Ramp-Function Generator - Siemens SINAMICS G120 Operating Instructions Manual

7.5.2

Ramp-function generator

The ramp-function generator in the setpoint channel limits the speed of changes to the
speed setpoint. The ramp-function generator does the following:
● The soft acceleration and braking of the motor reduces the stress on the mechanical
● Acceleration and braking distance of the driven machine (e.g. a conveyor belt) are
Ramp-up/down time
The ramp-up and ramp-down times of the ramp-
function generator can be set independently of each
other. The times that you select depend purely on
the 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).
When the motor is switched on/off via ON/OFF1,
the motor also accelerates/decelerates in
accordance with the times set in the ramp-function
generator.
Ramp-up time (p1120)
Duration of acceleration (in seconds) from zero speed to the maximum speed P1082
Ramp-down time (P1121)
Duration of deceleration (in seconds) from the maximum speed P1082 to standstill
The quick-stop function (OFF3) has a separate ramp-down time, which is set with P1135.
Note
If the ramp-up/down times are too short, the motor accelerates/decelerates with the
maximum possible torque and the set times will be exceeded.
For more information about this function, see the List Manual (function diagram 3060 and the
parameter list).
Extended ramp-function generator
In the extended ramp-function generator, the acceleration process can be made "softer"
using initial and final rounding via parameters p1130 ... p1134. Here, the ramp-up and ramp-
down times of the motor are increased by the rounding times.
Rounding does not affect the ramp-down time in the event of a quick stop (OFF3).
For more information, see the List Manual (the parameter list and function diagram 3070).
Inverter with CU240B-2 and CU240E-2 Control Units
Operating Instructions, 01/2011, FW 4.4, A5E02299792B AB
system of the driven machine.
independent of the motor load.
Functions
7.5 Setpoint calculation
167