Asymmetry Monitoring - Siemens SIMATIC ET 200SP Manual

3.7.7.7

Asymmetry monitoring

Description
Three-phase asynchronous motors respond to slight asymmetries in the supply voltage with
a higher asymmetric current consumption. As a result, the temperature in the stator and rotor
windings of the drive increases. The SIMATIC ET 200SP motor starter protects the load
against overload by issuing a warning or by tripping. You can parameterize whether a
warning is output or tripping occurs.
Note
When the motor is switched on, asymmetry evaluation is suppressed for approx. 0.5 s.
Asymmetry limit
The asymmetry limit is a percentage value by which the motor current is allowed to deviate
in each phase. Asymmetry is detected as soon as one of the three phases deviates by more
than 40 % from the mean value of all phases.
Response to asymmetry
You use this device parameter to determine the behavior of the motor starter in the event of
asymmetry:
● Warning (not permissible for fail-safe motor starters in ATEX operation)
● Tripping
Settings
Table 3- 3
Device parameters
Response to asymmetry
See also
Overload protection (Page 42)
Motor starter (3RK1308-0**00-0CP0)
Manual, 12/2016, A5E34821005002A/RS-AB/002
Settings for asymmetry monitoring
Default setting
Tripping
Product overview
3.7 Functions
Setting range
Warn
•
Tripping
•
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