• Inverters vs wallwarts

    From bob prohaska@21:1/5 to All on Sat Jun 25 02:10:59 2022
    I'm setting up a UPS for my computer/comms equipment using an
    inverter/charger and battery from Amazon. The equipment draw
    is only about 40 watts measured with a Kill-A-Watt, but all
    the associated wallwarts use capacitive-input switching power
    supplies. That means they only draw current at line peaks.

    My seat-of-the-pants guess is that the duty cycle is around 10%,
    meaning that the average 40 watts is really 400 watts 10% of the time.
    That's well within the continuous power rating of the inverter, which
    is 800 watts, so it's likely the setup will work as it is.

    The question is: Can the peak load be made closer to the average
    load by putting an inductor in the AC line feeding the wallwarts?

    If anybody's been through this exercise I'd be grateful for guidance.

    Thanks for reading,

    bob prohaska

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Allison@21:1/5 to bob prohaska on Fri Jun 24 19:26:21 2022
    bob prohaska wrote:
    ================

    I'm setting up a UPS for my computer/comms equipment using an inverter/charger and battery from Amazon. The equipment draw
    is only about 40 watts measured with a Kill-A-Watt, but all
    the associated wallwarts use capacitive-input switching power
    supplies. That means they only draw current at line peaks.

    My seat-of-the-pants guess is that the duty cycle is around 10%,
    meaning that the average 40 watts is really 400 watts 10% of the time.
    That's well within the continuous power rating of the inverter, which
    is 800 watts, so it's likely the setup will work as it is.

    The question is: Can the peak load be made closer to the average
    load by putting an inductor in the AC line feeding the wallwarts?

    ** A well chosen choke will do that, but not by much.

    If anybody's been through this exercise I'd be grateful for guidance.

    ** PFC corrected SMPSs were invented for this job.
    Doubt if you will find such in wall warts.



    ...... Phil

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to bp@www.zefox.net on Fri Jun 24 19:15:34 2022
    On Sat, 25 Jun 2022 02:10:59 -0000 (UTC), bob prohaska
    <bp@www.zefox.net> wrote:

    I'm setting up a UPS for my computer/comms equipment using an >inverter/charger and battery from Amazon. The equipment draw
    is only about 40 watts measured with a Kill-A-Watt, but all
    the associated wallwarts use capacitive-input switching power
    supplies. That means they only draw current at line peaks.

    My seat-of-the-pants guess is that the duty cycle is around 10%,
    meaning that the average 40 watts is really 400 watts 10% of the time.
    That's well within the continuous power rating of the inverter, which
    is 800 watts, so it's likely the setup will work as it is.

    The question is: Can the peak load be made closer to the average
    load by putting an inductor in the AC line feeding the wallwarts?

    If anybody's been through this exercise I'd be grateful for guidance.

    Thanks for reading,

    bob prohaska



    You could scope the input current. It may not peak as high as you have estimated.



    --

    Anybody can count to one.

    - Robert Widlar

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Allison@21:1/5 to jla...@highlandsniptechnology.com on Fri Jun 24 19:52:53 2022
    On Saturday, June 25, 2022 at 12:15:48 PM UTC+10, jla...@highlandsniptechnology.com wrote:
    On Sat, 25 Jun 2022 02:10:59 -0000 (UTC), bob prohaska
    <b...@www.zefox.net> wrote:

    I'm setting up a UPS for my computer/comms equipment using an >inverter/charger and battery from Amazon. The equipment draw
    is only about 40 watts measured with a Kill-A-Watt, but all
    the associated wallwarts use capacitive-input switching power
    supplies. That means they only draw current at line peaks.

    My seat-of-the-pants guess is that the duty cycle is around 10%,
    meaning that the average 40 watts is really 400 watts 10% of the time. >That's well within the continuous power rating of the inverter, which
    is 800 watts, so it's likely the setup will work as it is.

    The question is: Can the peak load be made closer to the average
    load by putting an inductor in the AC line feeding the wallwarts?

    If anybody's been through this exercise I'd be grateful for guidance.

    Thanks for reading,

    bob prohaska


    You could scope the input current. It may not peak as high as you have estimated.

    ** Yeah, it more like 20 to 25% .

    With 50Hz power, 100Hz current pulses are about 2mS duration.



    ..... Phil

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Don Y@21:1/5 to bob prohaska on Fri Jun 24 20:04:03 2022
    On 6/24/2022 7:10 PM, bob prohaska wrote:
    I'm setting up a UPS for my computer/comms equipment using an inverter/charger and battery from Amazon. The equipment draw
    is only about 40 watts measured with a Kill-A-Watt, but all
    the associated wallwarts use capacitive-input switching power
    supplies. That means they only draw current at line peaks.

    My seat-of-the-pants guess is that the duty cycle is around 10%,
    meaning that the average 40 watts is really 400 watts 10% of the time.
    That's well within the continuous power rating of the inverter, which
    is 800 watts, so it's likely the setup will work as it is.

    The question is: Can the peak load be made closer to the average
    load by putting an inductor in the AC line feeding the wallwarts?

    If anybody's been through this exercise I'd be grateful for guidance.

    What are the *final* load voltages? E.g., a more efficient
    design may skip the mains voltage and convert direct to
    your actual load voltages E.g., I run a straight 48VDC supply
    instead of UPS->mains->48VDC -- because my loads are 48VDC powered.
    You might be able to just power your loads directly off a well
    chosen battery voltage (and simply *charge* it from the mains)

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to pallison49@gmail.com on Fri Jun 24 20:11:41 2022
    On Fri, 24 Jun 2022 19:52:53 -0700 (PDT), Phil Allison
    <pallison49@gmail.com> wrote:

    On Saturday, June 25, 2022 at 12:15:48 PM UTC+10, jla...@highlandsniptechnology.com wrote:
    On Sat, 25 Jun 2022 02:10:59 -0000 (UTC), bob prohaska
    <b...@www.zefox.net> wrote:

    I'm setting up a UPS for my computer/comms equipment using an
    inverter/charger and battery from Amazon. The equipment draw
    is only about 40 watts measured with a Kill-A-Watt, but all
    the associated wallwarts use capacitive-input switching power
    supplies. That means they only draw current at line peaks.

    My seat-of-the-pants guess is that the duty cycle is around 10%,
    meaning that the average 40 watts is really 400 watts 10% of the time.
    That's well within the continuous power rating of the inverter, which
    is 800 watts, so it's likely the setup will work as it is.

    The question is: Can the peak load be made closer to the average
    load by putting an inductor in the AC line feeding the wallwarts?

    If anybody's been through this exercise I'd be grateful for guidance.

    Thanks for reading,

    bob prohaska


    You could scope the input current. It may not peak as high as you have
    estimated.

    ** Yeah, it more like 20 to 25% .

    With 50Hz power, 100Hz current pulses are about 2mS duration.



    ..... Phil

    Big supplies are now required to be PFC, namely not pull big current
    spikes. Small warts may be exempt.

    Even with a simple rectifier front-end, the top of a sine wave is
    pretty soft. And it wouldn't shock me if some people skimp on caps.

    It's not hard to measure. Or just plug it into the converter and not
    worry. An 800 watt converter probably won't notice a 40 watt wart.



    --

    Anybody can count to one.

    - Robert Widlar

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jasen Betts@21:1/5 to bob prohaska on Sat Jun 25 04:13:55 2022
    On 2022-06-25, bob prohaska <bp@www.zefox.net> wrote:
    I'm setting up a UPS for my computer/comms equipment using an inverter/charger and battery from Amazon. The equipment draw
    is only about 40 watts measured with a Kill-A-Watt, but all
    the associated wallwarts use capacitive-input switching power
    supplies. That means they only draw current at line peaks.

    My seat-of-the-pants guess is that the duty cycle is around 10%,
    meaning that the average 40 watts is really 400 watts 10% of the time.
    That's well within the continuous power rating of the inverter, which
    is 800 watts, so it's likely the setup will work as it is.

    The question is: Can the peak load be made closer to the average
    load by putting an inductor in the AC line feeding the wallwarts?

    Yes but only a little, the current phase angle is typically only
    about 20 degrees leading so a line reactor will not help much. Most
    of the power factor comes from crest factor rather than cos(phi).

    It will work better if you put a bridge rectifier before the inductor.
    (because now you can use a larger inductor), but now you'll have to
    figure out which wall warts actually need AC, and only connect the
    DC-capable ones.

    --
    Jasen.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to prohaska on Sat Jun 25 05:07:07 2022
    On a sunny day (Sat, 25 Jun 2022 02:10:59 -0000 (UTC)) it happened bob
    prohaska <bp@www.zefox.net> wrote in <t95qrj$r99$1@dont-email.me>:

    I'm setting up a UPS for my computer/comms equipment using an >inverter/charger and battery from Amazon. The equipment draw
    is only about 40 watts measured with a Kill-A-Watt, but all
    the associated wallwarts use capacitive-input switching power
    supplies. That means they only draw current at line peaks.

    My seat-of-the-pants guess is that the duty cycle is around 10%,
    meaning that the average 40 watts is really 400 watts 10% of the time.
    That's well within the continuous power rating of the inverter, which
    is 800 watts, so it's likely the setup will work as it is.

    The question is: Can the peak load be made closer to the average
    load by putting an inductor in the AC line feeding the wallwarts?

    If anybody's been through this exercise I'd be grateful for guidance.

    Thanks for reading,

    bob prohaska

    Interesting question, my cheap UPS seems to put out a square wave
    I wondered if the flat tops are actually not better for the wall warts
    as the charging part is longer than with a sine wave top...
    Been working now fine for a year or so with this thing,
    comes in almost every day these days with mains company fiddling,..
    flashing light bulbs sometimes here too.
    To backup for longer times I have a pure sine wave 2 kW converter and a 250 Ah lifepo4 battery..
    So I can keep watching sat TV or even cook food.
    More than 10 wallwarts on that UPS now, some Raspberry Pi, some USB hubs, some cameras., also
    security recorder, monitors... .. audio amp... 4 TB harddisks...
    I would personally not bother with a a series inductor...

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Doe@21:1/5 to Jan Panteltje on Sat Jun 25 05:24:34 2022
    Jan Panteltje <pNaonStpealmtje@yahoo.com> wrote:

    bob prohaska wrote:

    I'm setting up a UPS for my computer/comms equipment using an >>inverter/charger and battery from Amazon. The equipment draw is only
    about 40 watts measured with a Kill-A-Watt, but all the associated >>wallwarts use capacitive-input switching power supplies. That means
    they only draw current at line peaks.

    My seat-of-the-pants guess is that the duty cycle is around 10%, meaning >>that the average 40 watts is really 400 watts 10% of the time. That's
    well within the continuous power rating of the inverter, which is 800 >>watts, so it's likely the setup will work as it is.

    The question is: Can the peak load be made closer to the average load by >>putting an inductor in the AC line feeding the wallwarts?

    If anybody's been through this exercise I'd be grateful for guidance.

    Interesting question, my cheap UPS seems to put out a square wave I
    wondered if the flat tops are actually not better for the wall warts as
    the charging part is longer than with a sine wave top... Been working
    now fine for a year or so with this thing, comes in almost every day
    these days with mains company fiddling,.. flashing light bulbs sometimes
    here too. To backup for longer times I have a pure sine wave 2 kW
    converter and a 250 Ah lifepo4 battery.. So I can keep watching sat TV
    or even cook food. More than 10 wallwarts on that UPS now, some
    Raspberry Pi, some USB hubs, some cameras., also security recorder, monitors... .. audio amp... 4 TB harddisks... I would personally not
    bother with a a series inductor...

    For a personal computer only... I use a Tripp-Lite LC1200. No battery at
    all. I don't recall the last time we had a power failure that lasted more
    than an moment. But there has been flickering. The line conditioner works
    great for momentary outages, no messing with a battery.

    Of course that doesn't suit everybody.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Allison@21:1/5 to Jan Panteltje on Fri Jun 24 22:37:26 2022
    Jan Panteltje wrote:
    ------------------------------------

    Interesting question, my cheap UPS seems to put out a square wave


    ** So when rectified is pure DC.

    I wondered if the flat tops are actually not better for the wall warts

    ** See above.


    ...... Phil

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From legg@21:1/5 to bp@www.zefox.net on Sat Jun 25 07:32:27 2022
    On Sat, 25 Jun 2022 02:10:59 -0000 (UTC), bob prohaska
    <bp@www.zefox.net> wrote:

    I'm setting up a UPS for my computer/comms equipment using an >inverter/charger and battery from Amazon. The equipment draw
    is only about 40 watts measured with a Kill-A-Watt, but all
    the associated wallwarts use capacitive-input switching power
    supplies. That means they only draw current at line peaks.

    My seat-of-the-pants guess is that the duty cycle is around 10%,
    meaning that the average 40 watts is really 400 watts 10% of the time.
    That's well within the continuous power rating of the inverter, which
    is 800 watts, so it's likely the setup will work as it is.

    The question is: Can the peak load be made closer to the average
    load by putting an inductor in the AC line feeding the wallwarts?

    If anybody's been through this exercise I'd be grateful for guidance.

    Thanks for reading,

    bob prohaska



    I did some passive correction for off-the-shelf 60Hz linears in
    the 80s. Best effects achieved using a saturable choke and
    quasi-resonant capacitor, over a limited range of power levels
    for any specific installation.

    The parts are generally impractical for a hobbyist to get
    ahold of, though restacking laminations from unvarnished scrap
    is possible. Requires good VP Impregnation to silence the
    final iteration.

    The actual current phase angle shifted from leading to lagging
    over the useful range. Output voltage into the 60Hz capacitive
    load was flat-topped, affecting the low-line voltage performance.
    The choke/cap combination supported the output difference
    during line current reversal.

    It's no good guessing what the current waveshape is; you've
    got to measure it / scope it. Line current transformers are
    pretty cheap these days, often included in <$10 wattmeters
    from off-shore sources. A scope is useful, but more expensive.

    A lot of modern wall-warts are actually PFC compliant, through
    the use of dedicated low power integrated controllers. These
    employ valley-fill or critical-conduction (FM) off-line switchers
    economically, at power levels as low as 5W.

    Don't guess. Measure. Read specs of devices involved.

    Don't go overboard. Your UPS output may be more tolerant of peak
    loads than you assume, and your loads may be less peaky, simply
    due to industry commodity trends and available parts.

    RL

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Anthony William Sloman@21:1/5 to Don Y on Sat Jun 25 05:31:36 2022
    On Saturday, June 25, 2022 at 5:04:19 AM UTC+2, Don Y wrote:
    On 6/24/2022 7:10 PM, bob prohaska wrote:
    I'm setting up a UPS for my computer/comms equipment using an inverter/charger and battery from Amazon. The equipment draw
    is only about 40 watts measured with a Kill-A-Watt, but all
    the associated wallwarts use capacitive-input switching power
    supplies. That means they only draw current at line peaks.

    My seat-of-the-pants guess is that the duty cycle is around 10%,
    meaning that the average 40 watts is really 400 watts 10% of the time. That's well within the continuous power rating of the inverter, which
    is 800 watts, so it's likely the setup will work as it is.

    The question is: Can the peak load be made closer to the average
    load by putting an inductor in the AC line feeding the wallwarts?

    If anybody's been through this exercise I'd be grateful for guidance.

    You can actually make some very strange inverters

    https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=1062238

    from 1983 talks about doing some interesting stuff. Buying two transformers rather than just one back then made the whole approach too expensive to be interesting. It might be worth looking again while thinking about printed windings.

    --
    Bill Sloman, Sydney

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From whit3rd@21:1/5 to Jasen Betts on Sat Jun 25 09:16:35 2022
    On Friday, June 24, 2022 at 9:31:00 PM UTC-7, Jasen Betts wrote:
    On 2022-06-25, bob prohaska <b...@www.zefox.net> wrote:

    The question is: Can the peak load be made closer to the average
    load by putting an inductor in the AC line feeding the wallwarts?

    Yes but only a little, the current phase angle is typically only
    about 20 degrees leading so a line reactor will not help much. Most
    of the power factor comes from crest factor rather than cos(phi).

    It will work better if you put a bridge rectifier before the inductor. (because now you can use a larger inductor), but now you'll have to
    figure out which wall warts actually need AC, and only connect the
    DC-capable ones.

    The inductor coming after the rectifier, though, means it has to handle the DC current without saturating; that can be a problem, and it does add weight
    and cost. Doing such a design is a tricky task, not easy to simulate or calculate, so is usually a cut-and-try exercise.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From whit3rd@21:1/5 to bill....@ieee.org on Sat Jun 25 09:16:04 2022
    On Saturday, June 25, 2022 at 5:31:43 AM UTC-7, bill....@ieee.org wrote:

    On 6/24/2022 7:10 PM, bob prohaska wrote:

    The question is: Can the peak load be made closer to the average
    load by putting an inductor in the AC line feeding the wallwarts?

    If anybody's been through this exercise I'd be grateful for guidance.

    You can actually make some very strange inverters

    https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=1062238

    from 1983 talks about doing some interesting stuff. Buying two transformers rather than just one back then made the whole approach too expensive to be interesting. It might be worth looking again while thinking about printed windings.

    Oh, the time for that HAS come, this is one of the results:

    <https://www.ti.com/lit/ds/symlink/ucc12050.pdf>

    Good for a half watt, and kinda... tiny. The actual info on the circuit design is sketchy, because
    there's not a lot of good symbols available to describe an integrated magnetcs circuit.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From bob prohaska@21:1/5 to Jan Panteltje on Sat Jun 25 18:55:59 2022
    Jan Panteltje <pNaonStpealmtje@yahoo.com> wrote:
    On a sunny day (Sat, 25 Jun 2022 02:10:59 -0000 (UTC)) it happened bob prohaska <bp@www.zefox.net> wrote in <t95qrj$r99$1@dont-email.me>:

    I'm setting up a UPS for my computer/comms equipment using an >>inverter/charger and battery from Amazon. The equipment draw
    is only about 40 watts measured with a Kill-A-Watt, but all
    the associated wallwarts use capacitive-input switching power
    supplies. That means they only draw current at line peaks.

    [snip]
    The question is: Can the peak load be made closer to the average
    load by putting an inductor in the AC line feeding the wallwarts?


    Interesting question, my cheap UPS seems to put out a square wave
    I wondered if the flat tops are actually not better for the wall warts
    as the charging part is longer than with a sine wave top...

    AIUI, current into a capacitor is dv/dt x C, so the square wave should
    be much worse in terms of peak current than my sine-wave case. Charging
    is completed before the flat top of the cycle can commence. Seems likely
    the leakage inductance of the inverter's transformer is dominant.

    Been working now fine for a year or so with this thing,
    comes in almost every day these days with mains company fiddling,..
    flashing light bulbs sometimes here too.
    To backup for longer times I have a pure sine wave 2 kW converter and a 250 Ah lifepo4 battery..
    So I can keep watching sat TV or even cook food.
    More than 10 wallwarts on that UPS now, some Raspberry Pi, some USB hubs, some cameras., also
    security recorder, monitors... .. audio amp... 4 TB harddisks...
    I would personally not bother with a a series inductor...


    Your use case sounds very close to mine. If you aren't having trouble it
    seems doubtful I will.

    Thanks for writing,

    bob prohaska

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jasen Betts@21:1/5 to whit3rd@gmail.com on Sat Jun 25 21:18:18 2022
    On 2022-06-25, whit3rd <whit3rd@gmail.com> wrote:
    On Friday, June 24, 2022 at 9:31:00 PM UTC-7, Jasen Betts wrote:
    On 2022-06-25, bob prohaska <b...@www.zefox.net> wrote:

    The question is: Can the peak load be made closer to the average
    load by putting an inductor in the AC line feeding the wallwarts?

    Yes but only a little, the current phase angle is typically only
    about 20 degrees leading so a line reactor will not help much. Most
    of the power factor comes from crest factor rather than cos(phi).

    It will work better if you put a bridge rectifier before the inductor.
    (because now you can use a larger inductor), but now you'll have to
    figure out which wall warts actually need AC, and only connect the
    DC-capable ones.

    The inductor coming after the rectifier, though, means it has to handle the DC
    current without saturating; that can be a problem, and it does add weight and cost.

    The current magnitude is the same as the ac current magnitude,
    so not much of a problem. What bad thing happens if it saturates?

    Doing such a design is a tricky task, not easy to simulate or
    calculate, so is usually a cut-and-try exercise.

    Last time I looked at it in detail, it seemed pretty easy to hit the
    ballpark.

    The aim is not a resonant filter, it's just making a current reservoir
    so that (more) continuous current is drawn from the supply instead of spikes
    on the peaks of the sine wave (or the edges of a modified square wave
    inverter output)

    --
    Jasen.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Allison@21:1/5 to bob prohaska on Sat Jun 25 15:10:32 2022
    bob prohaska wrote:
    ======================

    AIUI, current into a capacitor is dv/dt x C, so the square wave should
    be much worse in terms of peak current than my sine-wave case.

    ** Nope - a rectified square wave is pure DC.
    SMPSs used in pro-audio power amps are nearly all square wave inverters.

    Battery to AC inverters are different.


    ..... Phil

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From whit3rd@21:1/5 to palli...@gmail.com on Sat Jun 25 20:22:46 2022
    On Saturday, June 25, 2022 at 3:10:38 PM UTC-7, palli...@gmail.com wrote:
    bob prohaska wrote:

    AIUI, current into a capacitor is dv/dt x C, so the square wave should
    be much worse in terms of peak current than my sine-wave case.

    ** Nope - a rectified square wave is pure DC.
    SMPSs used in pro-audio power amps are nearly all square wave inverters.

    If the load on an AC source were a capacitor, you'd get
    current= dv/dt x C, and if the load were a rectifier into a (capacitor in parallel with a resistor)
    you'd get something more benign. In a power brick, the load is a rectifier and (resistor-loaded?)
    regulator, like a capacitor in parallel with a current sink.

    The ramp up when the rectifier diodes turn on will be abrupt, lots of peak current,
    which was what the inductor was intended to moderate.

    If the hypothetical inductor saturates, it'll make a buzzing sound; that's annoying.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Allison@21:1/5 to All on Sun Jun 26 00:45:38 2022
    WITLESS whit3rd wrote:
    =================

    AIUI, current into a capacitor is dv/dt x C, so the square wave should
    be much worse in terms of peak current than my sine-wave case.

    ** Nope - a rectified square wave is pure DC.
    SMPSs used in pro-audio power amps are nearly all square wave inverters.
    If the load on an AC source were a capacitor, you'd get
    current= dv/dt x C, and if the load were a rectifier into a (capacitor in parallel with a resistor)
    you'd get something more benign. In a power brick, the load is a rectifier and (resistor-loaded?)
    regulator, like a capacitor in parallel with a current sink.

    The ramp up when the rectifier diodes turn on will be abrupt, lots of peak current,
    which was what the inductor was intended to moderate.

    If the hypothetical inductor saturates, it'll make a buzzing sound; that's annoying.


    ** Context and relevance are not to be found in this fool's dictionary.


    .... Phil

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to whit3rd@gmail.com on Sun Jun 26 09:23:09 2022
    On a sunny day (Sat, 25 Jun 2022 20:22:46 -0700 (PDT)) it happened whit3rd <whit3rd@gmail.com> wrote in <682a4161-f73e-4b7f-ad78-9237c4291e62n@googlegroups.com>:

    On Saturday, June 25, 2022 at 3:10:38 PM UTC-7, palli...@gmail.com wrote:
    bob prohaska wrote:

    AIUI, current into a capacitor is dv/dt x C, so the square wave should
    be much worse in terms of peak current than my sine-wave case.

    ** Nope - a rectified square wave is pure DC.
    SMPSs used in pro-audio power amps are nearly all square wave inverters.

    If the load on an AC source were a capacitor, you'd get
    current= dv/dt x C, and if the load were a rectifier into a (capacitor in parallel with a resistor)
    you'd get something more benign. In a power brick, the load is a rectifier and (resistor-loaded?)
    regulator, like a capacitor in parallel with a current sink.

    The ramp up when the rectifier diodes turn on will be abrupt, lots of peak current,
    which was what the inductor was intended to moderate.

    If the hypothetical inductor saturates, it'll make a buzzing sound; that's annoying.

    In the UPS case you do not charge into an _empty_ capacitor, if the UPS functions right
    then it is just the discharge difference from the last mains period (depends on wallwart load),
    the peak current will be limited also by the resistance of the series diodes, and by the Zi from the UPS etc..
    Square wave charges for a longer time, so next period less drop to correct than with a sine...

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Allison@21:1/5 to Jan Panteltje on Sun Jun 26 05:00:35 2022
    Jan Panteltje wrote:

    =====================

    In the UPS case you do not charge into an _empty_ capacitor, if the UPS functions right
    then it is just the discharge difference from the last mains period (depends on wallwart load),
    the peak current will be limited also by the resistance of the series diodes, and by the Zi from the UPS etc..

    **Yep.

    Square wave charges for a longer time,

    ** Nonsense.

    No charging pulses AT ALL.
    It's fucking DC you fool.



    ..... Phil

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From legg@21:1/5 to pallison49@gmail.com on Sun Jun 26 08:43:40 2022
    On Sun, 26 Jun 2022 05:00:35 -0700 (PDT), Phil Allison
    <pallison49@gmail.com> wrote:

    Jan Panteltje wrote:

    =====================

    In the UPS case you do not charge into an _empty_ capacitor, if the UPS functions right
    then it is just the discharge difference from the last mains period (depends on wallwart load),
    the peak current will be limited also by the resistance of the series diodes,
    and by the Zi from the UPS etc..

    **Yep.

    Square wave charges for a longer time,

    ** Nonsense.

    No charging pulses AT ALL.
    It's fucking DC you fool.



    ..... Phil

    They're talking about wallwarts loading the output of
    a UPS inverter that generates a 120VAC output with either
    a square or sine waveform.

    Capacitive rectified input filters of the wallwarts'
    primary(SMPS), or capacitive rectified output filters
    of the wallwart's (linear) secondaries will produce a
    different 120VAC current crest factor, depending on
    whether they are fed by a square or sine wave.

    If a square wave has it's simplest form (+-120V ~180degree,
    then crest factor is low, but the capacitive rectified
    output voltage will be only 70% of that produced by a 120V
    sine source.

    If the square vave is tailored to produce a more similar
    output (peak to RMS ratio), with higher voltage at a
    reduced duty cycle, then crest factor of rectified current
    will increase, and can easily exceed that of the sinusoidal
    standard input. Input current will look more like an RC
    charge/discharge, than a haversine charge/RC discharge.

    RL

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to legg@nospam.magma.ca on Sun Jun 26 13:29:08 2022
    On a sunny day (Sun, 26 Jun 2022 08:43:40 -0400) it happened legg <legg@nospam.magma.ca> wrote in <9jjgbhhjkqbqjr4krsm1g9dco3oc495k2d@4ax.com>:

    On Sun, 26 Jun 2022 05:00:35 -0700 (PDT), Phil Allison
    <pallison49@gmail.com> wrote:

    Jan Panteltje wrote:

    =====================

    In the UPS case you do not charge into an _empty_ capacitor, if the UPS functions right
    then it is just the discharge difference from the last mains period (depends on wallwart load),
    the peak current will be limited also by the resistance of the series diodes,
    and by the Zi from the UPS etc..

    **Yep.

    Square wave charges for a longer time,

    ** Nonsense.

    No charging pulses AT ALL.
    It's fucking DC you fool.



    ..... Phil

    They're talking about wallwarts loading the output of
    a UPS inverter that generates a 120VAC output with either
    a square or sine waveform.

    Capacitive rectified input filters of the wallwarts'
    primary(SMPS), or capacitive rectified output filters
    of the wallwart's (linear) secondaries will produce a
    different 120VAC current crest factor, depending on
    whether they are fed by a square or sine wave.

    If a square wave has it's simplest form (+-120V ~180degree,
    then crest factor is low, but the capacitive rectified
    output voltage will be only 70% of that produced by a 120V
    sine source.

    If the square vave is tailored to produce a more similar
    output (peak to RMS ratio), with higher voltage at a
    reduced duty cycle, then crest factor of rectified current
    will increase, and can easily exceed that of the sinusoidal
    standard input. Input current will look more like an RC
    charge/discharge, than a haversine charge/RC discharge.

    RL

    Here the waveform of my cheap UPS loaded with a normal 25 W lightbulb:
    http://www.panteltje.com/pub/APC_UPS_ES700_waveform_25W_edison_bulb_load_IMG_0270.JPG

    measured a while back when it was new,
    230V AC 50Hz Europe, cannot read the Vpp from the picture
    but 230 * sqrt(2) = 325, *2 = 650 Vpp
    this looks like 5 to 6 divisions maybe around 500 to 600 Vpp (not sure). Waveform is interesting :-)

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From legg@21:1/5 to pNaonStpealmtje@yahoo.com on Sun Jun 26 10:27:49 2022
    On Sun, 26 Jun 2022 13:29:08 GMT, Jan Panteltje
    <pNaonStpealmtje@yahoo.com> wrote:

    On a sunny day (Sun, 26 Jun 2022 08:43:40 -0400) it happened legg ><legg@nospam.magma.ca> wrote in <9jjgbhhjkqbqjr4krsm1g9dco3oc495k2d@4ax.com>:

    On Sun, 26 Jun 2022 05:00:35 -0700 (PDT), Phil Allison >><pallison49@gmail.com> wrote:

    Jan Panteltje wrote:

    =====================

    In the UPS case you do not charge into an _empty_ capacitor, if the UPS functions right
    then it is just the discharge difference from the last mains period (depends on wallwart load),
    the peak current will be limited also by the resistance of the series diodes,
    and by the Zi from the UPS etc..

    **Yep.

    Square wave charges for a longer time,

    ** Nonsense.

    No charging pulses AT ALL.
    It's fucking DC you fool.



    ..... Phil

    They're talking about wallwarts loading the output of
    a UPS inverter that generates a 120VAC output with either
    a square or sine waveform.

    Capacitive rectified input filters of the wallwarts'
    primary(SMPS), or capacitive rectified output filters
    of the wallwart's (linear) secondaries will produce a
    different 120VAC current crest factor, depending on
    whether they are fed by a square or sine wave.

    If a square wave has it's simplest form (+-120V ~180degree,
    then crest factor is low, but the capacitive rectified
    output voltage will be only 70% of that produced by a 120V
    sine source.

    If the square vave is tailored to produce a more similar
    output (peak to RMS ratio), with higher voltage at a
    reduced duty cycle, then crest factor of rectified current
    will increase, and can easily exceed that of the sinusoidal
    standard input. Input current will look more like an RC
    charge/discharge, than a haversine charge/RC discharge.

    RL

    Here the waveform of my cheap UPS loaded with a normal 25 W lightbulb:
    http://www.panteltje.com/pub/APC_UPS_ES700_waveform_25W_edison_bulb_load_IMG_0270.JPG

    measured a while back when it was new,
    230V AC 50Hz Europe, cannot read the Vpp from the picture
    but 230 * sqrt(2) = 325, *2 = 650 Vpp
    this looks like 5 to 6 divisions maybe around 500 to 600 Vpp (not sure). >Waveform is interesting :-)

    That's the modified square wave. It will produce quite peaky
    current waveforms in a capacitive rectified filter.

    But, as you've said, if it works, it works. The OP was trying to
    predict performance, based on insufficient information.

    RL

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to legg on Sun Jun 26 07:52:06 2022
    On Sun, 26 Jun 2022 10:27:49 -0400, legg <legg@nospam.magma.ca> wrote:

    On Sun, 26 Jun 2022 13:29:08 GMT, Jan Panteltje
    <pNaonStpealmtje@yahoo.com> wrote:

    On a sunny day (Sun, 26 Jun 2022 08:43:40 -0400) it happened legg >><legg@nospam.magma.ca> wrote in <9jjgbhhjkqbqjr4krsm1g9dco3oc495k2d@4ax.com>: >>
    On Sun, 26 Jun 2022 05:00:35 -0700 (PDT), Phil Allison >>><pallison49@gmail.com> wrote:

    Jan Panteltje wrote:

    =====================

    In the UPS case you do not charge into an _empty_ capacitor, if the UPS functions right
    then it is just the discharge difference from the last mains period (depends on wallwart load),
    the peak current will be limited also by the resistance of the series diodes,
    and by the Zi from the UPS etc..

    **Yep.

    Square wave charges for a longer time,

    ** Nonsense.

    No charging pulses AT ALL.
    It's fucking DC you fool.



    ..... Phil

    They're talking about wallwarts loading the output of
    a UPS inverter that generates a 120VAC output with either
    a square or sine waveform.

    Capacitive rectified input filters of the wallwarts'
    primary(SMPS), or capacitive rectified output filters
    of the wallwart's (linear) secondaries will produce a
    different 120VAC current crest factor, depending on
    whether they are fed by a square or sine wave.

    If a square wave has it's simplest form (+-120V ~180degree,
    then crest factor is low, but the capacitive rectified
    output voltage will be only 70% of that produced by a 120V
    sine source.

    If the square vave is tailored to produce a more similar
    output (peak to RMS ratio), with higher voltage at a
    reduced duty cycle, then crest factor of rectified current
    will increase, and can easily exceed that of the sinusoidal
    standard input. Input current will look more like an RC
    charge/discharge, than a haversine charge/RC discharge.

    RL

    Here the waveform of my cheap UPS loaded with a normal 25 W lightbulb:
    http://www.panteltje.com/pub/APC_UPS_ES700_waveform_25W_edison_bulb_load_IMG_0270.JPG

    measured a while back when it was new,
    230V AC 50Hz Europe, cannot read the Vpp from the picture
    but 230 * sqrt(2) = 325, *2 = 650 Vpp
    this looks like 5 to 6 divisions maybe around 500 to 600 Vpp (not sure). >>Waveform is interesting :-)

    That's the modified square wave. It will produce quite peaky
    current waveforms in a capacitive rectified filter.

    But, as you've said, if it works, it works. The OP was trying to
    predict performance, based on insufficient information.

    RL

    I can imagine a fast rise heating up the first cap in a non-PFC wart.
    Their usual failure mode is a bad cap. Might stress the usual series
    resistor too.

    A temperature comparison wouldn't be difficult.

    (I'm designing power supplies lately, and cap esr heating is part of
    the puzzle.)

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to legg@nospam.magma.ca on Sun Jun 26 15:28:24 2022
    On a sunny day (Sun, 26 Jun 2022 10:27:49 -0400) it happened legg <legg@nospam.magma.ca> wrote in <asqgbh545t97hl10p0mlm2j66li2pe42tq@4ax.com>:

    On Sun, 26 Jun 2022 13:29:08 GMT, Jan Panteltje
    <pNaonStpealmtje@yahoo.com> wrote:
    Here the waveform of my cheap UPS loaded with a normal 25 W lightbulb:
    http://www.panteltje.com/pub/APC_UPS_ES700_waveform_25W_edison_bulb_load_IMG_0270.JPG

    measured a while back when it was new,
    230V AC 50Hz Europe, cannot read the Vpp from the picture
    but 230 * sqrt(2) = 325, *2 = 650 Vpp
    this looks like 5 to 6 divisions maybe around 500 to 600 Vpp (not sure). >>Waveform is interesting :-)

    That's the modified square wave. It will produce quite peaky
    current waveforms in a capacitive rectified filter.

    But, as you've said, if it works, it works. The OP was trying to
    predict performance, based on insufficient information.

    Yes, and most of the wallwarts I have have a big input voltage range
    like 110 to 230 V AC.

    That gives the UPC some time to come in in case of 230V :-)

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Allison@21:1/5 to legg on Sun Jun 26 18:13:34 2022
    legg wrote:
    ===============
    Phil Allison


    Square wave charges for a longer time,

    ** Nonsense.

    No charging pulses AT ALL.
    It's fucking DC you fool.



    If a square wave has it's simplest form (+-120V ~180degree,
    then crest factor is low, but the capacitive rectified
    output voltage will be only 70% of that produced by a 120V
    sine source.


    ** The man said " square wave " - over and over.

    If the square vave is tailored to produce a more similar
    output (peak to RMS ratio), with higher voltage at a
    reduced duty cycle,


    ** Not a *square wave* any more.




    ..... Phil

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From legg@21:1/5 to legg on Mon Jun 27 09:42:08 2022
    On Sat, 25 Jun 2022 07:32:27 -0400, legg <legg@nospam.magma.ca> wrote:

    On Sat, 25 Jun 2022 02:10:59 -0000 (UTC), bob prohaska
    <bp@www.zefox.net> wrote:

    I'm setting up a UPS for my computer/comms equipment using an >>inverter/charger and battery from Amazon. The equipment draw
    is only about 40 watts measured with a Kill-A-Watt, but all
    the associated wallwarts use capacitive-input switching power
    supplies. That means they only draw current at line peaks.

    My seat-of-the-pants guess is that the duty cycle is around 10%,
    meaning that the average 40 watts is really 400 watts 10% of the time. >>That's well within the continuous power rating of the inverter, which
    is 800 watts, so it's likely the setup will work as it is.

    The question is: Can the peak load be made closer to the average
    load by putting an inductor in the AC line feeding the wallwarts?

    If anybody's been through this exercise I'd be grateful for guidance.

    Thanks for reading,

    bob prohaska



    I did some passive correction for off-the-shelf 60Hz linears in
    the 80s. Best effects achieved using a saturable choke and
    quasi-resonant capacitor, over a limited range of power levels
    for any specific installation.

    The parts are generally impractical for a hobbyist to get
    ahold of, though restacking laminations from unvarnished scrap
    is possible. Requires good VP Impregnation to silence the
    final iteration.

    The actual current phase angle shifted from leading to lagging
    over the useful range. Output voltage into the 60Hz capacitive
    load was flat-topped, affecting the low-line voltage performance.
    The choke/cap combination supported the output difference
    during line current reversal.

    It's no good guessing what the current waveshape is; you've
    got to measure it / scope it. Line current transformers are
    pretty cheap these days, often included in <$10 wattmeters
    from off-shore sources. A scope is useful, but more expensive.

    A lot of modern wall-warts are actually PFC compliant, through
    the use of dedicated low power integrated controllers. These
    employ valley-fill or critical-conduction (FM) off-line switchers >economically, at power levels as low as 5W.

    Don't guess. Measure. Read specs of devices involved.

    Don't go overboard. Your UPS output may be more tolerant of peak
    loads than you assume, and your loads may be less peaky, simply
    due to industry commodity trends and available parts.

    RL

    Some work on different rectifier and filter/pre-filter circuitry
    was published by Richard Redl and Laszlo Balogh ~1995.
    Some notes I made in the 80s, on the simplest LC configuration
    are also included in this zip file.

    In the latter, the effect of series choke saturation at above-
    nominal loads is illustrated.

    http://ve3ute.ca/query/passive_power_factor_diag.zip

    When standards docs start talking about total harmonic distortion
    and specs include power factors >95%, you can pretty much rule out
    passive approaches. They can be simple, reliable, quiet and
    effective in reducing generator and interconnection losses.
    . . . which is the OP's actual concern.

    RL

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Fred Bloggs@21:1/5 to bob prohaska on Mon Jun 27 14:54:53 2022
    On Friday, June 24, 2022 at 10:11:06 PM UTC-4, bob prohaska wrote:
    I'm setting up a UPS for my computer/comms equipment using an inverter/charger and battery from Amazon. The equipment draw
    is only about 40 watts measured with a Kill-A-Watt, but all
    the associated wallwarts use capacitive-input switching power
    supplies. That means they only draw current at line peaks.

    My seat-of-the-pants guess is that the duty cycle is around 10%,
    meaning that the average 40 watts is really 400 watts 10% of the time.
    That's well within the continuous power rating of the inverter, which
    is 800 watts, so it's likely the setup will work as it is.

    The question is: Can the peak load be made closer to the average
    load by putting an inductor in the AC line feeding the wallwarts?

    If anybody's been through this exercise I'd be grateful for guidance.

    Thanks for reading,

    Look at the plug-in output voltage inverter-fed versus line-fed. If no difference, then no issue. Look at the inverter RMS output with and without a bunch of plug-ins. If no difference then no issue.



    bob prohaska

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Fred Bloggs@21:1/5 to John Doe on Mon Jun 27 15:33:55 2022
    On Saturday, June 25, 2022 at 1:24:40 AM UTC-4, John Doe wrote:
    Jan Panteltje <pNaonSt...@yahoo.com> wrote:
    bob prohaska wrote:

    I'm setting up a UPS for my computer/comms equipment using an >>inverter/charger and battery from Amazon. The equipment draw is only >>about 40 watts measured with a Kill-A-Watt, but all the associated >>wallwarts use capacitive-input switching power supplies. That means
    they only draw current at line peaks.

    My seat-of-the-pants guess is that the duty cycle is around 10%, meaning >>that the average 40 watts is really 400 watts 10% of the time. That's >>well within the continuous power rating of the inverter, which is 800 >>watts, so it's likely the setup will work as it is.

    The question is: Can the peak load be made closer to the average load by >>putting an inductor in the AC line feeding the wallwarts?

    If anybody's been through this exercise I'd be grateful for guidance.
    Interesting question, my cheap UPS seems to put out a square wave I wondered if the flat tops are actually not better for the wall warts as the charging part is longer than with a sine wave top... Been working
    now fine for a year or so with this thing, comes in almost every day
    these days with mains company fiddling,.. flashing light bulbs sometimes here too. To backup for longer times I have a pure sine wave 2 kW converter and a 250 Ah lifepo4 battery.. So I can keep watching sat TV
    or even cook food. More than 10 wallwarts on that UPS now, some
    Raspberry Pi, some USB hubs, some cameras., also security recorder, monitors... .. audio amp... 4 TB harddisks... I would personally not bother with a a series inductor...
    For a personal computer only... I use a Tripp-Lite LC1200. No battery at all. I don't recall the last time we had a power failure that lasted more than an moment. But there has been flickering. The line conditioner works great for momentary outages, no messing with a battery.

    Of course that doesn't suit everybody.

    They just lifted the same technology used in inverter generators. If it coasts through what you call a momentary outage then it wasn't an outage. The price is pretty good but then again 1200 Watt is not really that much. Are you mining bitcoins or
    something? What in the world kind of computer setup requires 1200W these days...

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Doe@21:1/5 to Fred Bloggs on Tue Jun 28 02:10:27 2022
    By "momentary outage", I mean momentary loss of power. Like a dip, a drop,
    a sag, whatever you want to call it.

    I have a 1200 W line conditioner because for overkill. I guess it might
    help increase the momentary outage protection. Other stuff flickers, but
    not stuff connected to the line conditioner (like my PC or its monitor).
    Even if it doesn't help, it doesn't hurt.

    It's worked great without having to mess with a battery. When the power
    does go off for more than a second, the PC stays off instead of Windows rebooting. But that hasn't happened in years.

    That line conditioner with its clicking sound and LEDs also keeps one
    aware of room/house/neighborhood voltage. I like being aware of stuff.



    Fred Bloggs <bloggs.fredbloggs.fred@gmail.com> wrote:

    On Saturday, June 25, 2022 at 1:24:40 AM UTC-4, John Doe wrote:
    Jan Panteltje <pNaonSt...@yahoo.com> wrote:
    bob prohaska wrote:

    I'm setting up a UPS for my computer/comms equipment using an
    inverter/charger and battery from Amazon. The equipment draw is only
    about 40 watts measured with a Kill-A-Watt, but all the associated
    wallwarts use capacitive-input switching power supplies. That means
    they only draw current at line peaks.

    My seat-of-the-pants guess is that the duty cycle is around 10%, meanin
    g
    that the average 40 watts is really 400 watts 10% of the time. That's

    well within the continuous power rating of the inverter, which is 800

    watts, so it's likely the setup will work as it is.

    The question is: Can the peak load be made closer to the average load b
    y
    putting an inductor in the AC line feeding the wallwarts?

    If anybody's been through this exercise I'd be grateful for guidance.
    Interesting question, my cheap UPS seems to put out a square wave I
    wondered if the flat tops are actually not better for the wall warts as

    the charging part is longer than with a sine wave top... Been working

    now fine for a year or so with this thing, comes in almost every day
    these days with mains company fiddling,.. flashing light bulbs sometime
    s
    here too. To backup for longer times I have a pure sine wave 2 kW
    converter and a 250 Ah lifepo4 battery.. So I can keep watching sat TV

    or even cook food. More than 10 wallwarts on that UPS now, some
    Raspberry Pi, some USB hubs, some cameras., also security recorder,
    monitors... .. audio amp... 4 TB harddisks... I would personally not
    bother with a a series inductor...
    For a personal computer only... I use a Tripp-Lite LC1200. No battery at

    all. I don't recall the last time we had a power failure that lasted more

    than an moment. But there has been flickering. The line conditioner works

    great for momentary outages, no messing with a battery.

    Of course that doesn't suit everybody.

    They just lifted the same technology used in inverter generators. If it coasts through what you call a momentary outage then it wasn't an outage. The price is pretty good but then again 1200 Watt is not really that much. Are you mining bitcoins or
    something? What in the world kind of computer setup requires 1200W these days...


    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to legg@nospam.magma.ca on Tue Jun 28 08:10:11 2022
    On a sunny day (Mon, 27 Jun 2022 09:42:08 -0400) it happened legg <legg@nospam.magma.ca> wrote in <mlbjbhp55bpidiekuu6pjjsk607695aths@4ax.com>:

    On Sat, 25 Jun 2022 07:32:27 -0400, legg <legg@nospam.magma.ca> wrote:

    On Sat, 25 Jun 2022 02:10:59 -0000 (UTC), bob prohaska
    <bp@www.zefox.net> wrote:

    I'm setting up a UPS for my computer/comms equipment using an >>>inverter/charger and battery from Amazon. The equipment draw
    is only about 40 watts measured with a Kill-A-Watt, but all
    the associated wallwarts use capacitive-input switching power
    supplies. That means they only draw current at line peaks.

    My seat-of-the-pants guess is that the duty cycle is around 10%,
    meaning that the average 40 watts is really 400 watts 10% of the time. >>>That's well within the continuous power rating of the inverter, which
    is 800 watts, so it's likely the setup will work as it is.

    The question is: Can the peak load be made closer to the average
    load by putting an inductor in the AC line feeding the wallwarts?

    If anybody's been through this exercise I'd be grateful for guidance.

    Thanks for reading,

    bob prohaska



    I did some passive correction for off-the-shelf 60Hz linears in
    the 80s. Best effects achieved using a saturable choke and
    quasi-resonant capacitor, over a limited range of power levels
    for any specific installation.

    The parts are generally impractical for a hobbyist to get
    ahold of, though restacking laminations from unvarnished scrap
    is possible. Requires good VP Impregnation to silence the
    final iteration.

    The actual current phase angle shifted from leading to lagging
    over the useful range. Output voltage into the 60Hz capacitive
    load was flat-topped, affecting the low-line voltage performance.
    The choke/cap combination supported the output difference
    during line current reversal.

    It's no good guessing what the current waveshape is; you've
    got to measure it / scope it. Line current transformers are
    pretty cheap these days, often included in <$10 wattmeters
    from off-shore sources. A scope is useful, but more expensive.

    A lot of modern wall-warts are actually PFC compliant, through
    the use of dedicated low power integrated controllers. These
    employ valley-fill or critical-conduction (FM) off-line switchers >>economically, at power levels as low as 5W.

    Don't guess. Measure. Read specs of devices involved.

    Don't go overboard. Your UPS output may be more tolerant of peak
    loads than you assume, and your loads may be less peaky, simply
    due to industry commodity trends and available parts.

    RL

    Some work on different rectifier and filter/pre-filter circuitry
    was published by Richard Redl and Laszlo Balogh ~1995.
    Some notes I made in the 80s, on the simplest LC configuration
    are also included in this zip file.

    In the latter, the effect of series choke saturation at above-
    nominal loads is illustrated.

    http://ve3ute.ca/query/passive_power_factor_diag.zip

    When standards docs start talking about total harmonic distortion
    and specs include power factors >95%, you can pretty much rule out
    passive approaches. They can be simple, reliable, quiet and
    effective in reducing generator and interconnection losses.
    . . . which is the OP's actual concern.

    RL

    I did some back of the envelope calculation on (well actually I used wcalc)
    how much the input elctrolytic in a 12 W (12 V 1 A) wallwart discharges
    between mains periods with a bridge (so 10 mS here in 50 Hz land)
    IIRC that was about 57 volt ripple! on that tiny cap (usually 4.7 uF / 400 V type).
    No wonder all those electrolytics fail (have repaired many wallwarts here,
    BTW I also use floorwarts:
    http://panteltje.com/pub/floor_warts_IXIMG_0790.JPG
    all that on same UPS too.

    Primary cap discharge current between mains peaks:
    Given secundary 12 V 1 A and 350 V on primary cap 12 / 350 = 34 mA,
    but taking into account efficiency say 50 mA then if cap is 5 uF and t = 10 mS As Q = C.U = i.t -> U = i.t / C
    = (50E-3 * 10E-3) / 5E-6 = 100 V ripple!
    50 V ripple for a 10 uF...

    4.7 uF 400 V seems to be the normal in those small wallwarts (5 V 1 A), so I have a bunch of those,
    and also some big ones for the secondary caps, those often get puffed too.

    Maybe I goofed the math, but next time one goes I will scope that ripple Normally you can visually spot those bad caps because they will all be swollen.

    Anybody measured the ripple?

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Allison@21:1/5 to All on Tue Jun 28 03:42:04 2022
    Jan Panteltje wrote more rubbish: --------------------------------------------------------

    I did some back of the envelope calculation on (well actually I used wcalc) how much the input elctrolytic in a 12 W (12 V 1 A) wallwart discharges between mains periods with a bridge (so 10 mS here in 50 Hz land)
    IIRC that was about 57 volt ripple! on that tiny cap (usually 4.7 uF / 400 V type).


    ** So 15% p-p ripple. ( 57/340)
    Nothing odd about that.

    No wonder all those electrolytics fail .....

    ** Bullshit.

    Anybody measured the ripple?

    ** Why ?

    An any case, most plug-pak supplies operate well below their max current ratings.
    If electro caps fail early - it is due to internal temp rise only.

    Plus the use of cheap as possible parts.



    ..... Phil

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to Allison on Tue Jun 28 11:55:45 2022
    On a sunny day (Tue, 28 Jun 2022 03:42:04 -0700 (PDT)) it happened Phil
    Allison <pallison49@gmail.com> wrote in <38a7b4bd-81b5-42d3-a9a9-de151a557414n@googlegroups.com>:

    Jan Panteltje wrote more rubbish:
    --------------------------------------------------------

    I did some back of the envelope calculation on (well actually I used wcalc) >> how much the input elctrolytic in a 12 W (12 V 1 A) wallwart discharges
    between mains periods with a bridge (so 10 mS here in 50 Hz land)
    IIRC that was about 57 volt ripple! on that tiny cap (usually 4.7 uF / 400 V type).


    ** So 15% p-p ripple. ( 57/340)
    Nothing odd about that.

    Well the same thing is specified from 110 V to 230 V AC
    So double the current and the ripple AGAIN when used in a 110V world (ut 60 Hz is 5/6 * 10 mS so that helps.


    No wonder all those electrolytics fail .....

    ** Bullshit.

    Do not eat it! Live on a farm?

    Anybody measured the ripple?

    ** Why ?

    Why do humming beans exist? Why is water wet?


    An any case, most plug-pak supplies operate well below their max current ratings.

    For example the raspberry supplies, when more things are plugged into the USB are maxed out
    That is why I have now 2 USB hubs on the Pi4s each has its own supply.

    If electro caps fail early - it is due to internal temp rise only.

    The elcos get hot because of the high ripple current creating heat and detoriation of the cap,
    creating more heat ... a run-away process.



    Plus the use of cheap as possible parts.

    Sure good electrolytics are expensive.
    Bigger ones too -:)

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Allison@21:1/5 to Jan Panteltje is a fucking IDIOT on Tue Jun 28 05:24:15 2022
    Jan Panteltje is a fucking IDIOT wrote:
    =============================


    ** So 15% p-p ripple. ( 57/340)
    Nothing odd about that.
    Well the same thing is specified from 110 V to 230 V AC
    So double the current and the ripple AGAIN when used in a 110V world (ut 60 Hz is 5/6 * 10 mS so that helps.
    No wonder all those electrolytics fail .....

    ** Bullshit.

    Do not eat it! Live on a farm?

    ** Fuck you - imbecile.

    Anybody measured the ripple?

    ** Why ?

    Why do humming beans exist?

    ** So you have no reason at all ? zzzzzzzzz...

    An any case, most plug-pak supplies operate well below their max current ratings.

    For example ....

    ** Yawwnnn - more false logic idiocy.


    If electro caps fail early - it is due to internal temp rise only.


    The elcos get hot because of the high ripple current creating heat and detoriation of the cap,

    ** Not at 15% they fucking don't - you liar.

    Plus the use of cheap as possible parts.

    Sure good electrolytics are expensive.

    ** Yawwnnn - more false logic idiocy.

    Scuse me while I vomit.


    ..... Phil

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From legg@21:1/5 to pNaonStpealmtje@yahoo.com on Tue Jun 28 09:26:45 2022
    On Tue, 28 Jun 2022 08:10:11 GMT, Jan Panteltje
    <pNaonStpealmtje@yahoo.com> wrote:

    On a sunny day (Mon, 27 Jun 2022 09:42:08 -0400) it happened legg ><legg@nospam.magma.ca> wrote in <mlbjbhp55bpidiekuu6pjjsk607695aths@4ax.com>:

    On Sat, 25 Jun 2022 07:32:27 -0400, legg <legg@nospam.magma.ca> wrote:

    On Sat, 25 Jun 2022 02:10:59 -0000 (UTC), bob prohaska
    <bp@www.zefox.net> wrote:

    I'm setting up a UPS for my computer/comms equipment using an >>>>inverter/charger and battery from Amazon. The equipment draw
    is only about 40 watts measured with a Kill-A-Watt, but all
    the associated wallwarts use capacitive-input switching power >>>>supplies. That means they only draw current at line peaks.

    My seat-of-the-pants guess is that the duty cycle is around 10%, >>>>meaning that the average 40 watts is really 400 watts 10% of the time. >>>>That's well within the continuous power rating of the inverter, which >>>>is 800 watts, so it's likely the setup will work as it is.

    The question is: Can the peak load be made closer to the average
    load by putting an inductor in the AC line feeding the wallwarts?

    If anybody's been through this exercise I'd be grateful for guidance.

    Thanks for reading,

    bob prohaska



    I did some passive correction for off-the-shelf 60Hz linears in
    the 80s. Best effects achieved using a saturable choke and
    quasi-resonant capacitor, over a limited range of power levels
    for any specific installation.

    The parts are generally impractical for a hobbyist to get
    ahold of, though restacking laminations from unvarnished scrap
    is possible. Requires good VP Impregnation to silence the
    final iteration.

    The actual current phase angle shifted from leading to lagging
    over the useful range. Output voltage into the 60Hz capacitive
    load was flat-topped, affecting the low-line voltage performance.
    The choke/cap combination supported the output difference
    during line current reversal.

    It's no good guessing what the current waveshape is; you've
    got to measure it / scope it. Line current transformers are
    pretty cheap these days, often included in <$10 wattmeters
    from off-shore sources. A scope is useful, but more expensive.

    A lot of modern wall-warts are actually PFC compliant, through
    the use of dedicated low power integrated controllers. These
    employ valley-fill or critical-conduction (FM) off-line switchers >>>economically, at power levels as low as 5W.

    Don't guess. Measure. Read specs of devices involved.

    Don't go overboard. Your UPS output may be more tolerant of peak
    loads than you assume, and your loads may be less peaky, simply
    due to industry commodity trends and available parts.

    RL

    Some work on different rectifier and filter/pre-filter circuitry
    was published by Richard Redl and Laszlo Balogh ~1995.
    Some notes I made in the 80s, on the simplest LC configuration
    are also included in this zip file.

    In the latter, the effect of series choke saturation at above-
    nominal loads is illustrated.

    http://ve3ute.ca/query/passive_power_factor_diag.zip

    When standards docs start talking about total harmonic distortion
    and specs include power factors >95%, you can pretty much rule out
    passive approaches. They can be simple, reliable, quiet and
    effective in reducing generator and interconnection losses.
    . . . which is the OP's actual concern.

    RL

    I did some back of the envelope calculation on (well actually I used wcalc) >how much the input elctrolytic in a 12 W (12 V 1 A) wallwart discharges >between mains periods with a bridge (so 10 mS here in 50 Hz land)
    IIRC that was about 57 volt ripple! on that tiny cap (usually 4.7 uF / 400 V type).
    No wonder all those electrolytics fail (have repaired many wallwarts here, >BTW I also use floorwarts:
    http://panteltje.com/pub/floor_warts_IXIMG_0790.JPG
    all that on same UPS too.

    Primary cap discharge current between mains peaks:
    Given secundary 12 V 1 A and 350 V on primary cap 12 / 350 = 34 mA,
    but taking into account efficiency say 50 mA then if cap is 5 uF and t = 10 mS
    As Q = C.U = i.t -> U = i.t / C
    = (50E-3 * 10E-3) / 5E-6 = 100 V ripple!
    50 V ripple for a 10 uF...

    4.7 uF 400 V seems to be the normal in those small wallwarts (5 V 1 A), so I have a bunch of those,
    and also some big ones for the secondary caps, those often get puffed too.

    Maybe I goofed the math, but next time one goes I will scope that ripple >Normally you can visually spot those bad caps because they will all be swollen.

    Anybody measured the ripple?

    Electrolytic life is rms current dependent, among other things (like temperature).

    If you convert your delta-voltage into current, you'll get a more
    meaningful value that can be compared to published ratings.
    Higher currents actually occur during the cap charging period and
    high peak-to-average current ratios can give punishing rms values
    for the same average filter output current.

    Electrolytics normally have a predicted life some orders of
    magnitude shorter than most other components - and they are the
    main non-moving parts that determine of predicted MTBF in
    commercial products running off the AC line, through a rectified
    filter.

    There have been eras where bad mfr formulations, misapplication
    of product and simple bad design made early mortality abnormally
    evident.

    RL

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Allison@21:1/5 to legg on Tue Jun 28 13:37:59 2022
    legg wrote:
    ================

    ** Learn to trim - asshole.


    Anybody measured the ripple?

    Electrolytic life is rms current dependent, among other things (like temperature).

    ** You just made that mad crap up.

    Temp is the single determining factor on expected life.
    Almost always the local ambient completely dominates.

    Electrolytics normally have a predicted life some orders of
    magnitude shorter than most other components

    ** Then in practice often outlast the lot.
    The one exception being vacuum tubes.



    ..... Phil

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From bob prohaska@21:1/5 to Phil Allison on Wed Jun 29 02:45:54 2022
    Phil Allison <pallison49@gmail.com> wrote:
    bob prohaska wrote:
    ======================

    AIUI, current into a capacitor is dv/dt x C, so the square wave should
    be much worse in terms of peak current than my sine-wave case.

    ** Nope - a rectified square wave is pure DC.
    SMPSs used in pro-audio power amps are nearly all square wave inverters.

    Hmmm, _maybe_ I get your point. The input capacitors never discharge,
    so dv/dt is zero. Thus, no inrush peak after startup.

    Dammit. Didn't need a sine inverter at all..... It's on the bench
    now, waiting for the battery to arrive.

    Thanks for posting!

    bob prohaska



    Battery to AC inverters are different.


    ..... Phil



    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Allison@21:1/5 to All on Wed Jun 29 05:32:38 2022
    legg wrote:
    ----------------------

    ** Dear Mr legg.

    Kindly go stick your fat stupid head up a dead bear's arse .
    YOU are so dumb, make pig ignorance look like genius.

    Fuck you and fuck off.
    You ASD fucked cunt.



    ..... Phil

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From legg@21:1/5 to pallison49@gmail.com on Wed Jun 29 08:23:22 2022
    On Tue, 28 Jun 2022 13:37:59 -0700 (PDT), Phil Allison
    <pallison49@gmail.com> wrote:

    legg wrote:
    ================

    ** Learn to trim - asshole.


    Anybody measured the ripple?

    Electrolytic life is rms current dependent, among other things (like
    temperature).

    If you stick one next to a vacuum tube, it's received radiated that
    dominates part temperature, and voltage stress of the app that
    dominates.

    ** You just made that mad crap up.

    If you've ever calculated mtbf under Mil Hdbk 217, or Belcore,
    you'd be aware of dominating life factors.

    Temp is the single determining factor on expected life.
    Almost always the local ambient completely dominates.

    Current forces self-rise due the part's ESR and limited
    body surface area, (unless you stick it next to a hot radiator).
    The actual relevant temperature is measured on the component's
    body.

    Electrolytics normally have a predicted life some orders of
    magnitude shorter than most other components

    ** Then in practice often outlast the lot.
    The one exception being vacuum tubes.

    Given a reliable heater and low vibration, tube life is
    roughly related to the temperature of the glass envelope.

    http://ve3ute.ca/2000a.html




    ..... Phil

    RL

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to legg on Wed Jun 29 07:19:46 2022
    On Wed, 29 Jun 2022 08:23:22 -0400, legg <legg@nospam.magma.ca> wrote:

    On Tue, 28 Jun 2022 13:37:59 -0700 (PDT), Phil Allison
    <pallison49@gmail.com> wrote:

    legg wrote:
    ================

    ** Learn to trim - asshole.


    Anybody measured the ripple?

    Electrolytic life is rms current dependent, among other things (like
    temperature).

    If you stick one next to a vacuum tube, it's received radiated that
    dominates part temperature, and voltage stress of the app that
    dominates.

    ** You just made that mad crap up.

    If you've ever calculated mtbf under Mil Hdbk 217, or Belcore,
    you'd be aware of dominating life factors.

    Belcore has no derating factor for bad design. That often dominates
    MTBF.



    Temp is the single determining factor on expected life.
    Almost always the local ambient completely dominates.

    Current forces self-rise due the part's ESR and limited
    body surface area, (unless you stick it next to a hot radiator).
    The actual relevant temperature is measured on the component's
    body.

    We are designing a fancy switching power supply and need a 20 uF cap
    that can handle several amps RMS, a 250 KHz triangle from a
    half-bridge and an inductor. We are thinking about using four 4.7 uF radial-leaded film caps in parallel.

    We have samples of several types on order. I plan to set up a test rig
    and push amps of triangle into them and see how hot they get. May as
    well snoop the waveform across each cap while I do that.

    Film cap data sheets are typically not much help. They might spec a
    few sinewave loss tangents and maybe allowable voltage vs frequency,
    but rarely spec ESR or ESL or any thermals. We have to measure all
    that.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Fred Bloggs@21:1/5 to jla...@highlandsniptechnology.com on Wed Jun 29 08:18:39 2022
    On Wednesday, June 29, 2022 at 10:20:07 AM UTC-4, jla...@highlandsniptechnology.com wrote:
    On Wed, 29 Jun 2022 08:23:22 -0400, legg <le...@nospam.magma.ca> wrote:

    On Tue, 28 Jun 2022 13:37:59 -0700 (PDT), Phil Allison
    <palli...@gmail.com> wrote:

    legg wrote:
    ================

    ** Learn to trim - asshole.


    Anybody measured the ripple?

    Electrolytic life is rms current dependent, among other things (like
    temperature).

    If you stick one next to a vacuum tube, it's received radiated that >dominates part temperature, and voltage stress of the app that
    dominates.

    ** You just made that mad crap up.

    If you've ever calculated mtbf under Mil Hdbk 217, or Belcore,
    you'd be aware of dominating life factors.
    Belcore has no derating factor for bad design. That often dominates
    MTBF.

    Temp is the single determining factor on expected life.
    Almost always the local ambient completely dominates.

    Current forces self-rise due the part's ESR and limited
    body surface area, (unless you stick it next to a hot radiator).
    The actual relevant temperature is measured on the component's
    body.
    We are designing a fancy switching power supply and need a 20 uF cap
    that can handle several amps RMS, a 250 KHz triangle from a
    half-bridge and an inductor. We are thinking about using four 4.7 uF radial-leaded film caps in parallel.

    We have samples of several types on order. I plan to set up a test rig
    and push amps of triangle into them and see how hot they get. May as
    well snoop the waveform across each cap while I do that.

    Film cap data sheets are typically not much help. They might spec a
    few sinewave loss tangents and maybe allowable voltage vs frequency,
    but rarely spec ESR or ESL or any thermals. We have to measure all
    that.

    These people don't figure current into life expectancy, only voltage and temperature.
    https://www.cde.com/resources/technical-papers/filmAPPguide.pdf

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to bloggs.fredbloggs.fred@gmail.com on Wed Jun 29 08:37:08 2022
    On Wed, 29 Jun 2022 08:18:39 -0700 (PDT), Fred Bloggs <bloggs.fredbloggs.fred@gmail.com> wrote:

    On Wednesday, June 29, 2022 at 10:20:07 AM UTC-4, jla...@highlandsniptechnology.com wrote:
    On Wed, 29 Jun 2022 08:23:22 -0400, legg <le...@nospam.magma.ca> wrote:

    On Tue, 28 Jun 2022 13:37:59 -0700 (PDT), Phil Allison
    <palli...@gmail.com> wrote:

    legg wrote:
    ================

    ** Learn to trim - asshole.


    Anybody measured the ripple?

    Electrolytic life is rms current dependent, among other things (like
    temperature).

    If you stick one next to a vacuum tube, it's received radiated that
    dominates part temperature, and voltage stress of the app that
    dominates.

    ** You just made that mad crap up.

    If you've ever calculated mtbf under Mil Hdbk 217, or Belcore,
    you'd be aware of dominating life factors.
    Belcore has no derating factor for bad design. That often dominates
    MTBF.

    Temp is the single determining factor on expected life.
    Almost always the local ambient completely dominates.

    Current forces self-rise due the part's ESR and limited
    body surface area, (unless you stick it next to a hot radiator).
    The actual relevant temperature is measured on the component's
    body.
    We are designing a fancy switching power supply and need a 20 uF cap
    that can handle several amps RMS, a 250 KHz triangle from a
    half-bridge and an inductor. We are thinking about using four 4.7 uF
    radial-leaded film caps in parallel.

    We have samples of several types on order. I plan to set up a test rig
    and push amps of triangle into them and see how hot they get. May as
    well snoop the waveform across each cap while I do that.

    Film cap data sheets are typically not much help. They might spec a
    few sinewave loss tangents and maybe allowable voltage vs frequency,
    but rarely spec ESR or ESL or any thermals. We have to measure all
    that.

    These people don't figure current into life expectancy, only voltage and temperature.
    https://www.cde.com/resources/technical-papers/filmAPPguide.pdf

    That's interesting but, typically, qualitative and theoretical. I'll
    have to test actual caps.

    We will have a lot of air flow too, which will increase allowable RMS
    current and needs to be quantified too. We should orient and space the
    caps to take advantage of the air cooling. This ain't simple.

    It's distressing, in electronics data sheets and literature, how
    seldom you find actual numbers. I recently bought a book about
    electronic cooling, but it's packed with equations and theory, with
    not a single worked-out case of blowing air over a flat plate. There
    is an equation, but it's a nightmare.

    If I had a 6" square of 0.062 thick aluminum, and blasted 200 f/m of
    air along both sides, what would theta be? I'll have to measure that.

    And what would the temp rise be of my 4.7u film caps, in degc/watt, in
    still air and with air flow? Gotta measure that too.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From whit3rd@21:1/5 to palli...@gmail.com on Wed Jun 29 12:07:14 2022
    On Tuesday, June 28, 2022 at 1:38:06 PM UTC-7, palli...@gmail.com wrote:
    legg wrote:
    ================

    ** Learn to trim - asshole.

    Anybody measured the ripple?

    Electrolytic life is rms current dependent, among other things (like temperature).
    ** You just made that mad crap up.

    Temp is the single determining factor on expected life.
    Almost always the local ambient completely dominates.

    Electrolytics normally have a predicted life some orders of
    magnitude shorter than most other components

    ** Then in practice often outlast the lot.
    The one exception being vacuum tubes.

    Electrolytic capacitors are active-chemistry devices; temperature affects the seals that hold the reagents in place, and either internal heat or ambient temperature
    will cause aging, irrespective of electrical stress. High ripple voltage is associated
    with processes that cause i nternal foils to become fractured.

    Vacuum tubes are also active-chemistry devices; usually become gassy due to slow
    diffusion of contaminants. There's better chemcal integrity available in solid state devices
    as far as aging is concerned. Batteries exemplify the worst chemical integrity in the business...
    you always want to check the dates on those!

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to jlarkin@highlandsniptechnology.com on Wed Jun 29 15:38:02 2022
    jlarkin@highlandsniptechnology.com wrote:
    On Wed, 29 Jun 2022 08:18:39 -0700 (PDT), Fred Bloggs <bloggs.fredbloggs.fred@gmail.com> wrote:

    On Wednesday, June 29, 2022 at 10:20:07 AM UTC-4, jla...@highlandsniptechnology.com wrote:
    On Wed, 29 Jun 2022 08:23:22 -0400, legg <le...@nospam.magma.ca> wrote:

    On Tue, 28 Jun 2022 13:37:59 -0700 (PDT), Phil Allison
    <palli...@gmail.com> wrote:

    legg wrote:
    ================

    ** Learn to trim - asshole.


    Anybody measured the ripple?

    Electrolytic life is rms current dependent, among other things (like >>>>>> temperature).

    If you stick one next to a vacuum tube, it's received radiated that
    dominates part temperature, and voltage stress of the app that
    dominates.

    ** You just made that mad crap up.

    If you've ever calculated mtbf under Mil Hdbk 217, or Belcore,
    you'd be aware of dominating life factors.
    Belcore has no derating factor for bad design. That often dominates
    MTBF.

    Temp is the single determining factor on expected life.
    Almost always the local ambient completely dominates.

    Current forces self-rise due the part's ESR and limited
    body surface area, (unless you stick it next to a hot radiator).
    The actual relevant temperature is measured on the component's
    body.
    We are designing a fancy switching power supply and need a 20 uF cap
    that can handle several amps RMS, a 250 KHz triangle from a
    half-bridge and an inductor. We are thinking about using four 4.7 uF
    radial-leaded film caps in parallel.

    We have samples of several types on order. I plan to set up a test rig
    and push amps of triangle into them and see how hot they get. May as
    well snoop the waveform across each cap while I do that.

    Film cap data sheets are typically not much help. They might spec a
    few sinewave loss tangents and maybe allowable voltage vs frequency,
    but rarely spec ESR or ESL or any thermals. We have to measure all
    that.

    These people don't figure current into life expectancy, only voltage and temperature.
    https://www.cde.com/resources/technical-papers/filmAPPguide.pdf

    That's interesting but, typically, qualitative and theoretical. I'll
    have to test actual caps.

    We will have a lot of air flow too, which will increase allowable RMS
    current and needs to be quantified too. We should orient and space the
    caps to take advantage of the air cooling. This ain't simple.

    It's distressing, in electronics data sheets and literature, how
    seldom you find actual numbers. I recently bought a book about
    electronic cooling, but it's packed with equations and theory, with
    not a single worked-out case of blowing air over a flat plate. There
    is an equation, but it's a nightmare.

    If I had a 6" square of 0.062 thick aluminum, and blasted 200 f/m of
    air along both sides, what would theta be? I'll have to measure that.

    And what would the temp rise be of my 4.7u film caps, in degc/watt, in
    still air and with air flow? Gotta measure that too.


    Even in an inviscid, incompressible fluid, the equations aren't all that simple. Forced-air cooling of macroscopic systems runs at some huge and
    highly variable Reynolds number, depending on where you are.

    There was a bit of a fad in the '90s for people to publish various semi-empirical papers on fan cooling, but that sort of died out.

    You can compute the thermodynamic limit, obviously, because you know the
    inlet temperature, the air mass, the maximum component temperature, and
    the heat dissipated, but most heat sink systems don't get anywhere near it.

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From legg@21:1/5 to All on Wed Jun 29 17:50:09 2022
    On Wed, 29 Jun 2022 07:19:46 -0700, jlarkin@highlandsniptechnology.com
    wrote:

    On Wed, 29 Jun 2022 08:23:22 -0400, legg <legg@nospam.magma.ca> wrote:

    On Tue, 28 Jun 2022 13:37:59 -0700 (PDT), Phil Allison >><pallison49@gmail.com> wrote:

    legg wrote:
    ================

    ** Learn to trim - asshole.


    Anybody measured the ripple?

    Electrolytic life is rms current dependent, among other things (like
    temperature).

    If you stick one next to a vacuum tube, it's received radiated that >>dominates part temperature, and voltage stress of the app that
    dominates.

    ** You just made that mad crap up.

    If you've ever calculated mtbf under Mil Hdbk 217, or Belcore,
    you'd be aware of dominating life factors.

    Belcore has no derating factor for bad design. That often dominates
    MTBF.

    The stress factors for measured voltage current and temperature are
    a fair indication of design integrity. Designs can be 'bad' for
    other reasons entirely.



    Temp is the single determining factor on expected life.
    Almost always the local ambient completely dominates.

    Current forces self-rise due the part's ESR and limited
    body surface area, (unless you stick it next to a hot radiator).
    The actual relevant temperature is measured on the component's
    body.

    We are designing a fancy switching power supply and need a 20 uF cap
    that can handle several amps RMS, a 250 KHz triangle from a
    half-bridge and an inductor. We are thinking about using four 4.7 uF >radial-leaded film caps in parallel.

    We have samples of several types on order. I plan to set up a test rig
    and push amps of triangle into them and see how hot they get. May as
    well snoop the waveform across each cap while I do that.

    Film cap data sheets are typically not much help. They might spec a
    few sinewave loss tangents and maybe allowable voltage vs frequency,
    but rarely spec ESR or ESL or any thermals. We have to measure all
    that.

    It's always been difficult determining film cap ratings.
    The dielectric losses usually have a positive temp co
    above 50C and the parts themselves can have some of the
    lowest part body temperature limits in the deck.

    Part construction and materials quality, though largely the
    product of automation, can vary. Not many other parts are
    dependent on a coat of paint for env integrity.

    Keep in mind that self-healing construction can mask
    a considerable defect level. You've probably pulled simple
    film decoupling caps out who's capacitance measured almost
    nothing compared to their original mfred values, due to
    repeated intervening self-healing processes.

    Philips published good information on polycarbonate, polyester
    and polypropylene parts, when they were still in the business
    of using them. Check their 'Components and Materials Part 15'
    prior to 1990. I don't think there's been much improvement on
    that. Siemens tended to be more spotty. CDE did some mil stuff
    that must have been backed up by something more than body
    temperature rise. Polycarbonate development has lost some steam
    due to issues with flammability.

    There were film caps in most early fluorescent bulb replacements,
    besides the usual HV electrolytic. At that temperature, it was a
    toss-up which failed first.

    Pulse-rated products get more attention to their reliability
    and ratings. If your part doesn't provide sufficient data,
    chances are it's a misapplication waiting to happen. Pulse
    steepness dV/dT (~peak current) is dependent on both the
    process characteristic voltage AND the part body size, so that
    the amps/uF can actually reduce with an increase in leadspacing.

    PPK and polyphenylene sulphide are potential rivals in some
    applications, with slightly higher temperature limits, but I
    don't recall anyone providing tabular or graphical data.

    Can't imagine where my notes could be on that stuff. Today, even
    the binder labels are illegible. Probably need a different kind
    of 'specs'.

    RL

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From legg@21:1/5 to All on Wed Jun 29 18:14:22 2022
    Anyways, wade through it and you may come up with
    something like this:

    http://ve3ute.ca/query/Polycarbonate_Current_100KHz_Philips.pdf

    It will be different for each dielectric, frequency of operation,
    temperature etc.

    RL

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Clifford Heath@21:1/5 to Phil Hobbs on Thu Jun 30 12:13:32 2022
    On 30/6/22 05:38, Phil Hobbs wrote:
    Even in an inviscid, incompressible fluid, the equations aren't all that simple.  Forced-air cooling of macroscopic systems runs at some huge and highly variable Reynolds number, depending on where you are.

    Pretty sure that Reynolds number cannot be defined for an inviscid
    liquid. But yeah, turbulent flows are difficult however you look at them.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to legg on Wed Jun 29 19:36:21 2022
    On Wed, 29 Jun 2022 18:14:22 -0400, legg <legg@nospam.magma.ca> wrote:

    Anyways, wade through it and you may come up with
    something like this:

    http://ve3ute.ca/query/Polycarbonate_Current_100KHz_Philips.pdf

    It will be different for each dielectric, frequency of operation,
    temperature etc.

    RL

    Gosh, real numbers. Thanks.

    I just got this. It's a high voltage half-bridge test board for frying inductors and film caps. People were doing another proto board so I
    hung this on the end as a v-score breakaway.

    https://www.dropbox.com/s/2x8z6yn29ab57xf/Z524_Wing_1.jpg?raw=1

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From legg@21:1/5 to All on Thu Jun 30 09:51:22 2022
    On Wed, 29 Jun 2022 19:36:21 -0700, jlarkin@highlandsniptechnology.com
    wrote:

    On Wed, 29 Jun 2022 18:14:22 -0400, legg <legg@nospam.magma.ca> wrote:

    Anyways, wade through it and you may come up with
    something like this:

    http://ve3ute.ca/query/Polycarbonate_Current_100KHz_Philips.pdf

    It will be different for each dielectric, frequency of operation, >>temperature etc.

    RL

    Gosh, real numbers. Thanks.

    I just got this. It's a high voltage half-bridge test board for frying >inductors and film caps. People were doing another proto board so I
    hung this on the end as a v-score breakaway.

    https://www.dropbox.com/s/2x8z6yn29ab57xf/Z524_Wing_1.jpg?raw=1

    One good way of frying film caps is to thermally couple them
    to hot chokes or power resistors.

    Like a lot of other parts, they depend on thermal conduction
    to the PCB.

    RL

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to Clifford Heath on Thu Jun 30 09:25:24 2022
    Clifford Heath wrote:
    On 30/6/22 05:38, Phil Hobbs wrote:
    Even in an inviscid, incompressible fluid, the equations aren't all
    that simple.  Forced-air cooling of macroscopic systems runs at some
    huge and highly variable Reynolds number, depending on where you are.

    Pretty sure that Reynolds number cannot be defined for an inviscid
    liquid. But yeah, turbulent flows are difficult however you look at them.

    My point exactly.

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Thu Jun 30 06:53:33 2022
    On Thu, 30 Jun 2022 09:25:24 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Clifford Heath wrote:
    On 30/6/22 05:38, Phil Hobbs wrote:
    Even in an inviscid, incompressible fluid, the equations aren't all
    that simple. Forced-air cooling of macroscopic systems runs at some
    huge and highly variable Reynolds number, depending on where you are.

    Pretty sure that Reynolds number cannot be defined for an inviscid
    liquid. But yeah, turbulent flows are difficult however you look at them.

    My point exactly.

    Cheers

    Phil Hobbs

    Sure. But is my plate 0.2 k/w, or is it 20 k/w?

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to legg on Thu Jun 30 07:13:07 2022
    On Thu, 30 Jun 2022 09:51:22 -0400, legg <legg@nospam.magma.ca> wrote:

    On Wed, 29 Jun 2022 19:36:21 -0700, jlarkin@highlandsniptechnology.com
    wrote:

    On Wed, 29 Jun 2022 18:14:22 -0400, legg <legg@nospam.magma.ca> wrote:

    Anyways, wade through it and you may come up with
    something like this:

    http://ve3ute.ca/query/Polycarbonate_Current_100KHz_Philips.pdf

    It will be different for each dielectric, frequency of operation, >>>temperature etc.

    RL

    Gosh, real numbers. Thanks.

    I just got this. It's a high voltage half-bridge test board for frying >>inductors and film caps. People were doing another proto board so I
    hung this on the end as a v-score breakaway.

    https://www.dropbox.com/s/2x8z6yn29ab57xf/Z524_Wing_1.jpg?raw=1

    One good way of frying film caps is to thermally couple them
    to hot chokes or power resistors.

    That's inelegant. I plan to pump in amps of 250 KHz triangle wave.


    Like a lot of other parts, they depend on thermal conduction
    to the PCB.

    We will have a lot of forced air flow, at least 200 f/m acoss both
    sides of our plugin boards. That will reduce cap temp rise by at least
    a factor of 2.

    Power resistor data sheets sometimes mention power vs air flow. I have
    seen suggestions of between 2:1 and 10:1 more power with air flow.

    I'll fire up the board and pump amps into various 4.7u radial film
    caps, blow some air on them, and measure temps. What else is a boy to
    do?

    I should try to evaluate how much cooling we might get through the
    leads. We could use big power pours on the pins to slurp out some
    heat. My first guess is that lead cooling will be minor.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to jlarkin@highlandsniptechnology.com on Thu Jun 30 14:52:03 2022
    jlarkin@highlandsniptechnology.com wrote:
    On Thu, 30 Jun 2022 09:25:24 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Clifford Heath wrote:
    On 30/6/22 05:38, Phil Hobbs wrote:
    Even in an inviscid, incompressible fluid, the equations aren't all
    that simple.  Forced-air cooling of macroscopic systems runs at some
    huge and highly variable Reynolds number, depending on where you are.

    Pretty sure that Reynolds number cannot be defined for an inviscid
    liquid. But yeah, turbulent flows are difficult however you look at them. >>
    My point exactly.


    Sure. But is my plate 0.2 k/w, or is it 20 k/w?


    A zero-order approximation would be to assume that the boundary layer is
    ~5 mm thick, and the plate behaves like still air of that thickness
    connected to an infinite heat sink at the outlet temperature.

    You can compute the outlet temperature using the mass flow rate, heat
    capacity of air, inlet temperature, and power dissipation.

    I'd expect things to improve faster than linearly with flow rate,
    because the boundary layer should thin down as well as the outlet
    temperature falling.

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to jlarkin@highlandsniptechnology.com on Thu Jun 30 14:53:46 2022
    jlarkin@highlandsniptechnology.com wrote:
    On Thu, 30 Jun 2022 09:51:22 -0400, legg <legg@nospam.magma.ca> wrote:

    On Wed, 29 Jun 2022 19:36:21 -0700, jlarkin@highlandsniptechnology.com
    wrote:

    On Wed, 29 Jun 2022 18:14:22 -0400, legg <legg@nospam.magma.ca> wrote:

    Anyways, wade through it and you may come up with
    something like this:

    http://ve3ute.ca/query/Polycarbonate_Current_100KHz_Philips.pdf

    It will be different for each dielectric, frequency of operation,
    temperature etc.

    RL

    Gosh, real numbers. Thanks.

    I just got this. It's a high voltage half-bridge test board for frying
    inductors and film caps. People were doing another proto board so I
    hung this on the end as a v-score breakaway.

    https://www.dropbox.com/s/2x8z6yn29ab57xf/Z524_Wing_1.jpg?raw=1

    One good way of frying film caps is to thermally couple them
    to hot chokes or power resistors.

    That's inelegant. I plan to pump in amps of 250 KHz triangle wave.


    Like a lot of other parts, they depend on thermal conduction
    to the PCB.

    We will have a lot of forced air flow, at least 200 f/m acoss both
    sides of our plugin boards. That will reduce cap temp rise by at least
    a factor of 2.

    Power resistor data sheets sometimes mention power vs air flow. I have
    seen suggestions of between 2:1 and 10:1 more power with air flow.

    I'll fire up the board and pump amps into various 4.7u radial film
    caps, blow some air on them, and measure temps. What else is a boy to
    do?

    I should try to evaluate how much cooling we might get through the
    leads. We could use big power pours on the pins to slurp out some
    heat. My first guess is that lead cooling will be minor.




    Film and foil caps work a lot better for that sort of use than
    metallized-film ones.

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Thu Jun 30 18:22:54 2022
    On Thu, 30 Jun 2022 14:52:03 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    jlarkin@highlandsniptechnology.com wrote:
    On Thu, 30 Jun 2022 09:25:24 -0400, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Clifford Heath wrote:
    On 30/6/22 05:38, Phil Hobbs wrote:
    Even in an inviscid, incompressible fluid, the equations aren't all
    that simple. Forced-air cooling of macroscopic systems runs at some >>>>> huge and highly variable Reynolds number, depending on where you are. >>>>
    Pretty sure that Reynolds number cannot be defined for an inviscid
    liquid. But yeah, turbulent flows are difficult however you look at them. >>>
    My point exactly.


    Sure. But is my plate 0.2 k/w, or is it 20 k/w?


    A zero-order approximation would be to assume that the boundary layer is
    ~5 mm thick, and the plate behaves like still air of that thickness
    connected to an infinite heat sink at the outlet temperature.

    You can compute the outlet temperature using the mass flow rate, heat >capacity of air, inlet temperature, and power dissipation.

    I'd expect things to improve faster than linearly with flow rate,
    because the boundary layer should thin down as well as the outlet
    temperature falling.

    Cheers

    Phil Hobbs

    On that basis, with 200 ft/min flowing across both sides of my 4"
    square plate, I get just around 1 K/W. Sounds optimistic, but I'll try
    it.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)