Re: Chargers and Harmonics

["Eric Chang" <ericchang@my-deja.com>]

 Except for the price of the power line filter
and the labor to install it :-).  Actually, the
commercial EV charger that I saw did not have an
input power line filter, and neither did the 
homemade one, and they both generated noise
which was sent back to the power line, so these
filters would help a little bit.  The values of
capacitance and inductance are very tiny in
comparison to the major power carrying harmonics
that one is concerned about in a typical phase
controlled or switching converter.

As a rule, you should stick with the sizes that
Lee or Mark recommend.  This means that a
passive power correction unit will be large and
heavy (about the size of a small suitcase, and
on the order of several pounds).  Effective
capacitors and inductors are not very small.

If cost is your overriding concern, I have been
scoping out construction sites.  They often have
a lot of steel scrap that you can use for
winding a toroidal core, but you are cautioned
that this material will fall far short in 
performance of a commercial silicon steel tape
wound toroid.  Also, the wire that you can often
salvage around these sites is downright
dangerous if it gets hot and is wound too tight.
Finally, I have not seen any capacitors, but I
am no longer in training, so the length of my
journeys is shorter than before.  One
interesting idea is old fluorescent light
ballasts.  Some of these have capacitors, but
due to new industrial standards, the ones you
see discarded or on salvage are the older
electronic type which are not useful in this
application.  One day, I did see a large pile of
old style ballasts that would work, but the
supervisor said that they would cost money (not
much).  Watch out about salvaging old AC motor
capacitors.  The start variety have caused some
unpleasant experiences when subjected to 
continuous duty.


--

On Wed, 30 Aug 2000 21:38:20   ggschaeffer wrote:
>Power line filters are cheaply gotten from industrial surplus dealers
>like  Marlin P. Jones in Florida,  The Electronic Goldmine in Scottsdale,
>AZ  800-445-0697,  B G Micro in Garland, TX  800-276-2206.  I got mine
>from MECI inDayton, OH, 800-344-4465   www.meci.com.  Their new catalog
>lists  a 15A 125VAC, a 15A 250VAC, a 20A 250VAC, and a 37A 250VAC model.
>$5.00 is the most expensive!  Try one, you don't have much to loose.
>Gordon Schaeffer
>ggschaeffer@juno.com



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