A shunt motor can act very much like an AC induction motor in this
regard. This is a reason they are popular for escalators, conveyor
belts, and elevators -- you give them more load and they hardly slow
down. Sometimes they are called "constant speed" motors. Putting more
voltage on a shunt motor doesn't speed it up, but makes it "stiffer"
against slowing down under load.

Also, an AC induction motor does slip, and until breakdown more slip
= more torque (like a shunt motor!).

--- Victor Tikhonov <[EMAIL PROTECTED]> wrote:
> Also increasing [AC] voltage will not 
> make AC motor run faster. *You* need to take care of frequency
> increase to achieve that. This is different from DC motors where
> the frequency converter (commutator) is part of the rotor and you
> have no control over that (cannot control frequency and voltage
> separately as you can for AC motors.
> 
> High voltage and low frequency makes the motor "stiff", spinning
> with some RPM regardless of the load (almost like stepper motor),
> while lower voltage will make it "softer". You cannot do that with
> DC motor - higher load will inevitably lower its RPM.
> (closed loop controls aside here).
 
 


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