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UPS design (APC Back-UPS 650)
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P E Schoen
Mar 31, 2012, 2:45:55 AM3/31/12
to
I have an old UPS unit that I found in a trash pile at a Hamfest probably 5
or more years ago, and I figured I might be able to use it as a 12 VDC to
120 VAC inverter. So I opened it up, and removed the two 6V SLA batteries
(which had cracked, probably from freezing). I had thought the weight of the
unit (about 22 lb.) was from the batteries, but there is also a rather large
(3.5" x 4" x 4") transformer which probably weighs at least 10 lb. I had
expected a much smaller ferrite transformer such as found in most inverters.
So I thought maybe it was used in such a way as to create a good waveform,
but when I powered the unit with a 12V supply (1.08A), I found that it was a
"modified sine wave" which was just a series of positive and negative pulses
175 V peak and 2.6 mSec wide with a period of 17.2 mSec (57 Hz), and it has
an overshoot at turn-off. This indicates that it is not being driven by a
true bridge but just a very simple PWM push-pull drive. I found two heat
sinks, each of which have four TO-220 devices, and I found a rectangular
pulse train 11.5 volts and 3.6 mSec wide, so they must be MOSFETs.
It has quite a large and complex PCB, with a 4" x 6" section having about 10
DIP ICs and associated components. No SMDs. The unit has a DB-9 serial port
for computer connection. The date on the PCB is 1997. There does not appear
to be any sort of microprocessor or "smarts", and the only IC I did not
recognize was an MF4CN-50 which is a low pass filter
http://www.datasheetcatalog.org/datasheet/nationalsemiconductor/DS005064.PDF.
So, what does the serial port connection do, and how does it do it? Here is
the user manual: http://www.apcmedia.com/salestools/ASTE-6Z7UZ8_R0_EN.pdf
I don't think there's much value to this thing, except maybe the big tranny
which might make a good high current low voltage supply. Probably about 15
VCT at 30 amps or so.
Are more modern UPS units made this way? Seems strange not to use high
frequency magnetics to generate a 175 VDC rail and then use a bridge to
generate the output waveform. And now that it's easy to make a PWM inverter
with a high frequency carrier like a motor control, a fairly good sine wave
could be made. And a crystal could be used to get a very accurate 50 or 60
Hz waveform, although it's usually not much needed except for an alarm
clock. Actually, most computer equipment uses switching supplies and
probably would operate just as well, if not better, with the straight DC
rail (although perhaps at less than the 175 volts).
Any thoughts? Thanks.
Paul
or more years ago, and I figured I might be able to use it as a 12 VDC to
120 VAC inverter. So I opened it up, and removed the two 6V SLA batteries
(which had cracked, probably from freezing). I had thought the weight of the
unit (about 22 lb.) was from the batteries, but there is also a rather large
(3.5" x 4" x 4") transformer which probably weighs at least 10 lb. I had
expected a much smaller ferrite transformer such as found in most inverters.
So I thought maybe it was used in such a way as to create a good waveform,
but when I powered the unit with a 12V supply (1.08A), I found that it was a
"modified sine wave" which was just a series of positive and negative pulses
175 V peak and 2.6 mSec wide with a period of 17.2 mSec (57 Hz), and it has
an overshoot at turn-off. This indicates that it is not being driven by a
true bridge but just a very simple PWM push-pull drive. I found two heat
sinks, each of which have four TO-220 devices, and I found a rectangular
pulse train 11.5 volts and 3.6 mSec wide, so they must be MOSFETs.
It has quite a large and complex PCB, with a 4" x 6" section having about 10
DIP ICs and associated components. No SMDs. The unit has a DB-9 serial port
for computer connection. The date on the PCB is 1997. There does not appear
to be any sort of microprocessor or "smarts", and the only IC I did not
recognize was an MF4CN-50 which is a low pass filter
http://www.datasheetcatalog.org/datasheet/nationalsemiconductor/DS005064.PDF.
So, what does the serial port connection do, and how does it do it? Here is
the user manual: http://www.apcmedia.com/salestools/ASTE-6Z7UZ8_R0_EN.pdf
I don't think there's much value to this thing, except maybe the big tranny
which might make a good high current low voltage supply. Probably about 15
VCT at 30 amps or so.
Are more modern UPS units made this way? Seems strange not to use high
frequency magnetics to generate a 175 VDC rail and then use a bridge to
generate the output waveform. And now that it's easy to make a PWM inverter
with a high frequency carrier like a motor control, a fairly good sine wave
could be made. And a crystal could be used to get a very accurate 50 or 60
Hz waveform, although it's usually not much needed except for an alarm
clock. Actually, most computer equipment uses switching supplies and
probably would operate just as well, if not better, with the straight DC
rail (although perhaps at less than the 175 volts).
Any thoughts? Thanks.
Paul
Nico Coesel
Mar 31, 2012, 8:13:05 AM3/31/12
to
"P E Schoen" <pa...@peschoen.com> wrote:
>I have an old UPS unit that I found in a trash pile at a Hamfest =
>probably 5=20
>or more years ago, and I figured I might be able to use it as a 12 VDC =
>to=20
>120 VAC inverter. So I opened it up, and removed the two 6V SLA =
>batteries=20
>(which had cracked, probably from freezing). I had thought the weight of =
>the=20
>unit (about 22 lb.) was from the batteries, but there is also a rather =
>large=20
>(3.5" x 4" x 4") transformer which probably weighs at least 10 lb. I had =
>
>expected a much smaller ferrite transformer such as found in most =
>inverters.
>
>PDF.=20
>So, what does the serial port connection do, and how does it do it? Here =
>is=20
>the user manual: =
>http://www.apcmedia.com/salestools/ASTE-6Z7UZ8_R0_EN.pdf
>
>I don't think there's much value to this thing, except maybe the big =
>tranny=20
>which might make a good high current low voltage supply. Probably about =
>15=20
Yes. Its more or less APC's standard recipy for up to 2500VA. This
design is very reliable. I've never seen one fail.
--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
nico@nctdevpuntnl (punt=.)
--------------------------------------------------------------
>I have an old UPS unit that I found in a trash pile at a Hamfest =
>probably 5=20
>or more years ago, and I figured I might be able to use it as a 12 VDC =
>to=20
>120 VAC inverter. So I opened it up, and removed the two 6V SLA =
>batteries=20
>(which had cracked, probably from freezing). I had thought the weight of =
>the=20
>unit (about 22 lb.) was from the batteries, but there is also a rather =
>large=20
>(3.5" x 4" x 4") transformer which probably weighs at least 10 lb. I had =
>
>expected a much smaller ferrite transformer such as found in most =
>inverters.
>
>PDF.=20
>So, what does the serial port connection do, and how does it do it? Here =
>is=20
>the user manual: =
>http://www.apcmedia.com/salestools/ASTE-6Z7UZ8_R0_EN.pdf
>
>I don't think there's much value to this thing, except maybe the big =
>tranny=20
>which might make a good high current low voltage supply. Probably about =
>15=20
>VCT at 30 amps or so.
>
>Are more modern UPS units made this way? Seems strange not to use high=20
>
Yes. Its more or less APC's standard recipy for up to 2500VA. This
design is very reliable. I've never seen one fail.
--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
nico@nctdevpuntnl (punt=.)
--------------------------------------------------------------
Don Y
Mar 31, 2012, 4:57:48 PM3/31/12
to
Hi Paul,
On 3/30/2012 11:45 PM, P E Schoen wrote:
> I have an old UPS unit that I found in a trash pile at a Hamfest
> probably 5 or more years ago, and I figured I might be able to use it as
> a 12 VDC to 120 VAC inverter. So I opened it up, and removed the two 6V
> SLA batteries (which had cracked, probably from freezing). I had thought
> the weight of the unit (about 22 lb.) was from the batteries, but there
> is also a rather large (3.5" x 4" x 4") transformer which probably
> weighs at least 10 lb. I had expected a much smaller ferrite transformer
> such as found in most inverters.
>
> So I thought maybe it was used in such a way as to create a good
> waveform, but when I powered the unit with a 12V supply (1.08A), I found
> that it was a "modified sine wave" which was just a series of positive
> and negative pulses 175 V peak and 2.6 mSec wide with a period of 17.2
> mSec (57 Hz), and it has an overshoot at turn-off.
Yes. It's not even a "stepped sine wave" -- think of the primary
as a center tapped coil with FETs tugging alternately on one
side, then the other.
The "difference" between various VA models is the number of
FETs paralleled for each "side" of the coil.
> This indicates that
> it is not being driven by a true bridge but just a very simple PWM
> push-pull drive. I found two heat sinks, each of which have four TO-220
> devices, and I found a rectangular pulse train 11.5 volts and 3.6 mSec
> wide, so they must be MOSFETs.
>
> It has quite a large and complex PCB, with a 4" x 6" section having
> about 10 DIP ICs and associated components. No SMDs. The unit has a DB-9
> serial port for computer connection. The date on the PCB is 1997. There
> does not appear to be any sort of microprocessor or "smarts", and the
> only IC I did not recognize was an MF4CN-50 which is a low pass filter
> http://www.datasheetcatalog.org/datasheet/nationalsemiconductor/DS005064.PDF.
> So, what does the serial port connection do, and how does it do it? Here
> is the user manual:
> http://www.apcmedia.com/salestools/ASTE-6Z7UZ8_R0_EN.pdf
I don't think the serial port does anything besides passing *levels*
to the monitoring PC. I.e., the "data" isn't the sort of "ASCII text"
that you might otherwise believe.
> I don't think there's much value to this thing, except maybe the big
> tranny which might make a good high current low voltage supply. Probably
> about 15 VCT at 30 amps or so.
>
> Are more modern UPS units made this way? Seems strange not to use high
> frequency magnetics to generate a 175 VDC rail and then use a bridge to
> generate the output waveform. And now that it's easy to make a PWM
> inverter with a high frequency carrier like a motor control, a fairly
> good sine wave could be made. And a crystal could be used to get a very
> accurate 50 or 60 Hz waveform, although it's usually not much needed
> except for an alarm clock. Actually, most computer equipment uses
> switching supplies and probably would operate just as well, if not
> better, with the straight DC rail (although perhaps at less than the 175
> volts).
>
> Any thoughts? Thanks.
These are typically "consumer kit" -- even the models marketed
for SOHO use. I inherit probably two a month from folks (usually
1000-1500 VA models) suffering from bad batteries ("Gee, it costs
as much to replace the batteries as I paid for the darn thing
to begin with!" or "Yikes! I just replaced the batteries a year
or two ago -- and we haven't had any power outages in that time...")
or blown FETs (I have three XS/RS 1200's with that problem, now).
For most folks, UPS's *sound* like a great idea! Likewise, various
"(data) backup devices". In practice, the novelty usually wears
off pretty quick. :> I have 6 deployed here, currently, and
they tend to be more of "outlet/receptacle multipliers" than
real UPS's. I suspect they have alarmed more times from battery
failure than from actual power outages. But, our power tends
to be pretty reliable (below grade service seems to make a
difference -- esp in the warm/dry environment). So, the most
annoying thing is brief "flickers" when something, somewhere
might be switching to cover a changing distribution load
(most of my machines will survive a 1 second "outage" without
even requiring a UPS).
I previously had a 5KW unit that proved impractical to use
(the size of a dishwasher). And, dangerous to work on (the
*120* VDC battery). Routing the conditioned power to various
loads meant a long "extension cord" (or, a dedicated circuit!).
Some of the more "professional" units offer a better mix of
features, output waveform quality, etc. (I was offered a large
unit -- the battery bank being effectively a 40U rack -- but
was smart enough to realize I could never afford to keep
replacing the slew of batteries it needed!)
I've also seen smaller units used as DOOR STOPS to take advantage
of their size and weight (the power cord serves as a convenient
"handle" to drag it to where you want/need it!)
On 3/30/2012 11:45 PM, P E Schoen wrote:
> I have an old UPS unit that I found in a trash pile at a Hamfest
> probably 5 or more years ago, and I figured I might be able to use it as
> a 12 VDC to 120 VAC inverter. So I opened it up, and removed the two 6V
> SLA batteries (which had cracked, probably from freezing). I had thought
> the weight of the unit (about 22 lb.) was from the batteries, but there
> is also a rather large (3.5" x 4" x 4") transformer which probably
> weighs at least 10 lb. I had expected a much smaller ferrite transformer
> such as found in most inverters.
>
> So I thought maybe it was used in such a way as to create a good
> waveform, but when I powered the unit with a 12V supply (1.08A), I found
> that it was a "modified sine wave" which was just a series of positive
> and negative pulses 175 V peak and 2.6 mSec wide with a period of 17.2
> mSec (57 Hz), and it has an overshoot at turn-off.
as a center tapped coil with FETs tugging alternately on one
side, then the other.
The "difference" between various VA models is the number of
FETs paralleled for each "side" of the coil.
> This indicates that
> it is not being driven by a true bridge but just a very simple PWM
> push-pull drive. I found two heat sinks, each of which have four TO-220
> devices, and I found a rectangular pulse train 11.5 volts and 3.6 mSec
> wide, so they must be MOSFETs.
>
> It has quite a large and complex PCB, with a 4" x 6" section having
> about 10 DIP ICs and associated components. No SMDs. The unit has a DB-9
> serial port for computer connection. The date on the PCB is 1997. There
> does not appear to be any sort of microprocessor or "smarts", and the
> only IC I did not recognize was an MF4CN-50 which is a low pass filter
> http://www.datasheetcatalog.org/datasheet/nationalsemiconductor/DS005064.PDF.
> So, what does the serial port connection do, and how does it do it? Here
> is the user manual:
> http://www.apcmedia.com/salestools/ASTE-6Z7UZ8_R0_EN.pdf
to the monitoring PC. I.e., the "data" isn't the sort of "ASCII text"
that you might otherwise believe.
> I don't think there's much value to this thing, except maybe the big
> tranny which might make a good high current low voltage supply. Probably
> about 15 VCT at 30 amps or so.
>
> Are more modern UPS units made this way? Seems strange not to use high
> frequency magnetics to generate a 175 VDC rail and then use a bridge to
> generate the output waveform. And now that it's easy to make a PWM
> inverter with a high frequency carrier like a motor control, a fairly
> good sine wave could be made. And a crystal could be used to get a very
> accurate 50 or 60 Hz waveform, although it's usually not much needed
> except for an alarm clock. Actually, most computer equipment uses
> switching supplies and probably would operate just as well, if not
> better, with the straight DC rail (although perhaps at less than the 175
> volts).
>
> Any thoughts? Thanks.
for SOHO use. I inherit probably two a month from folks (usually
1000-1500 VA models) suffering from bad batteries ("Gee, it costs
as much to replace the batteries as I paid for the darn thing
to begin with!" or "Yikes! I just replaced the batteries a year
or two ago -- and we haven't had any power outages in that time...")
or blown FETs (I have three XS/RS 1200's with that problem, now).
For most folks, UPS's *sound* like a great idea! Likewise, various
"(data) backup devices". In practice, the novelty usually wears
off pretty quick. :> I have 6 deployed here, currently, and
they tend to be more of "outlet/receptacle multipliers" than
real UPS's. I suspect they have alarmed more times from battery
failure than from actual power outages. But, our power tends
to be pretty reliable (below grade service seems to make a
difference -- esp in the warm/dry environment). So, the most
annoying thing is brief "flickers" when something, somewhere
might be switching to cover a changing distribution load
(most of my machines will survive a 1 second "outage" without
even requiring a UPS).
I previously had a 5KW unit that proved impractical to use
(the size of a dishwasher). And, dangerous to work on (the
*120* VDC battery). Routing the conditioned power to various
loads meant a long "extension cord" (or, a dedicated circuit!).
Some of the more "professional" units offer a better mix of
features, output waveform quality, etc. (I was offered a large
unit -- the battery bank being effectively a 40U rack -- but
was smart enough to realize I could never afford to keep
replacing the slew of batteries it needed!)
I've also seen smaller units used as DOOR STOPS to take advantage
of their size and weight (the power cord serves as a convenient
"handle" to drag it to where you want/need it!)
P E Schoen
Mar 31, 2012, 6:30:05 PM3/31/12
to
"Don Y" wrote in message news:jl7r49$as2$1...@speranza.aioe.org...
> Yes. It's not even a "stepped sine wave" -- think of the primary
> as a center tapped coil with FETs tugging alternately on one
> side, then the other.
> The "difference" between various VA models is the number of
> FETs paralleled for each "side" of the coil.
I suppose a normal load would clean up the waveform to some extent. The
"ringing" was at a very low frequency and probably a result of surge
suppression components on the 120 VAC side.
> I don't think the serial port does anything besides passing
> *levels* to the monitoring PC. I.e., the "data" isn't the sort
> of "ASCII text" that you might otherwise believe.
I figured that it simply uses one of the RTS, CTS, DTR, or DSR lines as a
power fail indicator, and the PC software does all the rest. It probably
doesn't have the ability to read the battery level or load or anything like
that. Just a signal to save open files and perform an orderly shut-down of
the computer.
That's probably all it's good for, IMHO. The surge protection components
might be useful, but more conveniently located in a power strip. Seems a
shame to throw away a functioning unit, but I use a laptop for all my
computing needs, and it has its own UPS in a fully charged battery that
allows about an hour of continued use after a power failure (and the screen
provides a nice emergency light so I can find my flashlight).
I went to the Timonium Hamfest today, hoping to find some inexpensive SLA
batteries, but didn't find any. I have a 17 A-H battery (date code 1999?) I
bought there at least 5 years ago. I had it in an old garden tractor for
several years, and I was amazed that it still had juice after being outside
and only recharged once a year or so. It still seems to be going strong.
My project is a small electric tractor that has a three phase motor, and I
plan to use a couple of 12V batteries and inverters to generate about 300
VDC which I'll use with a 2 HP VF motor control. I know the 17 A-H SLA is
really too small, but a pair of them should allow maybe 10 minutes run time
at 1 HP average. The best price I found on-line was $33 for 18 A-H SLA,
while I can get a regular lead-acid garden tractor starting battery for
about $30 with 200 CCA (probably 20-30 A-H), and a 100 A-H deep cycle
battery for $85.
Thanks,
Paul
> Yes. It's not even a "stepped sine wave" -- think of the primary
> as a center tapped coil with FETs tugging alternately on one
> side, then the other.
> The "difference" between various VA models is the number of
> FETs paralleled for each "side" of the coil.
"ringing" was at a very low frequency and probably a result of surge
suppression components on the 120 VAC side.
> I don't think the serial port does anything besides passing
> *levels* to the monitoring PC. I.e., the "data" isn't the sort
> of "ASCII text" that you might otherwise believe.
power fail indicator, and the PC software does all the rest. It probably
doesn't have the ability to read the battery level or load or anything like
that. Just a signal to save open files and perform an orderly shut-down of
the computer.
might be useful, but more conveniently located in a power strip. Seems a
shame to throw away a functioning unit, but I use a laptop for all my
computing needs, and it has its own UPS in a fully charged battery that
allows about an hour of continued use after a power failure (and the screen
provides a nice emergency light so I can find my flashlight).
I went to the Timonium Hamfest today, hoping to find some inexpensive SLA
batteries, but didn't find any. I have a 17 A-H battery (date code 1999?) I
bought there at least 5 years ago. I had it in an old garden tractor for
several years, and I was amazed that it still had juice after being outside
and only recharged once a year or so. It still seems to be going strong.
My project is a small electric tractor that has a three phase motor, and I
plan to use a couple of 12V batteries and inverters to generate about 300
VDC which I'll use with a 2 HP VF motor control. I know the 17 A-H SLA is
really too small, but a pair of them should allow maybe 10 minutes run time
at 1 HP average. The best price I found on-line was $33 for 18 A-H SLA,
while I can get a regular lead-acid garden tractor starting battery for
about $30 with 200 CCA (probably 20-30 A-H), and a 100 A-H deep cycle
battery for $85.
Thanks,
Paul
Phil Hobbs
Mar 31, 2012, 6:36:08 PM3/31/12
to
even had good batteries. One of them runs my NAS boxes at home, and the
other runs my office server, a 16-core AMD Magny Cours box running
64-bit CentOS 6.2. Clicking on the power icon brings up a window that
has all sorts of info about the UPS, including load levels, AC line
voltage and frequency, the battery's state of charge, and so on. So
there's a lot more info there than you suppose.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058
hobbs at electrooptical dot net
http://electrooptical.net
Don Y
Mar 31, 2012, 6:59:54 PM3/31/12
to
Hi Paul,
On 3/31/2012 3:30 PM, P E Schoen wrote:
> "Don Y" wrote in message news:jl7r49$as2$1...@speranza.aioe.org...
detailed reports on the status of batteries (including external
"add-on" packs), actual load seen by the UPS (depends on whether
you have an online or offline UPS), uptime estimates, programmable
alarm thresholds, support for multiple UPS's, integration within
the "management console", support for load shedding, event logging,
etc.
Of course, the features you get vary with the cost/size of the
UPS! :>
>> I've also seen smaller units used as DOOR STOPS to take
>> advantage of their size and weight (the power cord serves
>> as a convenient "handle" to drag it to where you want/need it!)
>
> That's probably all it's good for, IMHO. The surge protection components
> might be useful, but more conveniently located in a power strip. Seems a
> shame to throw away a functioning unit, but I use a laptop for all my
> computing needs, and it has its own UPS in a fully charged battery that
> allows about an hour of continued use after a power failure (and the
> screen provides a nice emergency light so I can find my flashlight).
I have small units on each of my switches, name server, etc.
I.e., things that need to work for anything to be able to
talk to anything else. Each workstation has a ~1000-1500
unit to keep the machine and displays "up" -- I don't worry
about printers (most of my printers have big power requirements)
or other little peripherals. A power interruption would just
be a "small inconvenience" for those ("Crap! I'll have to rescan
that photo/sheet" "Grrrr... that *plot* is now toast" etc.).
OTOH, the operations performed by the workstations tend to be
a bit more problematic to resume ("Hmmm... have to rerender that
3D animation").
But, the biggest advantage is having a single power switch for
each workstation+displays+core peripherals (motion controller,
tablet, etc.). Otherwise, I have to shut down each device
individually and/or turn off entire *benches*.
> I went to the Timonium Hamfest today, hoping to find some inexpensive
> SLA batteries, but didn't find any. I have a 17 A-H battery (date code
> 1999?) I bought there at least 5 years ago. I had it in an old garden
> tractor for several years, and I was amazed that it still had juice
> after being outside and only recharged once a year or so. It still seems
> to be going strong.
>
> My project is a small electric tractor that has a three phase motor, and
> I plan to use a couple of 12V batteries and inverters to generate about
> 300 VDC which I'll use with a 2 HP VF motor control. I know the 17 A-H
> SLA is really too small, but a pair of them should allow maybe 10
> minutes run time at 1 HP average. The best price I found on-line was $33
> for 18 A-H SLA, while I can get a regular lead-acid garden tractor
> starting battery for about $30 with 200 CCA (probably 20-30 A-H), and a
> 100 A-H deep cycle battery for $85.
Do you really intend that to be a *tractor*? (workhorse)
You can consider looking into the power plants in electric
"fork lifts". You'd have to change the gearing as they
tend to be designed for torque at the expense of speed...
If you just want a "toy" to cart you around, motors from
electric wheelchairs are a viable option (300-800W 24V).
These are often "discarded" when their owner passes away
or "insurance" opts to cover a replacement (possibly because
the user's needs have changed -- most chairs are "fitted"
to the needs of the user... eye tracking, head tracking,
joystick, etc.)
Good luck!
On 3/31/2012 3:30 PM, P E Schoen wrote:
> "Don Y" wrote in message news:jl7r49$as2$1...@speranza.aioe.org...
>> I don't think the serial port does anything besides passing
>> *levels* to the monitoring PC. I.e., the "data" isn't the sort
>> of "ASCII text" that you might otherwise believe.
>
> I figured that it simply uses one of the RTS, CTS, DTR, or DSR lines as
> a power fail indicator, and the PC software does all the rest. It
> probably doesn't have the ability to read the battery level or load or
> anything like that. Just a signal to save open files and perform an
> orderly shut-down of the computer.
Different models have different capabilities. Some provide more
>> *levels* to the monitoring PC. I.e., the "data" isn't the sort
>> of "ASCII text" that you might otherwise believe.
>
> I figured that it simply uses one of the RTS, CTS, DTR, or DSR lines as
> a power fail indicator, and the PC software does all the rest. It
> probably doesn't have the ability to read the battery level or load or
> anything like that. Just a signal to save open files and perform an
> orderly shut-down of the computer.
detailed reports on the status of batteries (including external
"add-on" packs), actual load seen by the UPS (depends on whether
you have an online or offline UPS), uptime estimates, programmable
alarm thresholds, support for multiple UPS's, integration within
the "management console", support for load shedding, event logging,
etc.
Of course, the features you get vary with the cost/size of the
UPS! :>
>> I've also seen smaller units used as DOOR STOPS to take
>> advantage of their size and weight (the power cord serves
>> as a convenient "handle" to drag it to where you want/need it!)
>
> That's probably all it's good for, IMHO. The surge protection components
> might be useful, but more conveniently located in a power strip. Seems a
> shame to throw away a functioning unit, but I use a laptop for all my
> computing needs, and it has its own UPS in a fully charged battery that
> allows about an hour of continued use after a power failure (and the
> screen provides a nice emergency light so I can find my flashlight).
I.e., things that need to work for anything to be able to
talk to anything else. Each workstation has a ~1000-1500
unit to keep the machine and displays "up" -- I don't worry
about printers (most of my printers have big power requirements)
or other little peripherals. A power interruption would just
be a "small inconvenience" for those ("Crap! I'll have to rescan
that photo/sheet" "Grrrr... that *plot* is now toast" etc.).
OTOH, the operations performed by the workstations tend to be
a bit more problematic to resume ("Hmmm... have to rerender that
3D animation").
But, the biggest advantage is having a single power switch for
each workstation+displays+core peripherals (motion controller,
tablet, etc.). Otherwise, I have to shut down each device
individually and/or turn off entire *benches*.
> I went to the Timonium Hamfest today, hoping to find some inexpensive
> SLA batteries, but didn't find any. I have a 17 A-H battery (date code
> 1999?) I bought there at least 5 years ago. I had it in an old garden
> tractor for several years, and I was amazed that it still had juice
> after being outside and only recharged once a year or so. It still seems
> to be going strong.
>
> My project is a small electric tractor that has a three phase motor, and
> I plan to use a couple of 12V batteries and inverters to generate about
> 300 VDC which I'll use with a 2 HP VF motor control. I know the 17 A-H
> SLA is really too small, but a pair of them should allow maybe 10
> minutes run time at 1 HP average. The best price I found on-line was $33
> for 18 A-H SLA, while I can get a regular lead-acid garden tractor
> starting battery for about $30 with 200 CCA (probably 20-30 A-H), and a
> 100 A-H deep cycle battery for $85.
You can consider looking into the power plants in electric
"fork lifts". You'd have to change the gearing as they
tend to be designed for torque at the expense of speed...
If you just want a "toy" to cart you around, motors from
electric wheelchairs are a viable option (300-800W 24V).
These are often "discarded" when their owner passes away
or "insurance" opts to cover a replacement (possibly because
the user's needs have changed -- most chairs are "fitted"
to the needs of the user... eye tracking, head tracking,
joystick, etc.)
Good luck!
miso
Mar 31, 2012, 7:37:47 PM3/31/12
to
Modified sine is so bad I would rather lose power.
I use a double conversion UPS. They convert the mains to DC where it is
easy to filter and cap load, then produce a true sine (I think 3% THD).
The advantage is there is no required time for the UPS to kick in. It is
always on. The disadvantage is it is always on. Thus you have cooling
fans and a bit of efficiency loss.
APC makes them, but you won't find them in consumer stores. I'm running
an Opti-UPS. Same basic idea.
The log catches a few glitches once in a while. I caught a few live
(heard the relay flip to kick in the battery) during a recent wind storm.
If you go double conversion, you need to inspect your load carefully.
This is a case where the UPS is actually working rather than just
sitting there.
Nico Coesel
Mar 31, 2012, 8:36:40 PM3/31/12
to
miso <mi...@sushi.com> wrote:
>
>Modified sine is so bad I would rather lose power.
>
>I use a double conversion UPS. They convert the mains to DC where it is
>easy to filter and cap load, then produce a true sine (I think 3% THD).
>The advantage is there is no required time for the UPS to kick in. It is
>always on. The disadvantage is it is always on. Thus you have cooling
>fans and a bit of efficiency loss.
I used to have a UPS like that. The degauss coil in my monitor killed
>
>Modified sine is so bad I would rather lose power.
>
>I use a double conversion UPS. They convert the mains to DC where it is
>easy to filter and cap load, then produce a true sine (I think 3% THD).
>The advantage is there is no required time for the UPS to kick in. It is
>always on. The disadvantage is it is always on. Thus you have cooling
>fans and a bit of efficiency loss.
it.
Don Y
Mar 31, 2012, 9:24:44 PM3/31/12
to
On 3/31/2012 4:37 PM, miso wrote:
>
> Modified sine is so bad I would rather lose power.
>
> I use a double conversion UPS. They convert the mains to DC where it is
> easy to filter and cap load, then produce a true sine (I think 3% THD).
These are often called "on-line" converters.
>
> Modified sine is so bad I would rather lose power.
>
> I use a double conversion UPS. They convert the mains to DC where it is
> easy to filter and cap load, then produce a true sine (I think 3% THD).
> The advantage is there is no required time for the UPS to kick in. It is
thrown on its output; the output operates at a constant line frequency;
etc.
If the load can't handle the switch-over time (typically O(10ms)),
then an offline UPS can prove to be useless -- the power to the
load disappears for that period of time even if the batteries, UPS,
etc. are "good".
> always on. The disadvantage is it is always on. Thus you have cooling
> fans and a bit of efficiency loss.
space -- because the converter is always carrying the load!
You also have a funky power factor that you present to the utility
since the UPS looks like a bridge feeding a large cap (big enough to
carry the load between AC cycles). For users (businesses) looking for
true uninterrupted power (e.g., with a diesel genset coming online
to restore power *to* the UPS) this can require the genset to be
needlessly (?) oversized.
Efficiency loss can hurt considerably since you have two nonideal
converters operating in cascade. The heat thrown off testifies to
the losses encountered. Normally, the input rectifier only processes
power to charge the batteries -- thereafter, sees no losses until
the batteries once again need charging (at which point, power is
presumably available and the inverter isn't running).
Of course, you can *buy* your way around these problems... :>
miso
Apr 1, 2012, 1:31:02 AM4/1/12
to
The other advantage of on-line is you get brown out protection. I still
prefer using the term double conversion because online has so many other
meanings. But you are correct in that most units are sold as online.
> http://www.opti-ups.com/index.asp?SCID=SC10090051
Well it claims PFC of 0.97 and efficiency of 92%. Of course at full
load, which isn't reality. All the computers it feeds are PFC corrected
and high efficiency.
The only thing I found kind of lame about the unit is the front panel is
plastic, which in turn snaps into the metal box. The fit is kind of loose.
Expensive, but it drives a few computers and a monitor. Not that
computers are all that expensive these days, but the hassle of getting
everything working again makes the on-line UPS worth the effort.
It also has a bypass mode, which to my understanding means it acts like
a conventional UPS, i.e. only turns on when needed, but supplies clean
power. I don't use it that way.
The APC and Opti units are made in China unfortunately. The reason I got
the Opti is it has an intelligent fan. You can hear it increase speed
when I turn on a PC due to the surge, then it drops in noise again. The
APC unit didn't have that feature. Note 40dB is mighty loud.
Similar Tripplite item. You can even get "hospital grade" versions.
> http://www.tripplite.com/en/products/model.cfm?txtSeriesID=745&txtModelID=2800
Getting reviews on these items it kind of tough since they are soho
grade. Data centers use bigger UPSs and consumers buy the junk modified
sine. Data centers sometimes use computers that take 48V input rather
than AC.
prefer using the term double conversion because online has so many other
meanings. But you are correct in that most units are sold as online.
> http://www.opti-ups.com/index.asp?SCID=SC10090051
Well it claims PFC of 0.97 and efficiency of 92%. Of course at full
load, which isn't reality. All the computers it feeds are PFC corrected
and high efficiency.
The only thing I found kind of lame about the unit is the front panel is
plastic, which in turn snaps into the metal box. The fit is kind of loose.
Expensive, but it drives a few computers and a monitor. Not that
computers are all that expensive these days, but the hassle of getting
everything working again makes the on-line UPS worth the effort.
It also has a bypass mode, which to my understanding means it acts like
a conventional UPS, i.e. only turns on when needed, but supplies clean
power. I don't use it that way.
The APC and Opti units are made in China unfortunately. The reason I got
the Opti is it has an intelligent fan. You can hear it increase speed
when I turn on a PC due to the surge, then it drops in noise again. The
APC unit didn't have that feature. Note 40dB is mighty loud.
Similar Tripplite item. You can even get "hospital grade" versions.
> http://www.tripplite.com/en/products/model.cfm?txtSeriesID=745&txtModelID=2800
Getting reviews on these items it kind of tough since they are soho
grade. Data centers use bigger UPSs and consumers buy the junk modified
sine. Data centers sometimes use computers that take 48V input rather
than AC.
Don Y
Apr 1, 2012, 1:50:51 AM4/1/12
to
On 3/31/2012 10:31 PM, miso wrote:
> The other advantage of on-line is you get brown out protection. I still
"Line interactive" designs offer some correction. And, FERRUPS.
> The other advantage of on-line is you get brown out protection. I still
> prefer using the term double conversion because online has so many other
> meanings. But you are correct in that most units are sold as online.
one that depended on your interpretation of "on" vs "off". I have
to *think* before refering to one or the other (it would be nice if
it was more intuitive)
> Well it claims PFC of 0.97 and efficiency of 92%. Of course at full
> load, which isn't reality. All the computers it feeds are PFC corrected
> and high efficiency.
>
> The only thing I found kind of lame about the unit is the front panel is
> plastic, which in turn snaps into the metal box. The fit is kind of loose.
for formed pieces)
> Expensive, but it drives a few computers and a monitor. Not that
> computers are all that expensive these days, but the hassle of getting
> everything working again makes the on-line UPS worth the effort.
your mains power. Here, the outages we've had number ~0.5 per year!
Unfortunately, some have been very lengthy (like when the neighborhood
distribution transformer burned up taking out power to ~100 homes.
They don't replace those things very quickly -- though they managed
to run a feed in from a neighboring circuit to bring some power
back).
OTOH, when I lived in Illinois, our neighborhood suffered 1-2 outages
per *month*.
> It also has a bypass mode, which to my understanding means it acts like
> a conventional UPS, i.e. only turns on when needed, but supplies clean
> power. I don't use it that way.
>
> The APC and Opti units are made in China unfortunately. The reason I got
> the Opti is it has an intelligent fan. You can hear it increase speed
> when I turn on a PC due to the surge, then it drops in noise again. The
> APC unit didn't have that feature. Note 40dB is mighty loud.
and self-adjust. Some will even alarm when the fan quits.
> Similar Tripplite item. You can even get "hospital grade" versions.
>> http://www.tripplite.com/en/products/model.cfm?txtSeriesID=745&txtModelID=2800
>
> Getting reviews on these items it kind of tough since they are soho
> grade. Data centers use bigger UPSs and consumers buy the junk modified
> sine. Data centers sometimes use computers that take 48V input rather
> than AC.
folks with a "UPS budget". Who plan on servicing them regularly,
etc. My attitude is that an outage is an opportunity to
"do something different". If I *really* need to keep working,
I can move to a laptop and power the modem from a UPS (almost
"forever" with the amount of power it requires).
A more *practical* use for the UPS's is to use them to power
CFL/LED lighting. The neighbors were all wondering why *we*
had power ("lights") while they didn't during the last outage.
<grin>
P E Schoen
Apr 5, 2012, 1:06:25 AM4/5/12
to
"Phil Hobbs" wrote in message news:4F7786D8...@electrooptical.net...
> I have a couple of APC BackUPS 750T's that I got from eBay. One
> of them even had good batteries. One of them runs my NAS boxes
> at home, and the other runs my office server, a 16-core AMD
> Magny Cours box running 64-bit CentOS 6.2. Clicking on the
> power icon brings up a window that has all sorts of info about
> the UPS, including load levels, AC line voltage and frequency,
> the battery's state of charge, and so on. So there's a lot more
> info there than you suppose.
Maybe the higher output units (or more recent models) have more
monitor/control features. I can't see how all that information can be passed
to the serial port without some sort of "smarts", like a microprocessor.
There seem to be maybe 4 transistors and a dozen resistors, and an
optoisolator, connected to the serial port connector. It seems there are 4
input pins other than RXD that might be used for some information, but it
would be essentially go/nogo. They are CD, DSR, CTS, and RI.
I was able to disconnect the gate drives for the two banks of MOSFETs, and I
hooked them to a PIC16F684 which has PWM output. I set it for 500 Hz, 100%
duty cycle, with about 2 uSec deadband, and I used an LM324 as a simple gate
driver to get 10-12V gate drive. The MOSFETs are IRFZ46 which are 50V, 50A,
24 mOhm. When I first tried it, I got 360V P-P with 11.8V in at 3.9A, but
something was heating up. I think it was the overvoltage / surge protection
components, and when I disconnected the secondary from the board, I got 360V
P-P at 1.47 amps, and no apparent heating. So I did some load testing:
1800 ohms 172V 4.10W 6.0V 1.22A 7.32W
1800 ohms 238V 7.86W 8.0V 1.58A 12.6W
1800 ohms 344V 16.4W 12.0V 2.82A 33.8W
300 ohms 171V 23.8W 6.0V 4.38A 26.3W
300 ohms 200V 33.3W 7.0V 5.00A 35.0W
For some reason the efficiency with a 300 ohm load seems a lot better than
with 1800 ohms. It may have something to do with the power supply going into
overcurrent limit, or maybe there is something about running it at 8 volts
or more. My next step will probably be to use a heavy duty supply or
directly from a battery, and I should be able to get 108 watts into the 300
ohm load. I have several of these resistors (91 watts each), so I can test
up to about 500 watts. I also have some finstrip heaters which are 26 ohms,
and that will give me 1246 watts if the voltage holds. The battery draw will
be about 100 amps at this point. So maybe I'll use two heaters in series for
600 watts and 50 amps from the battery.
Final test will be adding the FWB and capacitors to get 360 VDC which should
supply the VF drive for the motor. But I'm a bit worried about the start-up
current surges into the capacitors, especially with a square wave. I'm
considering making a current limiter, but at such high currents there may be
unacceptable losses. Best thing might be to use a 100A 100mV shunt and have
that connected to the PIC. The A/D converter might be fast enough, but
otherwise the comparator may be the better choice, and it could shut down
the PWM drive. The Back-UPS has two 40 amp fuses in parallel, but I don't
want to rely on them except for ultimate fail-safe protection. The
simulation shows 566 amps RMS during start-up and 84 amps RMS once the
output has stabilized at 20V into 104 ohms and 757 watts.
Maybe I'll have more results in a day or two.
Paul
> I have a couple of APC BackUPS 750T's that I got from eBay. One
> of them even had good batteries. One of them runs my NAS boxes
> at home, and the other runs my office server, a 16-core AMD
> Magny Cours box running 64-bit CentOS 6.2. Clicking on the
> power icon brings up a window that has all sorts of info about
> the UPS, including load levels, AC line voltage and frequency,
> the battery's state of charge, and so on. So there's a lot more
> info there than you suppose.
monitor/control features. I can't see how all that information can be passed
to the serial port without some sort of "smarts", like a microprocessor.
There seem to be maybe 4 transistors and a dozen resistors, and an
optoisolator, connected to the serial port connector. It seems there are 4
input pins other than RXD that might be used for some information, but it
would be essentially go/nogo. They are CD, DSR, CTS, and RI.
I was able to disconnect the gate drives for the two banks of MOSFETs, and I
hooked them to a PIC16F684 which has PWM output. I set it for 500 Hz, 100%
duty cycle, with about 2 uSec deadband, and I used an LM324 as a simple gate
driver to get 10-12V gate drive. The MOSFETs are IRFZ46 which are 50V, 50A,
24 mOhm. When I first tried it, I got 360V P-P with 11.8V in at 3.9A, but
something was heating up. I think it was the overvoltage / surge protection
components, and when I disconnected the secondary from the board, I got 360V
P-P at 1.47 amps, and no apparent heating. So I did some load testing:
1800 ohms 172V 4.10W 6.0V 1.22A 7.32W
1800 ohms 238V 7.86W 8.0V 1.58A 12.6W
1800 ohms 344V 16.4W 12.0V 2.82A 33.8W
300 ohms 171V 23.8W 6.0V 4.38A 26.3W
300 ohms 200V 33.3W 7.0V 5.00A 35.0W
For some reason the efficiency with a 300 ohm load seems a lot better than
with 1800 ohms. It may have something to do with the power supply going into
overcurrent limit, or maybe there is something about running it at 8 volts
or more. My next step will probably be to use a heavy duty supply or
directly from a battery, and I should be able to get 108 watts into the 300
ohm load. I have several of these resistors (91 watts each), so I can test
up to about 500 watts. I also have some finstrip heaters which are 26 ohms,
and that will give me 1246 watts if the voltage holds. The battery draw will
be about 100 amps at this point. So maybe I'll use two heaters in series for
600 watts and 50 amps from the battery.
Final test will be adding the FWB and capacitors to get 360 VDC which should
supply the VF drive for the motor. But I'm a bit worried about the start-up
current surges into the capacitors, especially with a square wave. I'm
considering making a current limiter, but at such high currents there may be
unacceptable losses. Best thing might be to use a 100A 100mV shunt and have
that connected to the PIC. The A/D converter might be fast enough, but
otherwise the comparator may be the better choice, and it could shut down
the PWM drive. The Back-UPS has two 40 amp fuses in parallel, but I don't
want to rely on them except for ultimate fail-safe protection. The
simulation shows 566 amps RMS during start-up and 84 amps RMS once the
output has stabilized at 20V into 104 ohms and 757 watts.
Maybe I'll have more results in a day or two.
Paul
P E Schoen
Apr 5, 2012, 4:04:25 AM4/5/12
to
I just tried reading input current at various supply voltages. Seems like it
is starting to saturate, but unexpected at 500 Hz. Maybe it's because of
core losses, since this is an ordinary E-I transformer and not a toroid as I
previously used.
6V 0.57A
7V 0.63A
8V 0.69A
9V 0.77A
10V 0.92A
11V 1.09A
12V 1.44A 360V p-p
13V 1.93A
For the toroid, I measured:
6V 0.93A 151V p-p
7V 1.03A 172V p-p
8V 1.15A 192V p-p
9V 1.30A 220V p-p
10V 1.43A 241V p-p
11V 1.59A 263V p-p
12V 1.80A 289V p-p
13V 2.03A 309V p-p
The toroid current is just about linear with voltage, but for the E-I
tranny, the current at 13V is more than three times that at 6.5V. Any ideas
about why this is?
Paul
is starting to saturate, but unexpected at 500 Hz. Maybe it's because of
core losses, since this is an ordinary E-I transformer and not a toroid as I
previously used.
6V 0.57A
7V 0.63A
8V 0.69A
9V 0.77A
10V 0.92A
11V 1.09A
12V 1.44A 360V p-p
13V 1.93A
For the toroid, I measured:
6V 0.93A 151V p-p
7V 1.03A 172V p-p
8V 1.15A 192V p-p
9V 1.30A 220V p-p
10V 1.43A 241V p-p
11V 1.59A 263V p-p
12V 1.80A 289V p-p
13V 2.03A 309V p-p
The toroid current is just about linear with voltage, but for the E-I
tranny, the current at 13V is more than three times that at 6.5V. Any ideas
about why this is?
Paul
miso
Apr 5, 2012, 2:05:20 PM4/5/12
to
I'm not concerned about down time as much as data loss. The UPS is set
up to shut down the computers.
up to shut down the computers.
Sjouke Burry
Apr 5, 2012, 7:16:32 PM4/5/12
to
P E Schoen
Apr 5, 2012, 9:49:33 PM4/5/12
to
"Sjouke Burry" wrote in message
news:XnsA02DD86D1679sj...@213.75.12.10...
It has the characteristics of core saturation, but this is at the rated
voltage for the transformer (12 V peak rectangular wave), and at 500 Hz,
which is more than 8 times its rated frequency of 60 Hz. The output voltage
is a pretty good square wave, with no visible droop, which might be expected
at saturation (although the regulated supply might hold it steady even if
current is sharply increasing).
But there is a slight difference in the output waveforms. The E-I
transformer shows a more or less smooth transition from the positive to the
negative peak, while the toroid shows a faster drop to zero, then a brief
period of off time, and then another rapid rise to the opposite peak. I
think my driver has a 2 uSec deadband, and if the transition is linear
during this time, rather than stepped as seen in the toroid, there is
probably considerable power dissipated during that time. I should really
measure the current waveform, but if there is core loss due to switching, it
would show up as additional power dissipation.
It is still within acceptable limits for an inverter rated at 600 VA,
however. I could also change the frequency to 100 Hz or 60 Hz to see if the
power is reduced. I like the idea of a higher frequency so I can get less
ripple for the same size capacitors.
Paul
news:XnsA02DD86D1679sj...@213.75.12.10...
>> The toroid current is just about linear with voltage, but for the
>> E-I tranny, the current at 13V is more than three times that
>> at 6.5V. Any ideas about why this is?
> Core saturation?
>> E-I tranny, the current at 13V is more than three times that
>> at 6.5V. Any ideas about why this is?
It has the characteristics of core saturation, but this is at the rated
voltage for the transformer (12 V peak rectangular wave), and at 500 Hz,
which is more than 8 times its rated frequency of 60 Hz. The output voltage
is a pretty good square wave, with no visible droop, which might be expected
at saturation (although the regulated supply might hold it steady even if
current is sharply increasing).
But there is a slight difference in the output waveforms. The E-I
transformer shows a more or less smooth transition from the positive to the
negative peak, while the toroid shows a faster drop to zero, then a brief
period of off time, and then another rapid rise to the opposite peak. I
think my driver has a 2 uSec deadband, and if the transition is linear
during this time, rather than stepped as seen in the toroid, there is
probably considerable power dissipated during that time. I should really
measure the current waveform, but if there is core loss due to switching, it
would show up as additional power dissipation.
It is still within acceptable limits for an inverter rated at 600 VA,
however. I could also change the frequency to 100 Hz or 60 Hz to see if the
power is reduced. I like the idea of a higher frequency so I can get less
ripple for the same size capacitors.
Paul
notbob
Apr 5, 2012, 11:47:32 PM4/5/12
to
On 2012-04-06, P E Schoen <pa...@peschoen.com> wrote:
> It has the characteristics of core saturation, but this is at the rated
> voltage for the transformer (12 V peak rectangular wave), and at 500 Hz,
> which is more than 8 times its rated frequency of 60 Hz. The output voltage
> is a pretty good square wave, with no visible droop, which might be expected
> at saturation (although the regulated supply might hold it steady even if
> current is sharply increasing).
LOL!....
> It has the characteristics of core saturation, but this is at the rated
> voltage for the transformer (12 V peak rectangular wave), and at 500 Hz,
> which is more than 8 times its rated frequency of 60 Hz. The output voltage
> is a pretty good square wave, with no visible droop, which might be expected
> at saturation (although the regulated supply might hold it steady even if
> current is sharply increasing).
Reading all the posts in this thread is like listening to a buncha old
druids arguing about the merits of some twig/animal/leaf/star/tree and
how they should worship it.
Don't get me wrong, as an old geezer who's played an electrified
stringed instrument for over 50 yrs and am only now, as a hobbyist,
learning about electronics and tubes and such, I'm sure I'll go to my
grave jes as whacked out as the rest of you "experts", and laughing my
ass off about it all. ;)
nb
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