Re: inverter problem and current limiting
From: legg (legg_at_nospam.magma.ca)
Date: 12/07/04
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Date: Tue, 07 Dec 2004 19:04:37 GMT
On Tue, 7 Dec 2004 17:09:22 -0000, "Dave Moore"
<dave.m.moore@baesystems.com> wrote:
>> A 1500W surge rated inverter hooked up to a good battery with low
>resistance
>> connections should have no trouble juicing up a little laptop power
>adapter.
>
>Yes, that's what I would have thought. 1500W at 240V should provide a surge
>current of 6Amps!. However, the inverter documentation doesn't say for how
>long this power can be maintained. The laptop adaptors appear to have a
>large capacitance - when power is removed from them, the LED remains lit for
>30-40 seconds before fading. I suspect that there's a sillllmount of
>capacitance in the laptop adaptors and that when it is connected, it draws a
>large current for a significant time before reaching a'steady state'
>situation. If I could limit the current for this period then I think I could
>avoid the inverter shutting down. Trouble is, I don't know how to do this.
Lower-powered adapters are cost critical, and there is a tendency to
drop such expensive features as inrush limiters. As the input
capacitor is typically less than 100uF, and the CM choke has series
resistance, the peak surge for 110V/60Hz applications can still be
under 30A. At 240V, the economy would be misplaced.
As this isn't a feature required by safety agencies, however, it could
conceivably have been neglected in your model. It should be specified
in the product's literature, somewhere.
These units are often sealed, with instructions refering the end user
to qualified service personnel with a threat of a voided warranty if
opened. Any fiddling or modification will obviously be at your own
risk - which could be considerable.
I know it sounds lame, but the best way to tackle this is to complain
to both manufacturers (inverter and adapter) and vendors, with
pertinent details and model/serial numbers. Replacing the cheapest
part, in the mean time, preferably with a different model/mfr might
make the problem go away while the system grinds towards whatever
conclusion is possible.
You might also consider listing the incompatible model numbers here,
for a start, (and where you purchased them) until the problem is
resolved to your satisfaction. They might ring a bell with other
readers.
RL
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- In reply to: Dave Moore: "Re: inverter problem and current limiting"
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