example I think National's LM317
> datasheet has one.
>
> http://www.national.com/ds.cgi/LM/LM117.pdf
> pg 16, but using pass transistor(s) capable of the current
> instead of the default 3 * LM195 shown.
>
> I went off on a tangent there, a switching supply output
> from the pack is really the best alternative.
>
> >> An OEM could come closer to the goal because they can limit
> >> the unit's compatibility with certain systems' unique
> >> current requirements. On the other hand we'd be cursing all
> >> that much more about the proprietary way they ended up
> >> getting the job done, OEMs don't need much of an excuse to
> >> do screwy things that make it either impossible or very
> >> costly to replace anything... keeping in mind that even if
> >> the mini-UPS were to work there will always be a certain
> >> failure rate and replacement requirement.
> >
> >They do things proprietary ways mainly because they can save
> >money. 20p off 10,000 units is £200, os if they can do it non
> >standardly for a few p less they will. But I dont see proprietary vs
> >not having a big effect on viability.
>
> Proprietary vs univeral means the OEM can determine the
> current consumption per rail of the target system, and match
> the DC ups to it. Without having the target system's
> current requirement there is another variable in whether the
> UPS' DC output stays in spec, unless it has the regulation
> stage following it before the load and ideally the feedback
> remote sense lead.
>
>
>
> >One PC mfr would only capture
> >part of the market, but people buying new systems are an attractive
> >target for addons, especially if they promise to safeguard against
> >business data corruption or loss, and do it at lower cost than
> >anyone else's UPS, and with less hassle..
>
> yes, and that is exactly why it needs the regulation stage
> to make it universal instead of just running straight from
> the pack to the load, which is basically the same reason why
> a switching main PSU also needs (already has) a feedback
> loop so it can adjust for differing loads.
hope you got the reply, it hasnt showed up on this server yet.
On Thu, 04 Oct 2007 16:47:02 -0400 kony <spam@spam.com> wrote:
|>Maybe if you work out the math for all the other parts in the PSU,
|>maybe we can see where the other 99% of the power is lost.
|
| There isn't 100% power lost, if there were there wouldn't be
| any output to the system.
I think I figured out where the difference is. We were not talking
about the same thing. You were giving the percentage of the overall
power UTILIZATION that the rectifier represented as a loss, whereas
I was giving the percentage OF THE LOSS that the rectifier contributed.
|>That's _why_ I suggested solar ... because it does not need a rectifier.
|
| But it needs the cells, battery, wiring for it, when there
| is an existing AC grid ready for the purpose. These parts
| also have loss in manufacturing, minor loss in use. If it
| were a better general way to power a computer, that's what
| we'd be using.
I'm not saying solar is a better way to power a computer. But it might
get uused in some cercumstance "because it is there". If I were doing
it, I'd rather have the solar charge a bank of batteries that drive a
set of paralleled inverters to produce AC and run the AC through the
whole house. Other power source (utility, generator, windmill, etc)
would also be driving the battery charging, if I had a system like that
(I'd like to, but I don't right now).
--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / spamtrap-2007-10-04-2326@ipal.net |
|------------------------------------/-------------------------------------|
On Thu, 04 Oct 2007 16:55:38 -0400 kony <spam@spam.com> wrote:
| I doubt it, there's just not many scenarios where you can't
| fit a small external UPS as it's not that large relative to
| the computer itself, or the user, or anything else in a
| typical office. Outside a typical office, maybe there would
| be some special application for it, but it would seem a bit
| backwards to design a thing without a clear application and
| then go looking for one. Capacitors definitely won't
| provide more than a few seconds of runtime, within normal
| volumes being discussed) that's a very high cost for
| coverage of only very short power interruptions.
In my office (a downtown location on "network power") I have never seen
any outage longer than a blink. Those a possibly caused by some end of
the secndary network experiencing a fault and tripping out. But they
typically take out well more than half the computers that are not on a
UPS. We use rather small UPSes because such blinks is all we really
ever see.
Suburban and rural locations would be worse off. I live in a rural
location and when power goes out here, I typically see 3 recloser
actions with increasing outage times. Causes are typically trees
falling onto utility distribution (12.47kV) lines (yes, the trees
are well above them out here).
|>Some cases these days are made with PSU at the bottom. Maybe
|>they can just make a case with a full length space at the bottom
|>for a complete UPS-like integrated power system much like the OP
|>seems to want.
|
| Why not just use the external UPS and put the case on top of
| it? I seem to be stuck on this idea of external being
| better for most practical uses, so I doubt I'll be adding
| much more to this thread.
Personally, I'm all for the external, too. I'm just holding off to find
the right set of parts to put together a 240 volt system (with a small
transformer to make some 120 volts for a small few things that might not
handle 240). Then I can handle those phase loss brownouts (we've had 2
of those in as many years, lasting a couple hours each).
--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / spamtrap-2007-10-04-2341@ipal.net |
|------------------------------------/-------------------------------------|
>On Thu, 04 Oct 2007 16:47:02 -0400 kony <spam@spam.com> wrote:
>
>|>Maybe if you work out the math for all the other parts in the PSU,
>|>maybe we can see where the other 99% of the power is lost.
>|
>| There isn't 100% power lost, if there were there wouldn't be
>| any output to the system.
>
>I think I figured out where the difference is. We were not talking
>about the same thing. You were giving the percentage of the overall
>power UTILIZATION that the rectifier represented as a loss, whereas
>I was giving the percentage OF THE LOSS that the rectifier contributed.
I see what you mean. As percent loss, it'd be closer to
that 1%/25% total efficiency losses = 4%
Re: DC-DC UPS? 
Linear Mode
