MACHINE from reaching the rated torque value is known as Parasitic torque.It is also responsible for the torsional shaft failure of induction motors. Hence, they are undesirable.Asynchronous parasitic torques occur when a harmonic 'ν' of the stator MMF (or its airgap flux density) PRODUCES in the rotor cage currents whose MMF harmonic has the same order 'ν'. Where v is the stator MMF harmonics orders like ν =−5,+7,−11,+13,−17,+19, … Pull up torque:The Pull-up Torque is the minimum torque developed by an electric motor when it runs from zero to full-load speed (before it reaches the break-down torque point).When a motor starts and begins to accelerate the torque, in general, will DECREASE until it reaches a low point at a certain speed - the pull-up torque - before the torque increases until it reaches the highest torque at a higher speed - the break-down torque - point.The pull-up torque may be critical for applications that need the power to GO through some temporary barriers to achieving working conditions. Locked Rotor or Starting Torque:The Locked Rotor Torque or Starting Torque is the torque an electrical motor develops when starting at zero speed.A high Starting Torque is more important for application or machines hard to start - like positive displacement pumps, CRANES etc. A lower Starting Torque can be accepted for centrifugal fans or pumps where the start load is low or close to zero. Break-down Torque:The Break-down Torque is the highest torque available before the torque decreases when the machine continues to accelerate to working conditions. Full-load (Rated) Torque or Braking Torque:The Full-load Torque is the torque required to produce the rated power of an electrical motor at full-load speed.