On Fri, 3 Nov 2017 12:40:20 -0400, "Jim Wilkins"
wrote:

"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.

So do you hear the hiss when on grid power? Could the resiliency of
the rubber hose bypass the function of the unloader? I haven't seen a
crossection of the valve, or had one apart, so I'm not certain how it
works. It sounds like there may be a spool in there which opens the
check valve to allow filling, and it then releases the valve and
covers the orifice/uncovers the vent orifice when the pressure switch
turns off the compressor motor.

If it's only affected after a power outage, could the start cap on the
motor be leaking down?


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.

I finally bought one of those 12v jobs. Haven't had a flat for 30
years, but the time-before-last when I did, the spare was down. After
that, I regularly thumped the spare to verify air. Now, my Tundra
spare and the 4 on the ground have pressure sensors. Handy!

--
The Road to Success...is always under construction.
--anon