RE: Variac blowing fuses (another newbie question)

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Lau, Gary" <Gary.Lau@xxxxxx>

Hi Dennis:

Re. your PFC caps - what does the label on the cap say?  If the uF value
is stated as a range, i.e. 41-53 or 88-108 uF, then it's a starting cap.
For the starting cap that I pictured on my web site, it says right on
the label "For motor starting".  Other starting caps may or may not say
that.  The manufacturer's name by itself is meaningless, as many cap
makers make both starting and run caps.  Also, the description stated in
a catalog may or may not be definitive.  A surplus vendor like All
Electronics is probably not staffed by degreed component engineers,
although Mouser seems to be at a higher technical tier.  But since you
have the caps, probably the most definitive test is just trying it.  A
starting cap will start venting steam in less than a minute if you just
hook up AC power to it.  If yours have been energized longer than that
without getting warm, they're probably OK.

Regards, Gary Lau
MA, USA

-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: Saturday, January 07, 2006 6:08 PM
To: tesla@xxxxxxxxxx
Subject: Variac blowing fuses (another newbie question)

Original poster: otmaskin5@xxxxxxx

Got a lot of great advice on this from you guys.  Just wanted to let
you know how it turnied out.

I added PFC/motor run caps only - & didn't do anything to lower tank
capacitance at this point (that was Plan B).  PFC seeed to take care
of it.  I've run the coil a good number of times for 30-45 second
durations, even with a lot of continuous arcs to ground - and even
though I only had a 15A replacement fuse in stead of the original
20A.  I had no further blown fuses.

PFC alone may not be the ideal solution.  And I may ultimately be
better off lowering my .03uF tank capacitance as suggested by a
number of you (I have a 15/60 NST).  But at least I'm back in the
ozone business for now.

As a side note, when my motor run caps arrived from Mouser, they
looked identical to the picture of capacitors "not suitable for PFC
use" shown on Gary Lau's website.  I thought oh @#%, I got the wrong
ones.  But I checked again, they are shown as motor run caps on the
Mouser shipping order.  And Gary's picture shows the brand name
Phillips, while the ones I goe are DCE.  But they look identical in
every other way.  Anyway, I tried them & they seem to work OK.

Thanks everyone.  Dennis Hopkinton, MA

Now to go to work on those bleeder resistors...