Siemens SIRIUS 3RW52 Manual page 95

Parameters
Parameter
Starting voltage
Ramp-up time
SIRIUS 3RW52 Soft Starter
Manual, 01/2019, A5E35630451002A/RS-AD/004
Description
The starting voltage determines the starting torque of the motor. A lower
starting voltage results in a lower switch-on torque and a lower starting
current. Set the starting voltage to a value that ensures that the motor
starts up immediately and smoothly once the start command reaches
the 3RW52 soft starter.
The ramp-up time determines the time taken to increase the motor
voltage from the parameterized starting voltage to the line voltage. This
has an influence on the motor's acceleration torque which drives the
load during the ramp-up operation. A longer ramp-up time results in a
shorter acceleration torque across the motor ramp-up time. The motor
therefore runs up more slowly and smoothly.
Set the length of the ramp-up time such that the motor can reach its
rated speed by the time the end of the ramp is reached. The actual
motor starting time is load-dependent and can differ from the
parameterized ramp-up time.
If you choose a time that is too short, the ramp-up time ends before the
motor has accelerated to speed. If the time selected is too short, a very
high starting current that equals the direct starting current at the same
speed will occur. In this case, the 3RW52 soft starter can switch itself off
via the internal overload protection function and signal a fault.
If parameter value "0" is set, the motor is switched on with a ramp-up
time of approx. 100 ms.
Functions
7.1 Soft starting
95