[RE-wrenches] offgrid system question

[Phil Undercuffler]

Thanks Darryl,

For this test we were looking primarily at how the inverters handled the
inrush current of a starting surge, and what affect that would have on
voltage regulation of both the loaded and unloaded phase.  I had heard
anecdotal tales of earlier split phase inverter designs allowing the
unloaded phase to spike wild under starting surges and we've all seen
real world problems with inverters dropping voltage to keep the current
up, so I wanted to see what would happen with the new XW and Magnum
products.  We also had the opportunity to have FX and SW products as a
reference comparison.

We used simple power strips in order to get all the loads to make a
coordinated starting spike, and all surge loads were on one phase.  We
locked the triggers in the on position, then turned on the power to all
the loads with the power strip switch.  Not high tech certainly, but
effective and kept us on time and within budget ;-)  We reached the
limits of the turkey timer circuit breakers in the power strips before
we reached the limits of the inverters or ran out of power tools.  In
future tests, I'll rig up a series of relays to allow us to push the
limits further.

The loads were standard contractor style equipment I hauled in from
home.  

Chop saw -- Dewalt 12" compound miter saw, 15 amp 120v
Planer -- Delta 12" planer, 15 amp 120v 
Routers -- Porter Cable 690's, 11 amp 120v, 1-3/4 hp
Air compressor 1 -- Thomas T-30 pancake, 12.5 amp 120v, 1-1/4 hp
Air compressor 2 -- Rigid stacked hot-dog, 14 amp 120v, but probably the
second ugliest air compressor I've ever seen, from a starting surge POV.

There were also a baseline load on both legs of two electric heaters,
and we had two CF light bulbs for visual feedback -- it's one thing to
look at squiggles on a scope, but sometimes the best feedback is seeing
what is going to happen to the lights.  

Now I'm kicking myself, because we didn't try the same conditions using
grid power.  Oh well, next time.

Battery bank was a single 48v string of 5 year old Surrette S460
batteries, with 4/0 cabling.


Phil Undercuffler
Director, Battery-based and Off-grid
Conergy Sales & Systems, Americas
Our World Is Full of Energy
1730 Camino Carlos Rey Suite 103
Santa Fe, NM  87507
p.undercuffler at conergy.us
Direct | 505.216.3841
Toll Free | 888.396.6611 x4841
Fax | 505.473.3830
www.conergy.us

-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Darryl
Thayer
Sent: Tuesday, August 19, 2008 6:57 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] offgrid system question

Thanks Phill, 
I have often thought that I should have compiled such a list from my
experiances, but of course we are always to busy to do so.  

Could you add a few words to your post
For the chop saw, type & manfactureer, and how was the surge attained? I
assume it is just turning on of the saw no load at switch on? , or was
it the peak as the saw cut onto the log.  

On the others similar and was the surge when one device was turned on?
of the set? or were all turned on together?  

Another interestering datum would be what is the surge currents doing
the same experiments using the grid.
 
Thanks Darryl