
D-64
Programming
890CS Common Bus Supply - Frames B & D; 890CD Common Bus Drive and 890SD Standalone Drive - Frames E & F
Functional Description
To Set-up Friction at 0 RPM
Run the drive at a very low speed. Observe the SPEED PI OUTPUT diagnostic and set the FRICTION @ 0 RPM parameter to
this value. Return to the SPEED PI OUTPUT diagnostic and verify that it is now zero, or that the noise on the diagnostic is
equally positive and negative.
To Set-up Friction at Nameplate RPM
Run the drive at nameplate rpm Observe the SPEED PI OUTPUT diagnostic and set the FR’N @ NMPLT RPM parameter to
this value. Return to the SPEED PI OUTPUT diagnostic and verify that it is now zero, or that the noise on the diagnostic is
equally positive and negative.
After friction compensation has been set up, the RELATIVE INERTIA parameter can now be set. Relative Inertia is equal to
torque (per unit) / acceleration (revs/s
2
).
Optionally, if the system inertia is known, calculate a starting value to put into the RELATIVE INERTIA parameter. Then
check the value by accelerating the motor plus load and confirming that the PI diagnostic is around zero. Alternatively, find the
Relative Inertia by trial and error: choose a convenient ramp up time, accelerate the motor plus load observing the PI
diagnostic, and find a value of Relative Inertia such that the PI diagnostic is around zero during acceleration and deceleration.