Skip Speeds And Minimum Speeds - Siemens SINAMICS S150 Operating Instructions Manual

Setpoint channel and closed-loop control
7.2 Setpoint channel
7.2.3

Skip speeds and minimum speeds

Description
Variable-speed drives can generate critical whirling speeds within the control range of the
entire drive train. This prevents steady-state operation in their proximity; in other words,
although the drive can pass through this range, it must not remain within it because resonant
oscillations may be excited. The skip frequency bands allow this range to be blocked for
steady-state operation. Because the points at which critical whirling speeds occur in a drive
train can vary depending on age or thermal factors, a broader control range must be
blocked. To ensure that the speed does not constantly increase and decrease in the
suppression bandwidth (speeds), the bands are assigned a hysteresis.
Specifying a minimum speed allows a specific range to be disabled around speed rpm for
steady-state operation.
Signal flow diagram
Figure 7-1
Function diagram
FP 3050
262
Signal flow diagram: Skip frequency speeds and minimum speeds
Skip frequency bands and speed limiting
Drive converter cabinet units
Operating Instructions, 07/07, A5E00288214A