[RE-wrenches] DR>FX Compatibility Problem

[Allan Sindelar]

Wrenches,

Here's one that has me quite stumped, and perhaps one of you esteemed
Wrenches has an answer or suggestion.

 

In 2000 we installed a clean, basic budget off-grid system in a new remote
manufactured home for a client, a single woman who lives quite consciously
and frugally. The system was 24V, 600W of PV, Trace DC175, DR2424 inverter,
Solar Boost 50, eight golf cart batteries and a Tri-Metric, along with a Sun
Frost RF16 and Staber washer. The system had worked perfectly for her, and
we replaced her batteries with same last year. 

 

She called a couple of weeks ago because her life situation had changed and
she now worked from her remote home using cell phone and satellite internet.
The new satellite equipment had been troublesome and had already been
replaced, but would still shut down intermittently. Given that she had
already replaced the electronic equipment with same, I suggested that she
finally was facing the problem of modified-square wave DR waveform. I said
that while there were no guarantees, a switch to a sine wave inverter would
likely cure the problem.

 

On Friday I removed the DR and installed an Outback FX2524T. No other
changes, other than longer 2/0 cables. I changed a few settings for flooded
batteries and her generator using a service-truck Mate, but did not sell one
with the system. Everything booted up properly, job done, let me know how it
works out.

 

Friday evening she called with no power. The red "error" LED was lit. I had
her reboot the inverter with the DC breaker, and all was restored. The only
thing she had run was the Staber washer. I assured her that the inverter
could handle a DC reboot without trouble. The next day (yesterday) she left
a message that she had six times overloaded while completing the wash load
with the Staber. Everything else was fine.

 

On Monday she will call for an explanation of what is happening and advice
on how to correct it, and I won't have any. What would allow a Staber to run
fine on mod-square DR power, but overload an FX of the same capacity? The
Staber was likely ordered with notification of the need for a mod-square
control board, as they instructed in the early days, but I wouldn't expect
it to be incompatible with sine-wave AC. 

 

Not having expected this problem, I didn't go hunting for problems such as a
ground fault in the washer circuit. I haven't done any troubleshooting, of
course, but would like to have some idea what to look for. The only anomaly
that I noticed was that some of her Tri-Metric program settings had changed
from what I checked when I replaced the batteries: CEF of L98 instead of H97
meant she always showed 100%, and a couple of other settings weren't what
they should have been. I noted this and reset it, but considered it an
unexplained glitch, as though a nearby lightning surge had scrambled some
settings without damaging anything, or she had inadvertently pressed the
wrong button sequence and changed settings. Now I'm wondering about
extraneous things: a bad ground? Mice chewing through the laundry circuit
(although she has cats.)?

 

What would cause an overload to be detected by the FX that wouldn't have
tripped the DR all these years?

 

All ideas and solutions would be appreciated. I will likely have to make a
return trip, not under warranty, though.

 

Allan Sindelar

Allan at positiveenergysolar.com

NABCEP Certified Photovoltaic Installer

EE98J Journeyman Electrician

Positive Energy, Inc.

3201 Calle Marie

Santa Fe, New Mexico 87507

505 424-1112

www.positiveenergysolar.com

 

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