Limiting start output torque...help please

[crysta0728]

I want to show the parameters for limiting the start output torque of a 300amp stater/generator to that of a 200amp starter generator but be able to keep the generator to run at 300amp. Does anyone know what the correct equation would be to show the decreasing of torque at startup? And how can I describe torque besides as a funtion of force and distance? help please, Im lost in a mess of formulas.

 

[aolalde]

For DC motors the torque developed is proportional to the field (If) and armature (Ia) currents. T = k If*Ia
Assuming series motors the field and armature current are the same and the torque developed will be: T = k*Ia^2
The constant “k” (electromechanical conversion constant) is a function of the windings and magnetic circuit (iron) and needs to be defined for each motor construction.
Torque (T) is the product of each armature conductor force (Lb) times the average radius times the number of conductors.
T is given in (Lb*Ft) if the total force is given in Lb and the armature conductor radius is in Ft.
For metric units (MKS) the basic principles are the same.
A simple way to limit the torque is made by connecting an adjustable series resistor, set to reduce the excess of current and when desired it is short-circuited to allow 100% current to the starter. Note that the current in such a resistor is high (200 to 300 amps)