I knew Allan S. & Brian T. would be among the first to chime in with helpful observations. My recollection, however, was that prior efforts with portable generators had worked OK with DR sets...and I know of one setup like that which is working OK in my home county for sure. (That's a portable with fairly big wattage rating, however.)<div>
<br></div><div> I increased the engine RPM on that newly repaired generator but I felt creepy around 125 volts per leg. No more fireworks, please, but should I tweak it up faster?</div><div><br></div><div>So...Allan is saying that he suspects these DR units are operating "normally" and therefore could not be helped by a repair. I look forward to receiving additional posts on this topic. <br>
<div><br></div><div>****************************************</div><div><br></div><div>Brian T's point (about the neutral usually being bonded to metal frame on portable generators) is well taken. I tried to buzz it out with my continuity meter and read "open" between genset neutral & metal chassis. This was at the end of some hot & hectic overwork, however, so maybe I screwed up on that test...loose meter cable or sketchy switch position on the meter, maybe. I will test that again next time. </div>
<div><br></div><div>Although it's a portable genset of fairly low price, I think it has some fancy electronic ground fault interrupter or maybe even electronic ground switching. Perhaps that's why it wouldn't buzz out when the engine was off. When the "green wire" on the twist lock power cord was connected to the metal of the Power Panel System--as seems quite reasonable--the generator's voltmeter would drop to zero as soon as the twist lock plug was inserted. That's when they called me...to boldly go where no normal, sane electrician ever would. I loosened off that green wire from the Power Panel and all looked well. I should have stopped there. The manual for the generator was no help at all. </div>
<div><br></div><div>Three poorly charging inverters in two days...plus one Big Bang...that was not one of my better weeks! </div><div><br clear="all">Mick Abraham, Proprietor<br><a href="http://www.abrahamsolar.com">www.abrahamsolar.com</a><br>
<br>Voice: 970-731-4675<br>
<br><br><div class="gmail_quote">On Thu, Aug 19, 2010 at 6:00 PM, Allan Sindelar <span dir="ltr"><<a href="mailto:allan@positiveenergysolar.com">allan@positiveenergysolar.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div bgcolor="#ffffff" text="#000000">
Mick,<br>
You have missed one fundamental point: The DR (and earlier Trace
mod-square series) gulp only the peak of the AC supply waveform when
charging. They need 164V AC at the peak of the waveform at rated
charging load to supply full rated DC current. A small dip in AC
peak voltage results in a disproportionate loss of DC charging
current. You identified the source of the problem when you
identified the gennies as portable units. Cheap generators provide a
120V AC RMS voltage, but the waveform is flat, with a low peak,
especially under load. This is described somewhere in the DR
manuals, I think.<br>
<br>
The best solutions we have found are the inverter/generators, from
Honda, Yamaha, and now others. Perfectly synthesized sine waveforms
and good DR performance.<br>
<br>
Cheap generators are no bargain.<br>
Allan<br>
<br>
<div>
<div>
<p class="MsoNormal"><span><b>Allan</b></span><b> Sindelar</b><span style="font-size:10pt"><br>
<a href="mailto:Allan@positiveenergysolar.com" target="_blank"><span>Allan</span>@positiveenergysolar.com</a><br>
NABCEP Certified Photovoltaic Installer<br>
EE98J Journeyman Electrician<br>
<b>Positive Energy, Inc.</b><br>
3201 Calle Marie<br>
Santa Fe, New Mexico 87507<br>
<b>505 424-1112</b><br>
<a href="http://www.positiveenergysolar.com/" target="_blank">www.positiveenergysolar.com</a></span></p>
</div>
</div><div><div></div><div class="h5">
<br>
On 8/19/2010 5:48 PM, Mick Abraham wrote:
</div></div><blockquote type="cite"><div><div></div><div class="h5">
<div>Greetings, Mechanics~ Please review my problem du semaine and
chime in if you are so inspired. </div>
<div><br>
</div>
My prior experience with the DR series Trace inverters could be
summed up in two words: practically bombproof!
<div>
<br>
</div>
<div>(There was one time...way back in the day...when a barely
broken in unit stopped charging with adequate amperage,
and...thinking...there was some screwy behavior on the LED
indicators and maybe something else. That issue was resolved
under warranty and was declared by Trace tech support to involve
the "triacs".)</div>
<div><br>
</div>
<div>Last month I visited two customer sites right after one
another. Site #1 has a single DR2424, 120 volts from the <b><i>portable</i></b>
generator, transferred fine...no problems...but would only
deliver a puny five amps to the battery, regardless of tweaks to
the "battery size" & "charge rate" knobs.</div>
<div><br>
</div>
<div>Site #2...the very next day...has twin DR2424 units, similar
OK voltage from the<i><b> portable</b></i> genset, similar
normal seeming behavior, series stacking cable in place, but a
similarly puny DC amperage delivery to the battery. This pair
was slightly higher on DC amperage...about 7 amps per unit.
Tweaks had no effect. </div>
<div><br>
</div>
<div>********************************************************</div>
<div><br>
</div>
<div>In fairness to Site #2, some weeks prior...the genset had
been newly purchased and would not maintain output AC when
connected to the inverter pair. I inherited a new set of
customers when nobody else seemed to know what to try. I
ungrounded the generator plug connection and things took
off...and the charging amps were A-OK. Then...as a good safety
minded technician...I grounded from the metal ground lug on the
frame of that generator to the client's ground rod and the
otherwise routine service call became much more exciting. </div>
<div><br>
</div>
<div>BANG-I fried something in the generator...voltage regulator,
maybe. Then I remembered why I try to never help out on
equipment purchased elsewhere. I broke my own rule...</div>
<div><br>
</div>
<div>After an intense conversation with the generator supplier,
the service guy agreed to fix the genny--"one time and never
bring it back". When it came time to re-connect the repaired
generator, my new customers wanted me to be there. I thought
that would all be ho-hum so long as we left the frame ungrounded
but then I observed the low charger performance. Now I suspect
that something about the generator flame-out also blew important
items in the inverter pair. </div>
<div><br>
</div>
<div>*****************************************************</div>
<div><br>
</div>
<div>I'm writing the Wrenches to ask:</div>
<div><br>
</div>
<div>Can anyone point to the likely problem on these three
machines?</div>
<div><br>
</div>
<div>I probably can't fix this myself but perhaps could be
encouraged to try...somebody on Ebay is selling "FET boards" for
the DR2424 inverter. Inspiration, anyone.</div>
<div><br>
</div>
<div>
Failing a local repair, does anyone remember the flat rates for
repairs by the authorized fix it shops?</div>
<div><br>
</div>
<div>OR: if any List participants have a matching inverter in
inventory...or two...or three...perhaps they could contact me
off list with pricing, etc. Neither client is likely to have the
cash for new TR-2424 inverters.</div>
<div><br>
</div>
<div>Oh, yes...if any could offer a Big Bang theory, that would
help with my education. The neutral on that portable generator
is isolated from ground, so the metal frame should be a
non-participant in any electrical activity on the AC side of
things. The metal frame is...thinking...connected to the
negative of the 12v cranking battery so maybe that's a clue. The
ground rod to which I connected is also connected to the
negative of the 24v house battery and also is connected to AC
neutral from the Trace Power Panel. </div>
<div><br>
</div>
<div>Thanks all around. The Wrench List is the Bomb, but with no
loud percussive effects!<br>
<div><br clear="all">
Mick Abraham, Proprietor<br>
<a href="http://www.abrahamsolar.com" target="_blank">www.abrahamsolar.com</a><br>
<br>
Voice: 970-731-4675<br>
</div>
</div>
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