SW-4024 blowing well pumps [RE-wrenches]

[Ezra Auerbach, Trace Engineering]

Hi All,

I think Steve is on the right track with regards to this pump.  Another
variable which could affect pump performance, and thus it's ability to get off
the start winding is what kind of pressure the pump is starting against.  A
heavy column of water or a bunch of pressure stored in the tank will make a
pump work harder.  I had to add a capacitor to my pump because my old U series
would start it when there was no pressure in my tank, but not against 20 psi on
the second start up. As soon as the capacitor went in the pump started every
time.

Ezra Auerbach


"Steve Willey, Backwoods Solar" wrote:

> Since a 1/2 horse is close on a 2500 watt, it is possible that a particular
> 1 horse pump will be at the threshold of surge for the SW4024. Especially
> with added losses in the transformer step-up.  If the inverter is marginally
> able to start this pump it may run on the start winding too long. Start
> windings are only made for intermittent duty, and usually will pop an
> internal breaker if held on past a few seconds but could
> cause the burn-out problem. Just to be sure this is not happening, you might
> watch the
> pump on a clamp on ammeter to see that when it starts the start surge does
> indeed switch out after the rpm picks up.  Try this at both high and low
> battery voltages, and with other appliances on simultaneously that could rob
> enough reserve surge power to prevent the pump getting out of start winding.
>
> I am aware that larger than 1 horse pumps have been run fine on 4024
> inverters. But there are several things that could put this over the line.
> One is differences in starting methods and surge characteristics, for
> instance be particularly suspicious of it if the pump is one without an
> external start capacitor and switching box. The transformer is another and
> additional simultaneous loads are another.
>
> Steve Willey   www.backwoodssolar.com
> Backwoods Solar Electric Systems
>
> ----- Original Message -----
> From: Windy Dankoff, Dankoff Solar <windy at dankoffsolar.com>
> To: <RE-wrenches at topica.com>
> Cc: Adi <adibett at plateautel.net>
> Sent: Thursday, August 03, 2000 4:01 PM
> Subject: SW-4024 blowing well pumps [RE-wrenches]
>
> > Gentlemen,
> >
> > We have a dealer whose customer has blown 3 well pump motors.
> >
> > He has an SW-4024 properly installed. Pump is 1 HP 230V run thru a
> > T-240. He has an Onan generator backup on propane.
> >
> > No other appliances have blown, though he has relatively few.
> >
> > I suppose it could be that blown FET problem that you've been
> > discussing. The dealer doesn't have an RMS voltmeter (yet) but he
> > will now get one. Do you guys think that the known FET problem will
> > be indicated by a high RMS volt (ie. 140V) reading with some
> > consistancy? Or only under certain conditions? Any specific test
> > suggestions?
> >
> > I'll find out later whether his generator ever ran out of gas.
> >
> > Has this problem ever been traced to lightning/static?  -- likely
> > from DC or AC end?
> >
> > Thanks,
> >
> > Windy Dankoff
> >
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