Rockwell Automation Publication 2198-UM002G-EN-P - February 2019 415
Motor Control Feature Support Appendix E
Skip Speeds
Some machines have a resonant operating frequency (vibration speed) that is
undesirable or could cause equipment damage. To guard against continuous
operation at one or more resonant points, you can configure the skip-speed
attributes in the Logix Designer application>Axis Properties>Parameter List
category.
The value that is programmed into the SkipSpeed1 or SkipSpeed2 attribute
sets the central speed of a skip-speed band within which the drive does not
operate. The width of the band is determined by the SkipSpeedBand attribute.
The range is split, half above and half below the SkipSpeedx attribute. Any
command set-point within this band is adjusted by the skip-speed feature to
fall at either the upper or lower skip-speed band boundary value. The skip-
speed feature contains hysteresis (25% of the SkipSpeedBand value) to prevent
frequent switching of VelocityReference.
Figure 218 - Single Skip Speed Example
A SkipSpeedBand value of 0 disables the skip-speed feature.
Time
SkipSpeedBand Upper Boundary
SkipSpeedBand Lower Boundary
SkipSpeed
Speed
Velocity
Setpoint
Velocity
Reference
IMPORTANT When a single SkipSpeed value is desired, the SkipSpeed1 and
SkipSpeed2 settings must be the same.
IMPORTANT Acceleration and deceleration are affected by the skip-speed feature. Too
large of a SkipSpeedBand value can result in an overcurrent drive fault.
IMPORTANT The MaximumFrequency attribute is always enforced. Skip-speed band
boundary values beyond the MaximumFrequency value do not apply.
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