[TowerTalk] Ramp up

[Rick Mainhart]

Hi Andrew,

For three-phase AC motors, you can get variable speed drives ... but they
aren't exactly cheap. They ARE coming down nicely in price from even 5
years ago ... but for 240 volts, three-phase you are still looking at
$500-800. I don't know of anyone making speed controllers for
single-phase motors.

If you aren't using three-phase motors ... you might look for a motor
with a built-in speed controller ... again, not cheap. 


Good luck & 73,

Rick, WB3EXR

On Wed, 8 Nov 2000 19:03:50 +0000 Andrew Williamson
<andrew@gi0nwg.freeserve.co.uk> writes:
>Interesting discussion.  Out of interest, is there an easy (and 
>cheap)
>way to ramp the speed of an AC motor and control the speed it runs 
>at?
>I know inverters can be used, but they are prohibitively expensive.  
>I'm
>asking because we currently use 240V 1/2hp motors on some homebrew
>rotators, but they turn a little fast..... (and yes, the 240V motors 
>are
>run from a residual current trip circuit, so they are fairly safe...)
>
>Andrew Williamson GI0NWG / AC6WI

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