Fwd: Trace 4024 and MREF [RE-wrenches]

Thu May 18 12:32:06 EDT 2000

<x-flowed>Hello Wrenches

Anyone got any feedback on this Trace SW4024 problem listed below?

Richard

>From: "Tom Elliot" <telliot at wagonmaker.com>
>To: "Richard Perez" <richard.perez at homepower.org>
>Subject: Trace 4024 and MREF
>Date: Tue, 16 May 2000 15:09:00 -0600
>X-Priority: 3
>
>Richard,
>
>I just had an interesting experience with my original Trace 4024 that I
>thought I'd run by you.
>
>The unit failed one day with a heatsink overtemp condition in the battery
>charger fairly early in the charging cycle (apparently the earlier units
>were not as well protected from overtemping as the current units) that
>corrected itself within 15 minutes.  The unit seemed to be producing power
>OK afterward but since it had failed during a charge cycle and gotten hot as
>hell in the process I sent it back in for a rebuild and upgrade.  I was
>fortunate to have another unit in stock I could use in its place.
>
>When the tech called me to give me the price he told me an interesting story
>about the failure.  It seems all 4 high end FETs had failed (he said the
>board was "obviously burned") and that had apparently contributed to the
>failure in the charger (though I'm not sure what the connection is there).
>When I asked him how that could happen he said that high voltage on the
>charger side could cause it and that generators could easily put out such
>high charges.
>
>It seemed strange to me that if it were such a common occurrence they
>wouldn't have protected the system from it but apparently the FETs are good
>to 200 volts.  It turns out that when a generator runs out of gas (which is
>bound to happen sooner or later with all gas generators) the generator
>spikes the voltage to try to compensate.  When that happens unregulated
>voltages of 200 + are easily possible.
>
>This was apparently when the FETs started to go but according to the tech it
>isn't a catastrophic failure but a cumulative one and there is no indication
>from the unit that such a failure is occurring.  When I asked him what that
>does to the unit he said it basically causes the unit to cease being a sine
>wave and revert to modified square wave (I just can't bring myself to call
>it modified sinewave <G>).  It also reduces the surge capacity but if no
>large loads were being run the reduced capacity would never be noticed.
>
>It strikes me as odd that the unit could undergo such a failure without any
>indication that it has happened and wonder if there aren't a lot of
>"sinewave" 4024s out there that are now acting as mod square wave units.
>The only way we noticed it was when the battery charger failed.
>
>I was wondering if you could do some checking on that and if you might want
>to warn some folks of the dangers of letting generators run out of gas.  I
>have never seen any indication in any of the literature that it was
>something to watch out for and with such devastating results you'd think
>someone would make mention of it.
>
>
>Tom Elliot
>Guffey Energy Works
>Solar Energy Education
>http://www.wagonmaker.com

------------------------------------
Richard Perez
Home Power
PO Box 520, Ashland, OR 97520  USA
Tele: 530-475-3179
FAX: 530-475-0836
Subscriptions: 800-707-6585
mailto:richard.perez at homepower.com
Web: http://www.homepower.com
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