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Inverters used with gasoline generators?

Discussion in 'Home Power and Microgeneration' started by Karl S, Dec 21, 2006.

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  1. Karl S

    Karl S Guest

    This is more "emergency power" than "alternate power", so efficiency
    isn't particularly important in this scenario:

    A technical installation that consumes lots o' watts, devices on UPS's
    to carry them through short outages...
    A longer outage occurs.
    A good-quality Honda 5KW gasoline-powered generator is brought in, fired
    up, and the UPS's plugged into it... A few hours of operation time
    bought? No. The UPS's don't like the generator's flavor of 60 Cycle AC.
    They ignore the power available at their inputs and continue to run from
    their failing batteries.

    Observing the output of the generator on an oscilloscope shows a smooth
    60-cycle sine-wave. Grounding the chassis of the generator to the house
    power ground corrects an apparent wiring error condition, but does not
    convince the inverters to stop running from their batteries. Connecting
    the output of the generator through an AC powerline conditioner/filter
    helps exactly not at all.

    Much annoyance results.

    Question: are there any UPS's available which will accept the output of
    a portable generator?

    Thanks much.
     
  2. Jim Rusling

    Jim Rusling Guest

    I have an APC XS 1500 that will accept my Generac 4000 generator, but
    only if I set the sensitivity to medium instead of high. I also need
    to have some other load. It will still complain for a few seconds
    when the fridge or furnace starts.
     
  3. Never had a problem with Powerware Prestige dual conversion units -
    but the BEST solution is the old " Best UBS" system from Best Power.-
    meaning unlimitted battery supply. A DC generator running on deisel,
    gasoline, natural gas or propane was connected to UPS units designed
    for extended run (extra battery packs) and automatically started when
    the UPS battery voltage dropped to something like 22.62vdc under load.
    They could (and often did) run for 2 weeks in hurricane territory to
    keep essential services running. Many ambulance and police dispatchers
    used them.
     
  4. _jj_

    _jj_ Guest


    It would be interesting to know what the UPS is seeing
    ... that it doesn't like ...
    .. harmonic ?
    .. fluctuating frequency ?
    Please keep us posted.
    Jt
     
  5. Karl S

    Karl S Guest

    The unloaded output voltage of the generator was 126 VAC, or 300 V P/P
    as seen on an oscilloscope, showing perhaps 5 volts worth of some
    higher-frequency sinewave component on the positive and negative peaks.
    I included that "ripple" component in the 300 V P/P measure. The APC
    line conditioner (I don't recall the model) made no change in the
    voltage or appearance of the waveform. The three UPS's involved were all
    APC models ranging from 500 VA to 1000 VA capacity.
    In another situation, the propane-fueled backup generator for a remote
    site worked properly, but the APC UPS's there would not accept the power
    it provided, except intermittantly when the UPS's sensitivity adjustment
    was set to minimum. I have no spec's at hand for that system, as I am
    currently at home.
     
  6. Karl S

    Karl S Guest

    Now that's the sort of information I was looking for. The name and model
    of an inverter that isn't so fussy about what power it eats. I work in a
    small town, with no local source of UPS equipment beyond what department
    stores and Best Buy provide, so I haven't had much chance to compare
    features. Thanks!
     
  7. Guest

    Another thought is to use a power conditioner to bring the generator
    power closer into line. *note that I'm speculating on this and have
    never done it. I'd be curious to know if there are reasons why it
    wouldn't work.
     
  8. BackUPS or SmartUPS? APC is crap either way, but it would be
    interesting to know. I suspect BackUPS.
     
  9. Like a Sola Ferroresonant voltage regulator? Might work.
     
  10. You

    You Guest

    I would agree with all the others posting in this thread, you don't give
    us much information on just what equipment, you are using. There are a
    whole raft of "cheapie" UPS's sold by all kinds of Office Supply Stores,
    and the like, that just can't deal with ANYTHING but nice Grid Power.
    APS is just like all the rest, if you go "Cheap" you don't get a
    "Quality" unit. For Long Term operations I really like the old Best
    Power FrerroUps's, they weren't cheap, light, or terribly efficent, but
    they DO work and on just about ANY Power source. Of course the best
    UPS's mostly are designed to to operate the Load for a LIMITED time to
    allow for Safe Shutdown of the loads. If you want Backup Operational
    Power, get yourself a nice Diesel Genset with AutoTransfer and a "GOOD"
    UPS, that can handle your loads untill the Genset comes Online. All it
    takes is MONEY, and just a smidge of Brains.......
     
  11. Not much can beat the old Best Fortress line for a unit that is not
    dual conversion. I have 2 fortresses - a 600 and a 1.3, as well as a
    Rowerware Prestige 800. I've also got an APC SmartUPS 1000 - and there
    is no comparison. The SmartUPS has been a lot of trouble, the
    Fortresses have been trouble free except for a set of batteries each
    at about 5 or 6 years. The Prestige just got a set of batteries after
    7 years. I can't remember ever having to replace a Fortree or Prestige
    due to failure, but I've sure scrapped a lot of APC units over 15
    years.
     
  12. Guest

    I'll have to add my 2 cents on the Best products. They seemed to be
    great and I probably still have my certificate from their little
    reseller seminar. Spec'd a couple smaller units, but the customers
    picked up the APC stuff off the shelves of office supply stores
    instead. IIRC, Best was bought out a while back?

    FWIW, I've had good luck with line conditioning from Tripplite. Yeah,
    I know their reputation isn't great, but I stuck line conditioners in
    a couple of locations that were blowing out printer circuit boards
    every couple of months, and totally eliminated the problem. Haven't
    had to replace one in five or six years.
     
  13. Karl S

    Karl S Guest

    Yeah, I checked that later too... I think that old Tektronix
    oscilloscope is getting a little out of vertical calibration. Eh, it's
    not important. The Fluke digital multimeter I checked the AC voltage
    with is pretty new and more likely to be accurate. I was using the
    'scope mainly to look for spikes in the waveform.
    The APC line conditioner called the generator voltage "high", so I'll
    count it as a vote against the 'scope as well.

    Oh, and a "Happy Holidays" to all. I'll be visiting a sister of mine who
    has recently gone through an unexpected five days without electrical
    power. When her power came back on, she emailed:
    (To the tune of "Catch a falling star)

    Find a fallen tree,
    and cut it up for firewood!
    There's a will and there's a way!
    Find the fallen tree,
    That took out all your power,
    It will cook your meals today!

    What a family I was born into...!
     
  14. Fortress was bough out by powerware, which also took over EXIDE. The
    powerware stuff is pretty good again now, after a few years of
    transitional junk. Both my Fortresses are 4 digit.
     
  15. Make that BEST was bought out by Powerware.
     
  16. An inverter generator will NOT be a problem. Running from a
    non-inverter type can cause problems. (frequency and voltage poorly
    regulated, waveform distorted.
     
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