power losses induction machine
I think that formula just says that the torque delivered to the load is equal to the load inertia, J, multiplied by the rotational acceleration, dw/dt plus the torque required to turn the load without acceleration. The 2/P term may be an adjustment for units of measure. If there is no external load, the torque developed by the rotor is equal to the torque required to accelerated the rotor inertia plus the torque losses consisting of friction and aerodynamic drag.