On Thu, 10 Dec 2009 16:15:41 -0500, "Stormin Mormon"
wrote:

Can't remember if it was this list. The question was raised,
does compressor amperage decrease as pressure increases. I
set up an informal test, using equipment on hand. Plugged in
a Kill A Watt meter, and set it to read watts consumption.
Plug in my 3 HP Harbor Freight pancake compressor.

I turned on the compressor, and noted the reading as the
pressure went from 0 PSI to 100 PSI. The readings are as
follows:

PSI -WATTS
10 - 198
20 - 199
30 - 211
40 - 220
50 - 229
60 - 233
70 - 237
80 - 240
90 - 255
95 - 248 (wasn't sure the compressor would make it to 100)
100 - 250

Hope the information is of some use to someone. If nothing
else, it used a few minutes of my afternoon.


A couple weeks ago I put my killawatt on my compressor. I noticed
that the amperage went up for a while but toward the end of the cycle
it went down. at the time I thought it might just be from things
"warming up" or perhaps I imagined it but it looks like there is
something to the idea that at sufficiently high pressure the flow
resistance drops faster then the pressure resistance increases.