Figure 10-5: Principle Of Soft Start-Up / Soft Run-Down - Siemens SIMATIC ET 200pro Quick Manual

10.8 Soft starter control function
Description
Soft starters work according to the principle of phase angle control.
You can specify soft start-up and soft run-down with a variable voltage ramp.
The following diagram shows the principle:
U
Mains
voltage
Start
voltage

Figure 10-5: Principle of soft start-up / soft run-down

Disabling the soft starter control function
Parameterizing the start-up and run-down time to zero does not lead to direct
switch-on of the motor. The switch-on current is still limited to the parameter-
ized value, which ensures a jolt-free start-up of the motor!
If the motor is to be switched on directly, the start-up type "direct" must be
selected.
Caution
With the soft starter control function disabled, you must observe the following
derating:
Reduction of the rated operating current from 12 A to 9 A up to Class 10.
10-26
Soft start-up
t
Start-up time
U
Soft run-down
Mains
voltage
Stop
voltage
Run-down time
SIMATIC - ET 200pro motor starter
GWA 4NEB 950 5661-02 DS 04
t