On 30 Oct 2020 at 19:37:18 GMT, ""Brian Gaff \" Sofa\)"
wrote:

If he had one why bother with the device, unless its some kind of slow
starter circuit to lessen the load at start up.

Brian

Because they enable you to vary the speed of an induction motor with something
like its normal torque and
no need for changeable belts and suchlike.

--
Roger Hayter