Years ago I had success putting a capacitor across an induction motor 
winding to stop it. Used a motor starting capacitor (rated for AC), 
something like 100 microfarad as I remember. There was enough residual 
magnetism that it worked without any other excitation.

If you try this, check the voltage across the capacitor while stopping 
to be sure the capacitor is rated for it. The voltage could be much 
higher than when the motor is running.

Karl


On 06/01/2011 11:45 AM, Peter Blodow wrote:
> Gene, I suppose that your "AC universal motor" is an induction motor
> with a field winding and a cage rotor. (If it were a motor with rotor
> windings and a brush armature, it would be a AC-DC-universal motor and
> the following recipe would not apply). When the power supply is cut off,
> there is no magnetic field any more to exert a braking momentum.
> Therefore with that sort of a motor you need an additional  field
> supply, say 24 V DC or even better 117 V one phase rectified. After
> power off, this voltage must be applied for a few seconds (time relay),
> and it will bring the rotor to a stop very quickly. Machines without
> this feature are not allowed to be sold or applied in Germany.
>
> The only other way would be a mechanical spring loaded brake right on
> the saw shaft, held open by the supply voltage as long as the motor is
> running.

------------------------------------------------------------------------------
Simplify data backup and recovery for your virtual environment with vRanger. 
Installation's a snap, and flexible recovery options mean your data is safe,
secure and there when you need it. Data protection magic?
Nope - It's vRanger. Get your free trial download today. 
http://p.sf.net/sfu/quest-sfdev2dev
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Reply via email to