Re: Electronical question
- From: "DoN. Nichols" <dnichols@xxxxxxxxxxx>
- Date: 27 Sep 2008 00:42:22 GMT
On 2008-09-26, SteveB <toquerville@zionvistas> wrote:
I bought a Trippe Electric 400 watt square wave resistive load only 12v.
inverter at a yard sale. I hooked it up directly to a 12v. battery, and put
in a 110v. test light, the small two prong ones. I flipped the switch, and
couldn't get the test light to come on.
Do I need to hard wire this to the 12v. system? Maybe there wasn't enough
juice in the battery to kick the light on?
What wattage light were you using? Note that an incandescent
lamp tends to draw a *lot* more current when it is first switched on
(lower resistance until it heats up) and thus it might draw too much for
the inverter to start heating.
I did hook it to a 12v. cigarette plug, and promptly burned out the 5 amp
fuse. I put a 30 amp fuse in there, and it burned that out, too.
Well ... assuming 100% efficiency, a 400 Watt load would draw
33.33A from 12 V. You might have perhaps 80% efficiency (if you are
lucky) would would draw 41.66 A.
What does resistive load only mean?
No transformers, motors, TV-sets, computers,, or most other
things you are likely to want to run. You could probably start multiple
smaller lamps, one at a time, to get up near the 400 Watt load limit,
but one 400 W lamp would draw too much current to start off that way.
If you plugged it into the line, and set up switches to switch *very
quickly* from the power line to the inverter you could see whether it
could really support that 400 W load.
and square wave?
It means that unlike the power line, which starts at zero volts,
goes smoothly up to 1.414 times the nominal voltage (so a 120 V line
would peak at 169.6 V, roll over smoothly and start down to duplicate
the behavior below ground (negative voltage) before starting back up to
repeat that pattern until you turn it off. This shape is called a "sine
wave".
This inverter which you have, however, switches very quickly
from -120 V (negative voltage) to the same voltage positive, holds for
1/120th of a second (assuming that it is producing 60 Hz) then drops
very quickly to the same voltage negative, holds and repeats. This kind
of waveform generates all kinds of nasty voltage spikes on the output
side of transformers.
Am I farting in the wind? I need to hook up a laptop in my truck for
business purposes.
A laptop is *not* a resistive load. You will almost certainly
kill it.
Should I just go get the cigarette plug inverter they
sell at the computer store?
Yes -- that should be cheaper than replacing the laptop every
time you connect it and turn it on.
Or maybe you can find a cigarette lighter adaptor to directly
power *that* model of laptop (check what the maker offers), which would
be much more efficient than converting to 120 VAC and then back to the
voltage which the laptop *really* wants.
There are things that this will run -- but don't even *think* of
running a computer from it.
Good Luck,
DoN.
--
Email: <dnichols@xxxxxxxxxxx> | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---
.
- References:
- Electronical question
- From: SteveB
- Electronical question
- Prev by Date: More on odd threads....
- Next by Date: Re: purge a oil tank for safty
- Previous by thread: Re: Electronical question
- Next by thread: Re: Electronical question
- Index(es):
Relevant Pages
|
