Temperature Monitoring; Asymmetry Monitoring - Siemens 3RK1308‑0 00‑0CP0 Series Equipment Manual

Functions
6.7 Substation monitoring
6.7.6

Temperature monitoring

The motor starter has an internal temperature monitoring function. If the motor starter
exceeds its internal temperature warning threshold, the "Switching element hot" alarm is
issued in data set 75 (Page 184). The motor starter switches off if the temperature continues
to rise. The "Switching element overload" diagnostic message (object number 309) is issued
in data set 92 (Page 186) if temperature monitoring responds.
You can trigger trip reset on the motor starter after a cooling time of at least three minutes.
You can activate the motor starter again once it has sufficiently cooled down.
Fan control
The fan is controlled temperature-based by the internal temperature monitoring function. The
thermal device protection model can also lead to the activation of the fan.
6.7.7

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 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
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Motor starter (3RK1308‑0**00‑0CP0)
Equipment Manual, 11/2019, A5E34821005002A/RS-AC/003