[RE-wrenches] DR2424 inverters charging poorly: three units in two days!

Fri Aug 20 13:35:43 PDT 2010

Just a note, FYI
The GFCI will work without a ground, it operates when the current is different between the Hot and the Neutral 

If the generator does not ground the neutral it is supposed to be grounded on the service or what ever is using the power.  The honda inverter generator may not have any conductive surfaces.  Indeed I would like to see a ground on the neutral and the generator frame connected together.  Here in MN we had an accident where a person was killed touching a generator frame.  

The buck boost transformers I use a lot are the 120-240 (or 208)  they are usually about 1kW they have an Output of 16 or 32 volts the secondary is put in series with the line and either bucks or boosts the voltage.  If for example you had 120,240 you would put each 120 on each primary and the neutral would be the common connection.  If the secondary was connected to buck, you would have 240 -32 = 208 volts.  the neat thing about it is that a 1 kW buck boost can produce power for 7.5 kW approximately.  So the Buck boost transformer only carries about 1/7 the load,  and you need a 1/7 the kW in the transformer that you need in the generator or the inverter.  In your case if the gen is about 3.5 kW you couls use a 500 watt Buck boost.  

Darryl

--- On Thu, 8/19/10, Brian Teitelbaum <bteitelbaum at aeesolar.com> wrote:

From: Brian Teitelbaum <bteitelbaum at aeesolar.com>
Subject: Re: [RE-wrenches] DR2424 inverters charging poorly: three units in two days!
To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
Date: Thursday, August 19, 2010, 10:03 PM

Kent, 

Thanks for that info. 

Have you tested for voltage between the L1 and ground while the
generator is running, or just tested for continuity between neutral and ground
when not running? 

I wonder how much Honda paid the City of LA for that sticker J 

Brian Teitelbaum 

AEE Solar 

From:
re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Kent
Osterberg

Sent: Thursday, August 19, 2010 7:51 PM

To: RE-wrenches

Subject: Re: [RE-wrenches] DR2424 inverters charging poorly: three units
in two days! 

Brian,

I also have observed that the Honda EU1000i and EU2000i inverter generators do
not have a neutral-ground bond.  Considering that they are intended as a
portable power system and have a three-prong plug it does seem strange that
there is no bond.  There is also no GFI protection which is normally
required for 15 and 20-amp outlets on portable generators.  But then a GFI
wouldn't work without a neutral-ground bond anyway.  There is no sign of a
UL listing, but mine has a sticker from the City of Los Angeles saying that it
is "approved for use". 

Kent Osterberg

Blue Mountain Solar

Brian Teitelbaum wrote:  

Mick, 

Raising the engine RPM will also increase your frequency above
60Hz, which could injure any electronics running in the house, so be careful
there. 

Allen, 

You mentioned that the inverter/generators have no bond between
the neutral and the frame. I don’t see how they can get away with that
and still have a three-prong receptacle on the unit. Since these are designed
to be portable gennies, they represent a complete power system, able to
directly run loads, and therefore must have a bond. Maybe they don’t have
any kind of over-current protection on them, and if there is no breaker to
trip, the bond is not needed, and they can get away with that. I haven’t
had a chance to play with any of those enough to look that closely. Are you
sure that there is no bond? If so, then this makes them ideal for small
off-grid back-up gennies, on top of the many plusses I knew about. 

Brian Teitelbaum 

AEE Solar 

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org]
On Behalf Of Mick Abraham

Sent: Thursday, August 19, 2010 5:20 PM

To: Allan at positiveenergysolar.com;
RE-wrenches

Subject: Re: [RE-wrenches] DR2424 inverters charging poorly: three units
in two days! 

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.) 

 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? 

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.  

**************************************** 

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.  

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.  

Three poorly charging inverters in two days...plus one Big
Bang...that was not one of my better weeks!  

Mick Abraham, Proprietor

www.abrahamsolar.com

Voice: 970-731-4675

On Thu, Aug 19, 2010 at 6:00 PM, Allan Sindelar <allan at positiveenergysolar.com>
wrote: 

Mick,

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.

The best solutions we have found are the inverter/generators, from Honda,
Yamaha, and now others. Perfectly synthesized sine waveforms and good DR
performance.

Cheap generators are no bargain.

Allan 

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 

On 8/19/2010 5:48 PM, Mick Abraham wrote:  

Greetings, Mechanics~ Please review my problem du semaine
and chime in if you are so inspired.  

My prior experience with the DR series Trace inverters could
be summed up in two words: practically bombproof!   

(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".) 

Last month I visited two customer sites right after one
another. Site #1 has a single DR2424, 120  volts from the portable
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. 

Site #2...the very next day...has twin DR2424 units, similar
OK voltage from the portable 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.  

******************************************************** 

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.  

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... 

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.  

***************************************************** 

I'm writing the Wrenches to ask: 

Can anyone point to the likely problem on these three
machines? 

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. 

Failing a local repair, does anyone remember the flat rates
for repairs by the authorized fix it shops? 

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. 

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.  

Thanks all around. The Wrench List is the Bomb, but with no
loud percussive effects! 

Mick Abraham, Proprietor

www.abrahamsolar.com

Voice: 970-731-4675 

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