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January 23rd Component of load torques(Tl)
•Friction Torque (TF): Friction will be present at the motor shaft and also in various parts of the load. •The friction torque (TF) is the equivalent value of various friction torques referred to the rotor shaft. Friction torque
Windage torque •Windage Torque (Tw): When a motor runs, the wind generates a torque opposing the motion. This is known as the windage torque. Tw= Cwm2 where C is a constant.
Torque required to do the useful mechanical work(TL) •Nature of this torque depends on particular application. •It may be constant and independent of speed, Some function of speed, it may be time invariant or time variant. •The nature of the torque may change with the change in the loads mode of operation.
Stiction •Its value at standstill is much higher than its value slightly above zero speed. •Friction at zero speed is called stiction. •Drive to start , motor torque should at least exceed stiction.