Functions
7.4 Motor protection
SIRIUS 3RW50 soft starter
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Manual, 09/2019, A5E35628455002A/RS-AA/001
7.4
Motor protection
The 3RW50 soft starter has two functions for protecting the motor:
●
Electronic motor overload protection
●
Thermistor motor protection with temperature sensor (optional)
Use a combination of both of these functions to implement full motor protection.
7.4.1
Electronic motor overload protection
Operating principle
The approximate temperature of the motor is calculated using the measured motor currents
and the parameter settings "Rated operational current I
e
" and "tripping class". This indicates
whether the motor is overloaded or is functioning in the normal operating range. When
overload is detected, the 3RW50 soft starter shuts the motor down. The setting for
RESET MODE determines how the motor is restarted.
Parameter
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.
NOTICE
Damage to property possible due to deactivated motor protection.
If the motor is not monitored by a temperature sensor and the tripping class is set to
"CLASS OFF", no motor protection is provided.
