Air Compressor Horsepower/Wattage/Amperage

Good Lord, starting current of 64 amps at 115 volts? Most 15 amp breakers
would pop in half a second at 400% overload; how do these little one horse
compressors plug into a 15 amp circuit and start so easily? It is just when
you don't have nearly infinite current available from house mains and you
start fooling with generators that the situation becomes sticky.

Lessee now, lets go to the 100% (one horse) column and we find at 115 volts
a PF of 79, 66% efficiency, and 15.4 line amps. One horse is 750 watts and
at the one horse level this rascal is sucking 1770 watts, or an efficiency
of 42%. But the table shows a 66% efficiency. Hmmm ... cos (79°) = .2 but
that factor of out of phase isn't going to get me into the ballpark, nor is
the sin at .98 going to get me anywhere either.

Hmmmm ...

Jim

--
"Dream as if you'll live forever. Live as if you'll die today."
--James Dean


"GeorgeB" wrote in message
...
On Tue, 19 Jun 2007 21:09:51 -0700, "RST Engineering"



Load Characteristics at 230 V, 60 Hz , 1 HP
% of Rated Load 25 50 75 100 125 150
S.F.
Power Factor 37 52 64 72 79 83 76
Efficiency 43.4 58.2 64 66 65.8 63.7 65.9
Speed (rpm) 1782 1766 1749 1729 1706 1676 1715
Line Amperes 4.9 5.3 5.9 6.7 7.7 9.1 7.3

ASSUMING 100 psi is 90% load, mayne 6.5A on 230. Restart at 80psi, if
compressor is properly designed, will be no worse than 0 psi start,
ie, it starts briefly unloaded. (It won't draw any more current in
any event, but the starting time would be extended)