Speed contol of AC motors

I have a variety of tools driven by single phase AC motors. Most seem t
be powered by variants of the Crompton motors with a large capacitor o
the side.
I want to control their speed rather than use different gearings via belts. Can I just hook up a single phase to single phase frequenc converter or is life going to be much more complicated?
Robin S
-- rss ----------------------------------------------------------------------- rsss's Profile: http://www.rcgroups.com/forums/member.php?up10 View this thread: http://www.rcgroups.com/forums/showthread.php?tA760
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
rsss wrote:

Robin,
Life is will be much more complicated, or at least expensive. Much has been written about single-phase motors & variable-frequency drives: check google groups for VFD & single-phase motor, there're far too many points to repeat in full here.
It boils down to not being worth the hassle: having to start at full speed then reduce because of high start current, significant lack of torque at low speeds (the worst feature), increased motor hum, minimum speed limited by the presence of a centrifugal starter switch, and burning-out the starter winding by using it too much. Additionally, I've never seen a 1ph VFD - they generally have 3ph outputs, so getting one to use just 1ph of these is crazy.
If you want variable speed, get VFD's and 3-phase motors. If this is too expensive & you don't care about going deaf, use reclaimed commutator motors from washing machines, with a phase-control speed regulator circuit (search http://gb.espacenet.com for patent JP9331689) and some big poly-V belt pulleys.
HTH Guy
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Try Newton tesla www.newton-tesla.com

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Can't be done with AC single phase motors. You need to switch to 3 phase to be able to fit an invertor.
-- Regards,
John Stevenson Nottingham, England.
Visit the new Model Engineering adverts page at:- http://www.homeworkshop.org.uk /
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.