Torque Calculations

Maximum torque? Average torque? Continuous torque?

SHHHHHHHHHHHHHHHHHHHHH! Don't wake up sleeping readers!

The maximum torque is available when the motor is about to accelerate from rest. Use the motor manufacturer's published performance curves to determine this figure.

Here's a typical speed-torque curve from Siemens, notice that the max torque occurs at the pull-out point, about 75% of synchronous speed for this NEMA B motor.

Now everyone can go back to sleep....

Following equation will help you calculate, the torque of the motor:

power (kW) =torque (Nm) x 2 x 3.141 x motor RPM/60,000

You should consider Googling on "motor accelerating torque" where you will find that in addition to the information you provided you will need to know the type of motor (synchronous vs induction), its type of starter/controller (DOL, resistance, delta-wye, etc.) , its nameplate ratings, plus the speed-torque curves for both the motor and the load.

Once you have this information "just" subtract the load torque from the motor torque at every speed of interest and you will have the net accelerating torque required from the motor at each speed. Unfortunately the non-linear nature of both speed-torque curves prevents a simple algebraic equation solution to your question, but writing a computer program or using Mat-Lab is the right way to do this.