Siemens CU240B-2 - Protecting the Motor by Calculating the Motor Temperature

Advanced commissioning
6.6 Protection functions
Converter with the CU240B-2 and CU240E-2 Control Units
Operating Instructions, 01/2016, FW V4.7 SP6, A5E34259001B AC
269
6.6.3
Protecting the motor by calculating the motor temperature
The inverter calculates the motor temperature based on a thermal motor model with the
following properties:
● The inverter calculates the motor temperature:
– In thermal motor model 1, the inverter calculates the temperature in the stator winding.
– In thermal motor models 2 and 3, the inverter calculates the temperatures in the rotor
and in the stator winding.
● The thermal motor model detects temperature increases much faster than a temperature
sensor.
● After switching off the supply voltage, the inverter saves the most-recently calculated
difference to the ambient air temperature (factory setting: p0610 = 12). After switching the
supply voltage on again, the thermal motor model starts with 90% of the previously saved
difference temperature.
If you use the thermal motor model together with a temperature sensor, e.g. a PT1000, the
inverter corrects the model using the measured temperature.