[GreenKeys] Hughes Printing Telegraph

[Jim Haynes]

On Tue, 19 Jul 2011, Rokumon Cat wrote:
>  
> Someone correct me if I am wrong, but I think that if the motor is a
  series wound motor, that if the load is removed, that it will 'run away'
  and destroy itself if the load is removed while the power is applied.
>  
That's a hazard with large motors.  With small motors it isn't a hazard
because there are always enough losses to keep them from running away.
I'm not sure just how big a motor has to be for that to be a problem.
You can run the ordinary electric drill, or a Dremel tool, or a car 
starter motor with no load without danger.  When I was an E.E. student
50 years ago we had motors maybe 18 inches in diameter in the machinery
lab and it was definitely a hazard with motors that big.