"Larry Jaques" wrote in message
...
On Thu, 2 Nov 2017 22:15:02 -0400, "Jim Wilkins"
wrote:

I have a 5.5HP, 3750W generator that struggles to start a 1/2 HP
motor
on an air compressor, as long as the tank pressure is low. I can't
measure the compressor motor's torque vs RPM curve but it clearly is
drawing that much electrical power at startup.

That's a 10x start-load! I've read that motor startup uses 4-10x
the
current, but most I've seen were closer to 4x. That's a biggie.

Have you tried an idler pulley setup to remove the flywheel load
from
the motor on startup?

Is it time to plumb in an unloader/pressure switch, or does it
already
have one? http://tinyurl.com/yb6f8hgu

Any way to wire in a start cap to help with the current onrush?

Have you verified the genset specs under load?

Are you trying to fix this, or is it posted here only as info, since
the genset does start the compressor?

The compressor motor has a starting cap.

I replaced the 1970's Load Genie unloader and swapped the copper tube
that may have been stressing it for rubber power steering hose rated
175PSI, 302F but still don't hear the hiss of it unloading, however
the compressor works fine on grid power. I only noticed the no-start
during a long power outage.

If I have to inflate another tire on someone's neglected generator
during an outage I can loosen the head outlet fitting or use the 12V
compressor from the car.

-jsw