On 14/08/16 16:54, Fredxxx wrote:
On 14/08/2016 13:54, The Natural Philosopher wrote:
On 14/08/16 13:32, Tim Streater wrote:
In article , Tim Lamb
wrote:

In message ,
harry writes
On Saturday, 13 August 2016 20:22:17 UTC+1, Tim Lamb wrote:
These are expensive and wear out so these days it's replaced with
electronics to turn DC to AC where ever possible.

Hmm.. suppose the commutator is simply switching the current to a
different winding on the armature? Direction of flow may not change
which appears to me to be DC.

The current direction reverses as the commutator segnebt passes under
the brush.

You mean the armature is wound such that the magnetic flux generated
by the winding is reversed?

What's all this about brushes that harry is rabbitting on about. Didn't
think motors had those these days (unlike the cheapies that ran toy
electric trains when I was a nipper).

Some do, some don't.

If they are DC motors and they dont have brushes, they have electronics
doing the same job.

I agree with you, and there is a consensus here that they are still
called DC motors.

What something is called and what it is, are often wildly different.

I've heard comrade Corbyn referred to as intelligent and compassionate.


--
"Anyone who believes that the laws of physics are mere social
conventions is invited to try transgressing those conventions from the
windows of my apartment. (I live on the twenty-first floor.) "

Alan Sokal