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| Ev Archive for March 1999 |
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| 1534 messages, last added Wed Aug 08 18:44:43 2001 |
[Date Index][Thread Index]
Re: Air Conditioning Options
It is a safe bet that a window air conditioner will draw less than 12 amps,
because this is the most UL allows a single appliance to draw from a 120vac
15amp outlet.
You can also bet that the air conditioner is not power-factor corrected; it
will have a power factor around 0.7-0.8. Using 0.75 as a guess, it will use at
most 120vac x 12amps x 0.75 = 1080 watts. Real units will probably be 500-1000
watts.
The power factor can be easily corrected back to 1.0 by adding AC rated
capacitors across the line. This reduces the current load on the inverter,
improving efficiency.
Starting current is VERY high. This is really hell on electronic inverters. I
would be surprised if an inexpensive UPS inverter could handle the starting current.
Consumer air conditioners are designed right to the edge -- no more copper or
iron than absolutely necessary. This means they run right at their maximum
limits even with sinewave power. If you drive them with a square wave, they
are going to be less efficient, and overheat. This may or may not be critical;
the unit may just shut off every 15-30 minutes to cool a bit.
Lee Hart If you would not be forgotten
4209 France Ave. N. Soon as you are dead and rotten
Robbinsdale, MN 55422 USA Either write things worth the reading
phone (612) 533-3226 Or do things worthy of the writing
e-mail XURQ03A@prodigy.com (Ben Franklin, Poor Richard's Almanac)
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