Setting functions
8.4 Setpoint calculation
Converter with control units CU250D-2
Operating Instructions, 04/2014, FW V4.7, A5E34261542B AA
131
The ramp-function generator in the setpoint channel limits the rate that the speed setpoint
changes. As a consequence the motor accelerates and brakes more softly, reducing the
stress on the mechanical system of the driven machine.
You can select between two different ramp-function generator types:
● Extended ramp-function generator
The extended ramp-function generator limits acceleration and jerk. The motor accelerates
especially gently. The extended ramp-function generator can also solve problems in
machines with high breakaway torques.
● Basic ramp-function generator
The basic ramp-function generator limits the acceleration, however not the rate the
acceleration changes (jerk).
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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