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

Functions
8.1 Start-up
8.1.6

Soft starting with torque control and current limiting

Operating principle
Select the starting mode "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
limitation function starts. The current limitation function remains active until the 3RW55 or
3RW55 Failsafe soft starter detects that the motor has ramped up and the motor is in a normal
operating state.
Application
• Avoiding current surges
• Reducing energy costs
• During heavy starting
Setting via 3RW5 HMI High Feature
• Menu: "Parameters > Soft Starter > Parameter set 1 / 2 / 3 > Start settings > Starting mode >
Torque control + Current limiting"
• Menu (Parameters): "Parameters > Soft Starter > Parameter set 1 / 2 / 3 > Start settings"
• Access protection to the 3RW5 HMI High Feature is not active or has been reset.
Current characteristic
①
②
③
I
e
142
Current characteristic with direct-on-line starting without 3RW55 or 3RW55 Failsafe soft starter
Adjustable current limiting value
Torque control
Rated operational current during rated operation
SIRIUS 3RW55 and 3RW55 Failsafe Soft Starters
Equipment Manual, 02/2022, A5E35630887002A/RS-AF/006