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Sci.Electronics.Basics -> power filters
There are 27 messages in this thread.
You are currently looking at messages 20 to 27.
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Author: Charlie SiegristDate: 23:36 21-07-07
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On Fri, 20 Jul 2007 01:27:47 GMT, in message
<46A00F96.1DD423A7@earthlink.net>, "Michael A. Terrell"
<mike.terrell@earthlink.net> scribed:
>CptDondo wrote:
>>
>> Michael A. Terrell wrote:
>>
>> > Only in 'on line' UPS systemms. BTW, the smallest online UPS I've
>> > seen was 15 KW. Even then, there were manual switches to bypass the
>> > system, for maintanence.
>>
>> A bit of googling will find them as small as 500va.
>
>
> At what price and efficiency?
The Falcon SSG500 has an efficiency of 85%, and might be the model Cap'n
Doodo is referencing. Couldn't find a price in a cursory search, but it
seems Allis-Chalmers is pleased with the product:
<http://www.oilonline.com/news/headlines/firms_faces/20070612.Falcon%E2%80%99s.23797.
asp>
Brings to mind the old saw, "If you have to ask, you can't afford it."
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Author: Charlie SiegristDate: 23:57 21-07-07
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On Thu, 19 Jul 2007 18:04:48 -0400, in message
<J1Rni.43$9C1.3@newsfe04.lga>, Jamie
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> scribed:
>CptDondo wrote:
>
>> Michael A. Terrell wrote:
>>
>>>
>>>
>>> So, these don't even try to match the line frequency or phase before
>>> they switch over? What a nasty design.
>>
>> I think you're missing the point. If I understand this correctly, there
>> is no "switch".
>>
>> The "UPS" takes AC to DC, charges a battery. Then there is an
inverter
>> that takes DC from the battery and provides AC.
>>
>> There is no AC - AC connection or switch; the unit is *always* fed from
>> the inverter, and *never* from the grid.
>>
>I'm glad some one understands it. :)
Yes, but I'm afraid neither you nor the Cap'n fully understand. As the
other sub-thread is showing, the above description of how the UPS operates
is that of an "online" UPS. Unless you know that you have an online model,
you can't rely on the description given being accurate. Here's a site that
sells UPS:
<http://www.powerqualityinc.com/batterybckupf.htm>;
Note that there are three types listed: online, standby, and
line-interactive. The line-interactive is still a standby UPS, but has
faster response to failure.
<http://www.smeco.com/products/protecting/UPSlist.html>;
Note that the Powerware Prestige 650 can be had new for about $550, and
give online performance and true sine wave output. (That's another point
about UPS - the output. Some UPS inverters have a very dirty stepped sine
output.) Efficiency is probably around 90% (I found 93% listed for their
3000VA unit).
So, in order for understanding to be complete, one must know what unit one
possesses. This is a really good page for study:
<http://www.pcguide.com/ref/power/ext/ups/index.htm>;
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Author: Charlie SiegristDate: 23:59 21-07-07
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On Thu, 19 Jul 2007 18:11:07 -0400, in message
<C7Rni.44$9C1.3@newsfe04.lga>, Jamie
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> scribed:
>> So, these don't even try to match the line frequency or phase before
>> they switch over? What a nasty design.
>>
>>
>No , they don't match the line freq. the output is from the inverter at
>all times. the inverter is operating from a DC supply which is the
>battery which gets charged from the line..
I would be very surprised to learn that your online UPS is not synced to
the line feed. Can you verify that via make and model? Thanks.
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Author: Charlie SiegristDate: 00:08 22-07-07
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On Sun, 22 Jul 2007 02:41:26 GMT, in message
<46A2C3D9.16E5AF8D@earthlink.net>, "Michael A. Terrell"
<mike.terrell@earthlink.net> scribed:
>Charlie Siegrist wrote:
>>
>> The Falcon SSG500 has an efficiency of 85%, and might be the model Cap'n
>> Doodo is referencing. Couldn't find a price in a cursory search, but it
>> seems Allis-Chalmers is pleased with the product:
>>
>>
<http://www.oilonline.com/news/headlines/firms_faces/20070612.Falcon%E2%80%99s.23797.as
p>
>>
>> Brings to mind the old saw, "If you have to ask, you can't afford
it."
>
>
> That's why most people have to settle for off-line UPS equipment. I
>could have bought a used online sine wave UPS big enough to power
>everything in my house for $100. It was almost two tons, and only
>needed about $5000 worth of new batteries that had to be replaced every
>two years. So, it would have cost over 2.5 times my current electric
>bill, plus the cost of extra electricity for air condoning.
Ah yes, of course, the batteries. APC makes a good standby UPS, but expect
to change its battery every three years, and that's not terribly cheap.
Two years ago I hired on at a new company. One of my first engineering
decisions involved an UPS. The technician wanted to throw out a small APC
unit when it stopped functioning correctly. I asked him when was the last
time he changed the battery. He replied, "Battery?" Not that he was a bad
tech, he just had a limited knowledge base.
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Author: Michael A. TerrellDate: 01:00 22-07-07
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Charlie Siegrist wrote:
>
> Ah yes, of course, the batteries. APC makes a good standby UPS, but expect
> to change its battery every three years, and that's not terribly cheap.
> Two years ago I hired on at a new company. One of my first engineering
> decisions involved an UPS. The technician wanted to throw out a small APC
> unit when it stopped functioning correctly. I asked him when was the last
> time he changed the battery. He replied, "Battery?" Not that he was a
bad
> tech, he just had a limited knowledge base.
My first APC last for over five years on the OEM battery. Sine then,
I've had so many given to me that I haven't needed to buy batteries in
over 10 year. Yes, the batteries do fail, especially when the electric
goes out often, and the computer isn't set up to shut down.
Right now I have at least 12 spares with usable batteries, and I could
probably get several hundred more per year, for free. Replacement
batteries aren't that bad, bought in bulk. APC is very high, compared
to OEM and surplus sources. I used to pick up used Gates battery packs
from a Diebold repair center, and sell them to amateur radio operators
for standby power. they still bug me for more cheap batteries, but the
source is gone. I also have several new 17 AH 12 VDC gel cells from
those portable starter packs for cars. I'm tempted to use them as
external batteries on a pair of old 1000 VA APC UPS I have in storage
for my server and web design computers. The 650 VA APC can't handle the
computer and HP 1130 monitor, and odds and ends in my office.
--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.
Michael A. Terrell
Central Florida
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Author: Captain DondoDate: 10:48 24-07-07
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V Sat, 21 Jul 2007 19:57:15 -0800, Charlie Siegrist napsal(a):
> On Thu, 19 Jul 2007 18:04:48 -0400, in message
> <J1Rni.43$9C1.3@newsfe04.lga>, Jamie
> <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> scribed:
>>>
>
>>I'm glad some one understands it. :)
>
> Yes, but I'm afraid neither you nor the Cap'n fully understand. As the
> other sub-thread is showing, the above description of how the UPS operates
> is that of an "online" UPS. Unless you know that you have an online
model,
> you can't rely on the description given being accurate.
That's the exact point, and what I was looking for. Don't assume everyone
who asks a question is ignorant...
And don't assume that efficiency and cost (as in the other subthread) are
an issue... (15KW generator running a machine that's a quarter mile long
- do you think anyone is going to care if a 500VA UPS is 85% efficient?
Or that it costs US$500?)
:-)
--Yan
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Author: Charlie SiegristDate: 21:00 27-07-07
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On Tue, 24 Jul 2007 14:48:43 -0000, in message
<13ac4ab818ael87@corp.supernews.com>, Captain Dondo <yan@NsOeSiPnAeMr.com>
scribed:
>V Sat, 21 Jul 2007 19:57:15 -0800, Charlie Siegrist napsal(a):
>
>> On Thu, 19 Jul 2007 18:04:48 -0400, in message
>> <J1Rni.43$9C1.3@newsfe04.lga>, Jamie
>> <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> scribed:
>
>>>>
>>
>>>I'm glad some one understands it. :)
>>
>> Yes, but I'm afraid neither you nor the Cap'n fully understand. As the
>> other sub-thread is showing, the above description of how the UPS operates
>> is that of an "online" UPS. Unless you know that you have an online
model,
>> you can't rely on the description given being accurate.
>
>That's the exact point, and what I was looking for. Don't assume everyone
>who asks a question is ignorant...
I try never to make such an assumption. At this point in the conversation,
however, I have no idea whatsoever what your exact point is, or for what
you are looking.
>And don't assume that efficiency and cost (as in the other subthread) are
>an issue... (15KW generator running a machine that's a quarter mile long
>- do you think anyone is going to care if a 500VA UPS is 85% efficient?
>Or that it costs US$500?)
Yes, actually, cost and efficiency are a consideration in any engineering
procurement decision. That's not an assumption, that's a fact. Budgets
are not bottomless, as much as an engineering team might want them to be.
And I wonder, what good is a 500VA UPS in maintaining a 15KW load?
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