On 30/10/2020 20:23, Roger Hayter wrote:
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.

It is used bt all 'brushless DC motors', be one in yer Dyson cordless.
It replaces a mechanical commutator.

--
€œThose who can make you believe absurdities, can make you commit
atrocities.€�

€• Voltaire, Questions sur les Miracles Ã* M. Claparede, Professeur de
Théologie Ã* Genève, par un Proposant: Ou Extrait de Diverses Lettres de
M. de Voltaire