As of the 8000-4 Catalog, released in 2002, Compumotor changed the way that we rate stepper motor currents. The old model was to determine the current that will run the motor, at its peak power point and 100% duty cycle, as close to 100�C case temperature without going over and not saturating the winding more than 15%.
The new model that was used in all newer speed/torque curves in the 8000-4 Catalog is as follows:
Determine the current that will run the motor, at its peak power point or 20 rps (which ever is lower) and 75% duty cycle, as close to 100�C case temperature without going over and not saturating the winding more than 15%. A 10" x 10" x 0.25" aluminium heatsink was used for all these measurements.
The link below shows all of the current motors and drives with the new current ratings. Note: Most older manuals will not be updated with this information, like the Zeta, Gemini, and OEM750 manuals.
New Stepper Currents
This change is mostly due to normalizing our ratings with the market, but some applications still require 100% duty cycle or running the motor above 20 rps, which could be where the peak power point is, depending on the motor. The link below shows all of the current motors and drives with the old current ratings.
Note: There is no old model data on the VS series of motors.
Old Stepper Currents
All motor/drive currents are selected with the motor connected to a 10" X 10" X 0.25" aluminum heatsink. If the application has no heat sink for the motor then the current and torque will need to be derated.
