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

Functions

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

Water hammer can be reduced compared to direct or wye-delta starting by using the SIRIUS
3RW40 soft starter. An optimum pump stop is achieved using a SIRIUS 3RW44 soft starter
with an integrated pump stop function (refer to chapter Comparison of device functions [Page
24]).
Typical applications for soft stop
Use soft stop for
• Pumps to reduce water hammer.
• Conveyor belts to prevent the conveyed product from tilting.
5.3 Motor protection / intrinsic device protection (3RW40 only)
NOTICE
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: 60
seconds, temperature sensor: after cooling, intrinsic device protection tripping time: >
30 seconds)
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.
32
SIRIUS 3RW30 / 3RW40
Manual, 01/2010, 535 1995-02 DS01