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[aprssig] Shack backup power

Steve Noskowicz noskosteve at yahoo.com
Mon Sep 12 00:49:00 UTC 2011



Cool!  I'm impressed...

-- 
 73, Steve, K9DCI   USN (Vet) MOT (Ret) Ham (Yet)
--

> All I know is that my 1200W quasi
> sine inverter in my car trunk that I got from PEP boys for
> $120 easily starts my refrigerator.  It also starts
> 5000 BTU ACU units to my unbelievable surprise.
> 
> I think it is because these modern modified sine wave
> inverters have quite a 180 VDC storage capacitor prior to
> the 60 HZ switchers that can provide the several millisecond
> starting current?
> 
> Oh, you are right.  I said generator... and yes, I
> have had problems starting  a refrigerator from a
> generator... but have been amazed at the inverter
> performance.
> 
> ---- Original message ----
> >From: Steve Noskowicz <noskosteve at yahoo.com>)
> >
> > While waiting for the OT police to
> > show up, Steve, K9DCI comments first:
> > RE: Bob's two comments:
> >
> >> ...to keep the refrigerators ... going ... A 1kw 
> >> generator and a can of gas is hard to beat for
> economy.
> >> A typical refrigerator is rated at 400 to 900
> watts
> >> (when running (and defrosting...
> >
> >
> > I say OOPS!
> > What about start-up (locked-rotor).  Having had
> experience designing (350 W DC Brushless and higher variable
> speed A/C motor drives) I'm very aware of locked
> rotor.  I have been using 5-8 times run current to get
> an idea of locked rotor.  I recently learned that there
> is a letter on motors with the locked rotor current factor,
> but don't have a conversion chart.
> >
> >What are typical fridge locked rotor values/fctors?
> >
> >I've only got 1 fridg...
> >Wagging 800 watt, 6.7A run (no defrost and I'm too lazy
> to push it out) and 5-8x start, this amounts to 4000 - 6400
> surge.  Not a triffle.  I'm pretty sure typical
> 1kW gensets won't hack this.
> >
> >For a completely irrelevant example...One of my 400W
> 800W/surge Coleman inverters has to be switched on before my
> boat-anchor HP (141T type) spec analyzer that draws (I just
> measured it - Current clamp) 1.13A or it faults out.
> >
> >Steve, K9DCI
> >
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> 
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