Siemens SIMATIC ET 200pro Quick Manual page 158

10.5 Asymmetry
Description
Three-phase induction motors respond to slight asymmetries in the mains volt-
age with a higher asymmetric current consumption. As a result, the tempera-
ture in the stator and rotor winding increases.
Caution
When the motor is switched on, the asymmetry evaluation is suppressed for
approximately 500 milliseconds.
10.5.1 Device parameters for asymmetry – descriptions
Asymmetry limit value (can only be parameterized for high feature motor starters)
The 'asymmetry limit value' is a percentage value by which the motor current is
allowed to vary in the individual phases.
Asymmetry occurs when the difference between the smallest and largest
phase current is greater than the parameterized asymmetry limit.
The reference value for the evaluation is the maximum phase current in one of
the three phases!
Setting range: 30% to 60% of the rated operating current
Response to asymmetry
(can be parameterized for standard and high feature motor starters)
This device parameter configures how the motor starter responds to asymme-
try:
• Warning
• Tripping
10-18
SIMATIC - ET 200pro motor starter
GWA 4NEB 950 5661-02 DS 04