Functions
7.4 Motor protection
SIRIUS 3RW50 soft starter
128
Manual, 09/2019, A5E35628455002A/RS-AA/001
7.4.2
Thermistor motor protection with temperature sensor (optional)
Operating principle
WARNING
Automatic restart following fault acknowledgement/restart.
Can cause death or serious injury.
The 3RW50 soft starter immediately continues to operate with the values specified by the
control following fault acknowledgement/restart. Outputs are activated when the ON
condition is met.
Take appropriate measures (e.g. start key with monitored start) to prevent unintentional
restarting and to ensure a defined start of the system.
You can connect the temperature sensor of the motor to the 3RW50 soft starter and evaluate
it. If a specific motor-dependent temperature is exceeded, the 3RW50 soft starter recognizes
this and reacts accordingly.
Two different types of measuring sensor can be connected to the 3RW50 soft starter:
●
PTC thermistors type A
●
This sensor type is a temperature-dependent resistor.
Thermoclick
This sensor type is a temperature-dependent switch.
Note
ATEX / IECEx-certified motor overload protection
Note that the sensor type "Thermoclick" is not permissible when operating motors in
hazardous areas.
If the thermistor motor protection is tripped, the 3RW50 soft starter cannot be restarted until
the sensor installed in the motor has cooled down. The recovery time varies according to the
temperature state of the sensor.
The sensor cables of PTC thermistors type A can be monitored for wire break and
short-circuit.
Further information
You will find further information on resetting the faults in Chapter RESET MODE (Page 98).
You will find more information on the connection of the temperature sensor in Chapter
