In article , Phil Allison wrote:

"Jeff Thies"
Phil Allison wrote:

I suggest you provide the next replacement for that vulnerable tranny
with
some "protection" - firstly an in-line fuse of say 1/4 amp AND a
capacitor wired across the primary of say 1uF rated for continuous use
across the AC supply.

If there is an overload on the tranny, the fuse will blow.

The 1uF capacitor should suppress spike voltages enough to save the
tranny from harm.

1 uF sounds a little high.

** No it ain't.

I thought you had simply misspoke and that this was an honest error.

The reactance of a 1uF cap at 60Hz is: 2652 ohms (1/(2*pi*F*C)
Online calculator:
http://www.kusashi.com/reactance-c.p...&stage=results

V^2/R = W

Assuming primary, as why would you put it on the secondary:

120^2 / 2652 = 5.43 W

Does that not seem wrong to you?

** Completely.

Such a cap dissipates no energy at all.

What planet do you come from ??

With AC, volts times amps is not necessarily watts.

If determination of volts and amps are both "true RMS", (non-"true RMS"
meters are usually OK for line voltage and for current through a cap
across an AC line),

then volts times amps is "volt-amps". Ratio of power consumption (in
watts) to VA is power factor. Capacitors have very low, ideally zero,
power factor.

If not then go buy a 200V non polarized 1uF cap. It is no easy chore.

** 1uF caps for use across the AC supply are cheap and plentiful.

Digi-Key has 3 easy enough to find 1uF ones with X1 or X2 rating, all
$3-plus plus shipping with minimum order requirement to avoid a surcharge.

Among those 3, my favorite is FC233820105, which is by Vishay/BC
Components. Its datasheet refers to 2 UL standards and 2 CSA ones, and has
a link to an application note making a claim that the referenced UL ones are
sufficient for achieving the "UL Recognized" ("backwards UR") mark.

Typical examples are metallised polypropylene " class X2 " types and sell
for $1 or $2 each.

http://search.digikey.com/scripts/Dk...me=399-5466-ND

That one needed me to delve into its datasheet to see that it claims to
meet the two relevant UL standards and that it has X2 rating. Its AC
voltage rating is 275 volts. 91 cents each plus shipping, with a minimum
order requirement to avoid a surcharge.

Any of the 4 capacitors above (2 mentioned specifically) look good, in
the unlikely event what is needed is a capacitor across the line.

What planet do you come from ??

--
- Don Klipstein )