Motor Protection / Intrinsic Device Protection (3Rw40 Only); Motor Protection Function - Siemens SIRIUS 3RW30 Manual

Functions

5.3 Motor protection / intrinsic device protection (3RW40 only)

5.3 Motor protection / intrinsic device protection (3RW40 only)
Note
If the soft starter is disconnected because the motor overload protection or the intrinsic
device protection trips, you must wait a defined cooling time (recovery time) prior to
acknowledging the fault or starting the motor again. (Motor overload tripping time: 5 minutes,
temperature sensor: after cooling,
intrinsic device protection tripping time:
- 30 seconds upon overload of the thyristors,
- 60 seconds upon overload of the bypasses)
5.3.1

Motor protection function

The motor overload protection function is implemented on the basis of the winding
temperature. This indicates whether the motor is overloaded or functioning in the normal
operating range.
The winding temperature can either be calculated with the help of the integrated, electronic
motor overload function or measured with a connected motor thermistor.
The two types of protection must be combined to achieve full motor protection. This
combination is recommended to protect the motor optimally.
Note
Thermistor motor protection evaluation
The thermistor motor protection evaluation function is optionally available for the SIRIUS
3RW402 to 3RW404 soft starters in the 24 V AC/DC control voltage version.
Motor overload protection
The current flow during motor operation is measured by measuring the current with
transformers integrated in the soft starter. The temperature rise in the winding is calculated
based on the rated operational current set for the motor.
A trip is generated by the soft starter when the characteristic is reached, depending on the
trip class (CLASS setting).
ATEX
"Increased safety" type of protection EEx e acc. to ATEX Directive 94/9/EC
The SIRIUS 3RW40 soft starter sizes S0 to S12 are suitable for starting explosion-proof
motors with the "increased safety" type of protection EEx e (type of protection / marking: Ex
II (2) GD).
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SIRIUS 3RW30 / 3RW40
Manual, 10/2018, NEB535199502000/RS-AB/005