Soft Starting With Torque Control And Current Limiting - Siemens SIRIUS 3RW55 Manual

7.2.6

Soft starting with torque control and current limiting

Operating principle
Select the startup function torque control + current limiting if, at the same time as protecting
the system during startup of the motor or the connected load, you want to ensure that a
specific current value is not exceeded.
The motor is always started up with the torque control. If the current exceeds the
parameterized current limit, the torque ramp is aborted and the current limiting function
starts. If the motor current drops below the limit value again, depending on the advanced
stage of run-up, then the torque ramp function takes over control again until the motor has
finished running up.
Application
● Avoiding current surges
● Reducing energy costs
● During heavy starting
Diagram
①
②
③
SIRIUS 3RW55 soft starter
Manual, 08/2018, A5E35630887002A/RS-AB/002
I
direct motor starting
I : Adjustable current limiting value
soft starter
Torque control
Functions
7.2 Start-up
91