SW-4024 blowing well pumps [RE-wrenches]

[Steve Willey, Backwoods Solar]

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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