Ramp-Function Generator - Siemens SINAMICS G120D Operating Instructions Manual

Advanced commissioning
6.4 Setpoint calculation
6.4.6

Ramp-function generator

The ramp-function generator in the setpoint channel limits the rate of change of the speed
setpoint (acceleration). Reduced acceleration lowers the accelerating torque of the motor. In
this case, the motor reduces the load on the mechanical system of the driven machine.
You can select between two different ramp-function generator types:
● Extended ramp-function generator
The expanded ramp-function generator limits not only the acceleration but also the
change in acceleration (jerk) by rounding the setpoint. In this case, the torque does not
rise suddenly in the motor.
● Basic ramp-function generator
The basic ramp-function generator limits the acceleration, however not the rate the
acceleration changes (jerk).
If you use a 1FK7 encoderless synchronous motor, we recommend using an extended ramp-
function generator with an initial rounding of at least 0.1 s.
Extended ramp-function generator
The ramp-up and ramp-down times of the extended ramp-function generator can be set
independently of each other. The optimum times that you select depend on your particular
application in question and can range from just a few 100 ms (e.g. for belt conveyor drives)
to several minutes (e.g. for centrifuges).
Initial and final rounding permit smooth, jerk-free acceleration and braking.
The ramp-up and ramp-down times of the motor are increased by the rounding times:
● Effective ramp-up time = p1120 + 0.5 × (p1130 + p1131).
● Effective ramp-down time = p1121 + 0.5 × (p1130 + p1131).
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Operating Instructions, 07/2016, FW V4.7 SP6, A5E34262100B AD
Converter with control units CU240D-2