Trace SW FET damage [RE-wrenches]

Wed Aug 9 09:43:38 PDT 2000

I know this is a rather long post but I thought I'd let you all know the
current state of my dealings with Trace concerning the damaged FETs and
genset overvoltage conditions.  If anyone else has any ideas as to how such
damage could occur I'm all ears, especially in light of Pat Kiernan's
getting much the same information from a Trace tech on FET damage as I did
originally.

The series of posts included here are in "bottom up" format
#################################################################
Geoff,

That is all rather fascinating.  The unit arrived yesterday in good shape
(no box damage) though I haven't unpacked it yet.  I have to wonder what
could have "corrupted" the data on the oscilloscope that I used for only the
load pattern that was out of spec and not the rest of the data that showed
in spec.  Any ideas on that?  Since you seem to feel that the problem is on
my end I would certainly appreciate any suggestions you might have as to
what could have caused the condition to show up on the unit or the
oscilloscope at that particular load.  It would give me some help in
troubleshooting the problem at my end, if there is one.

Also, I have never gotten a good answer as to what could have caused the
extensive FET damage to my original unit.  If, as you say, the generator
couldn't do it, and the FETs are so well protected, how could they have
become damaged?  I'm certainly not doing anything out of the ordinary with
my system.  It is installed correctly, grounded correctly, and never loaded
too heavily.  So what could have caused it?

Also, I just noticed on the Wrench list that a Wrench had gotten essentially
the same information as I had from one of your techs, i.e. that the damaged
FETs were due to an overvoltage on the AC input.

Thanks for checking out my unit, I appreciate the help with this.

Looking forward to hearing from you.

Tom Elliot
Guffey Energy Works
Solar Energy Education
http://www.wagonmaker.com

----- Original Message -----
From: "Geoff Levin" <GLevin at traceengineering.com>
To: <telliot at wagonmaker.com>
Cc: "Ezra Auerbach" <ezra at island.net>; "Christopher Freitas"
<CFreitas at traceengineering.com>; "Steve Higgins"
<SHiggins at traceengineering.com>; "Nick Klein" <NKlein at traceengineering.com>
Sent: Monday, August 07, 2000 10:51 AM
Subject: SW inverter return

> Tom,
>
> The unit that you sent back for evaluation (Serial # W12975, RMA #
23953-1:
> AC output problems based on the data that you submitted to Ezra) has been
> thoroughly tested by the ENTIRE warranty department.  The reason for this
is
> that no matter how hard any of the technicians looked, there were no
> problems found with the unit that you sent back.
>
> The waveform produced (under both resistive and inductive loads) is normal
> to a SW inverter - not like the captured data that you originally sent.
> This means several things:
>
> 1)  This unit has gone through your "run out of fuel" charging cycle - and
> operates within normal operating parameters - this supports my earlier
> statement that although we do not recommend this approach for battery
> charging, the inverter will disconnect upon poor power output from the
> genset - and should be OK.
> 2)  The data that you took is apparently corrupted - we used several
> calibrated oscilloscopes on your SW inverter in the warranty department
labs
> - with normal waveform produced under a variety of loading conditions.
> 3)  The "hum" that you describe on the AC line may very well be caused by
> circumstances outside those of the inverter.  For example - have you ever
> tried to use your headset and microphone right BEFORE (not after) you
charge
> your batteries, or during different AC loading conditions - hum can be
> caused by things other than the inverter....
>
> The inverter has already been shipped back to you, so you should be
getting
> it within the next few days.
>
> Geoff Levin
> Regional Director,
> Northeastern United States
> Distributed Residential and Commercial Markets
> Xantrex / Trace Engineering
> Email: glevin at traceengineering.com
> Website: www.traceengineering.com
> Tel: (781) 440-0063 or (360) 435-8826  x4053
> Fax: (781) 440-0789
>
>
>
> -----Original Message-----
> From: Tom Elliot [mailto:telliot at wagonmaker.com]
> Sent: Thursday, June 29, 2000 3:54 PM
> To: Geoff Levin
> Subject: Re: SW4024
>
>
> Geoff,
>
> OK here is the scoop on my system as it currently stands.
>
> The serial number on the SW is W12975.
>
> Battery bank is 1050 amphours and was installed in 1994.
>
> The system powers a typical home installation which you can see, along
with
> pictures, at www.wagonmaker.com .  The installation has been upgraded
since
> the pictures on the website to include an RV Power Products Solar Boost 50
D
> in place of the Omnimeter for charge control.
>
> AC loads run are, Vestfrost freezer, Vestfrost refrigerator, occasional
> power tools (chop saw, 10" table saw, circular saws, drills, sanders,
etc.),
> TV, satellite dish, home entertainment center, 2 laptops and 1 desktop
> computer (seldom simultaneously) and we use Phillips compact florescent
> light capsules for lighting (only intermittent use of incandescent bulbs
for
> short duration lighting.
>
> All AC wiring in the house is 12-2 w/ground, wiring from the genset to the
> inverter is 10 AWG wired to AC2 in.  The genset is a Generac 10KW electric
> start unit that is less than 4 years old and has less than 400 hours on
it.
>
> DC wiring for the batteries and inverter are 00 battery interconnects
> (series and parallel cabling) and 0000 cable from the batteries to the
> inverter with cable length of 6 feet.  Batteries are isolated in their own
> box and the power system is in a dedicated space that is 6' x 8' with a 12
> foot peak ceiling.  Plenty of air clearance around inverter with no
> obstructions.  The entire system is grounded to multiple ground rods
bonded
> together with all system grounds including a comprensive lighting
protection
> system.  We have sustained no lightning strikes in 6 years.  Wiring for
the
> PV is all #6awg at less than 60 feet.  There are two separate arrays of
600
> watts each with their own wiring runs to the charge controller.
>
> Hope that helps.  My suspicions are that allowing the genset to run out of
> gas caused the overvoltage that damaged the FETs.  I have talked to a
friend
> who is quite knowledgeable about such things and he felt that you might be
> cutting it a little close using 200 volt FETs and might have protected
from
> this by using 400 volt FETs.
>
> Basically, our original unit, which was recently rebuilt, (RMA #21102-1
Ken
> Ripley) was replaced by the current unit at time I sent the original back.
> When I installed the current unit I did some admittedly simple tests,
> basically I went to my computer and tried to use my headset and microphone
> to record.  Previously, on my original unit, I had lots of hum through the
> microphone and couldn't make recordings on the computer.  When I tested
the
> current unit after installation, I had virtually no hum.  However after I
> put the unit through a charge cycle using the genset (letting the genset
run
> out of gas, prior to my conversation with the tech which indicated that
this
> wasn't a good idea) I began to notice a hum again on my microphone.  The
> data I sent you reflects the condition of the current unit after a genset
> out-of-gas condition.
>
> I run my system with 1200 watts of PV and because of our location in the
CO
> mountains, we don't have to use the generator much for charging, probably
25
> hours a year.  Our average daily power consumption is 3.5 to 4.5 kWhrs, of
> which about 2 is for the freezer and fridge.
>
> We pump our water with a Shurflo DC well pump and pressurize with a DC
> pressure pump (a Dankoff pump) so we don't have any heavy power usage for
> well pumping.
>
> Hope that gives you enough information.  Please let me know if you need
> more.
>
> Thanks for your help.
>
> Tom Elliot
> Guffey Energy Works
> Solar Energy Education
> http://www.wagonmaker.com
>
>
> ----- Original Message -----
> From: "Geoff Levin" <GLevin at traceengineering.com>
> To: "Tom Elliot (E-mail)" <telliot at wagonmaker.com>
> Sent: Wednesday, June 28, 2000 9:11 AM
> Subject: SW4024
>
>
> > Tom,
> >
> > I have received your data files and believe that the SW is not working
> > correctly.  Can you fill me in with some history and the application?
> >
> > I believe when we spoke, you had a genset hooked up as well, can you
give
> me
> > the specifics on the genset as well?
> >
> > Specifically, I am looking for:
> >
> > SW4024 serial #
> > AH of battery bank, age of battery bank
> > typical AC loads run from SW
> > AC and DC wires runs and cable thicknesses (approximate)
> > Installation specifics inside mounting, enclosed in a cabinet?
> > AC genset kW rating, manufacturer and age...
> >
> >
> > Geoff Levin
> > Regional Director,
> > Northeastern United States
> > glevin at traceengineering.com
> >
> > Trace Engineering - Boston
> > 2806 Village Road West
> > Norwood, MA 02062
> > 781.440.0063  Phone
> > 781.440.0789  Fax
> >
>
########################################################################
Tom Elliot
Guffey Energy Works
Solar Energy Education
http://www.wagonmaker.com

- - - - - - -
To send a message:
 RE-wrenches at topica.com

The archive of previous messages: 
 http://www.topica.com/lists/RE-wrenches/

To unsubscribe send a message to: 
 RE-wrenches-unsubscribe at topica.com

To check out the other RE-Wrench participants:
 www.mrsharkey.com/wrenches/index.html

Hosted by Home Power magazine: 
 www.homepower.com

For info contact list moderator by email:
 michael.welch at homepower.com
___________________________________________________________
T O P I C A  The Email You Want. http://www.topica.com/t/16
Newsletters, Tips and Discussions on Your Favorite Topics