On 25/11/2012 3:02 AM, Lord Androcles, Zeroth Earl of Medway wrote:> such that the peak torque is near standstill. > > ====================================================== > Triacs should only be used when the load is resistive. > At standstill (say you lock the shaft of a squirrel cage induction motor) > one can view the stator as the primary of a transformer and the rotor > as the secondary with a shorted turn. That is max torque. As the rotor > accelerates the difference between the rotor RPM and field RPM of the > stator (known as the slip frequency) gradually reduces to zero at > synchronous speed and the torque vanishes, the motor is then just > an inductive load like a transformer with no load on the secondary. > I can't imagine why anyone would want a variable speed fan in a > stove hood.
I have responded under Re: motor control as this is the direction that the discussion has gone. -- Don Kelly cross out to reply