Re: gEDA-user: electrolytic capacitors

[andrewm <andrewm@xxxxxxxxxxxxxxx>]

 >> Someone wrote: 
 >>
 >> [Electrolytics] can explode pretty violently, so
 >> let me tell you a story.  [...785V on a 450v
 >> cap...serious dent in plaster...]
     
 > Robas, Teodor wrote:
 >
 > <SNIP>
 > The resulting flame was always entertaining !
 > Sometimes the ASIC wanted to take all the punch
 > and dig a hole the size of a finger in a 4 layer
 > PCB. The capacitor, only 220uF/50V, survived.


I will second the "silicon and epoxy makes a more
impressive explosion than electro/tants" theory

The one I remember is a TO-220 fet.

I was at a place that made and fixed power inverters
ranging from 12VDC-240VAC units for running a TV up
to 110VDC-415VAC as UPS units for small hospitals.

Behind the shed where the units where tested and
fixed was a bank of lead acid cells.  These cells
were the normal 2V very many hundred amp hour cells
used in solar RAPS.  The battery that was made from
them had multiple taps on it

12v
24v
48v
110v

obviously for testing different voltage inverters.

One day the guy was testing a 12V unit that used
50N05 fets.  No prizes for guessing which tap he
mistakenly used instead of the 12V one.

Anyways - there was 110V across the FETs that are
rated to half that.  The big lead acid batteries
that could make fencing wire do a good impression
of a light bulb.  The test did not last long.

Two legs of the TO-220 package stayed in the PCB.

Most of the epoxy gone.

The metal tab of the TO-220 embedded 10mm into
a besser brick (breeze block) wall 1/2 a meter
behind the unit.

I was five meters away and had ringing ears.





_______________________________________________
geda-user mailing list
geda-user@xxxxxxxxxxxxxx
http://www.seul.org/cgi-bin/mailman/listinfo/geda-user