Re: AC motor speed control question

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Gregory Hunter" <ghunter31014-at-yahoo-dot-com> 

Michael,

Terminology mistake? Your stated goal of building a
speed control for a synchronous gap is a paradox.

The SRSG depends on the speed NOT varying any--not
even a little. Otherwise, it wouldn't be synchronous.
However, it is possible to build a phase shifter using
a variac and an appropriately sized capacitor. This
allows the operator to remotely sync the gap with the
AC sine wave for best performance. Is this what you
had in mind?

The ARSG on the other hand, does require an external
speed control. If you base the async rotary on a
so-called "universal" motor (angle grinder, electric
drill, electric weed-eater, vacuum cleaner blower,
etc.), you may vary the speed using a variac or even a
cheap lamp dimmer. With such an arrangement, there's
no need to worry about surges, spikes, or other
weirdness. Just plug it in and adjust the speed to
your liking.

Best Regards,

--- Tesla list <tesla-at-pupman-dot-com> wrote:

 > Original poster: "michael curtiss"
 > <lucknau-at-yahoo-dot-com>
 >
 > Hi all,
 >
 > I accidently sent a blank email as my first post
 > ever
 > to this group.  My apologies.
 >
 > I'm building an SRSG, and want to make a speed
 > controller circuit for my AC motor.
 >
 > What I've been reading is that there's a danger of
 > kickback spikes when trying to vary AC current with
 > something like a variac.  There're a lot of
 > references
 > out there to a motor speed control circuit on John
 > Freau's site, but the link no longer exists.  I'm
 > wondering if anyone knows of a good way (and/or
 > schematic) to safely vary the speed of an AC motor.
 >
 > thanks,
 > Michael Curtiss
 >
 >
 >


=====
Gregory R. Hunter

http://hot-streamer-dot-com/greg