Posted by Eeyore on April 11, 2009, 3:12 am
Johnny B Good wrote:
> Hi Guys,
> I've been wrestling (on and off over the past 6 months or so) with a
> problem regarding standby power when I bought myself a PowerCraft 2,800W
> Dual Voltage Long Run Generator from Aldi about 6 months ago to provide
> extended 'emergency power' over and above the hour or so's worth I can
> get from an APC Smartups 2000 I keep in my basement and was wondering
> whether anyone could help me resolve it.
> I know, being in the UK, that the risk of an extended outage is
> extremely rare, but, in view of the way things are likely to go to pot
> in the next few years,
Caused by the 'greens' you mean ?
> I'd rather be prepared than get taken by
> surprise. That, plus I like the challenge of fixing all those "Broken by
> Design" Technology based 'gadgets'.
> If ever there was a "Broken by Design" piece of technology, the humble
> Petrol standby generator has to be it. From my own (admittedly limited)
> experience, and what I've seen, googling similar issues, and postings in
> this NG over the past year or two, it seems the task of generating a
> simple 50 or 60Hz sinewave 120 or 230 vac supply from a small petrol
> driven generator is beyond the wit of the manufacturers.
A UPS shouldn't care that much about the purity of its input waveform I'd
have thought. Maybe the generator needs a partial load first ?
Can you post a pic of the output waveform ?
At the end of the day, I suspect you'll have to change the UPS or the
genset.
Graham
Posted by Eeyore on April 11, 2009, 3:14 am
Martin Riddle wrote:
> I gather you checked the grounds and such, floating systems always prove
> to be problem stricken.
> You should double check the Frequency spec with APC, I hear they are
> real picky and 54hz sounds too far off.
> Perhaps its HF noise from the field excitor or brushes? Try an ISObar on
> the input to the UPS.
>
http://www.tripplite.com/en/products/product-series.cfm?txtSeriesID „&EID401
> Last resort look in to Common mode filters, they filter diff and single
> ended noise. The chokes are smaller, but you need to pick the right
> approved Cy and Cx capacitor. I think Cy can not be more that 3300pf.
> Coilcraft has a good appnote.
>
<http://www.google.com/search?q=common+mode+filter+design&rls=com.microsoft:en-us&ie=UTF-8&oe=UTF-8&startIndex=&startPage=1>
> A regular power transformer primary is about 15H or so depending upon
> volage.
> I'm sure the secondary is in the 100's mh for a 24volt secondary. You
> could use off the shelf stuff there.
> Even the EI core can be gapped easily.
> Some 10A sec trans can be found here http://www.mpja.com/
An ultra-isolation transformer might help. They cost an arm an a leg though.
Graham
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> I've been wrestling (on and off over the past 6 months or so) with a
> problem regarding standby power when I bought myself a PowerCraft 2,800W
> Dual Voltage Long Run Generator from Aldi about 6 months ago to provide
> extended 'emergency power' over and above the hour or so's worth I can
> get from an APC Smartups 2000 I keep in my basement and was wondering
> whether anyone could help me resolve it.
> I know, being in the UK, that the risk of an extended outage is
> extremely rare, but, in view of the way things are likely to go to pot
> in the next few years,