RE: [CAD_CAM_EDM_DRO] Re: spindles powered by REGULAR AC induction motor

>-----Original Message-----
>From: Jeff DelPapa [mailto:dp@...]
> aircraft gyroscope that blew up! I'm guessing he fired up a 12 V
> gyro on 28 V by mistake, and it overspeeded! Now, this thing has
> a rotor weighing about a pound, and it was presumably only going
> twice its rated speed!
>Likely 4x the speed. Remember "Twinkle Twinkle little star, power
>equals V *SQUARED* over R". 2x voltage, 4x power. (dc motors and
>resistors anyway).

Likely only 2x speed. In a PM DC motor, speed is proportional to voltage. In a
shunt-field motor, field flux is proportional to the voltage, so if you double
the supply voltage, the flux is doubled, and at any particular speed the back
voltage is also doubled, so the speed will be pretty much unchanged.
Series-field and compound-field motors are trickier to analyze...

Another way of looking at it is 2x speed gives 4x energy, and 4x or 8x
frictional drag, and thus 4x power consumption, which, as you mention, is 2x
voltage.
-Kevin Martin