Motor Protection; Electronic Motor Overload Protection; Motor Protection (Page 166); Electronic Motor Overload Protection (Page 166) - Siemens SIRIUS 3RW55 Equipment Manual

Functions

8.3 Motor protection

8.3 Motor protection
The 3RW55 and 3RW55 Failsafe soft starters have 2 functions for protecting the motor:

• Electronic motor overload protection

• Thermistor motor protection with temperature sensor
Use a combination of both of these functions to implement full motor protection.
NOTICE
Deactivated motor protection can cause material damage.
If the motor is not monitored by a temperature sensor and the trip class is set to "CLASS OFF",
no motor protection is provided.
Reset after cooling time
If the 3RW55 or 3RW55 Failsafe soft starter is switched off via a motor protection or intrinsic
device protection tripping operation, the action cannot be acknowledged using the "Reset"
function until the displayed cooling time has expired.
The behavior of the soft starter after an acknowledgment depends on the "Response to
overload ..." parameter set for the particular function.
8.3.1 Electronic motor overload protection
Operating principle
The electronic motor overload protection calculates the approximate temperature of the motor
from the measured motor currents and the device parameters "Rated operational current I
"Trip class". This indicates whether the motor is overloaded or is functioning in the normal
operating range. To do this, set the motor parameters (Page 95) of your motor.
The current motor temperature rise can be displayed via the measured value "Motor
temperature rise" (Page 227)
166
SIRIUS 3RW55 and 3RW55 Failsafe Soft Starters
Equipment Manual, 02/2022, A5E35630887002A/RS-AF/006
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