Torque Control And Pump Stop - Siemens Sirius 3RW44 System Manual

Device functions

6.3.2 Torque control and pump stop

Stopping time and
stopping torque
Pump stop
Typical applications for soft stop / pump stop
6-12
In torque-controlled and pump stop mode, the coasting down process/natural
run-down of the load is extended. This function is set if abrupt stopping of the
load is to be prevented. This is typical in applications with small mass
reactances or high counter torques.
For optimum torque control during the stopping process, the motor data of the
motor connected to the soft starter should be entered in the selected
parameter. This can be specified using the Setting menu item.
The stopping time parameter of the soft starter, can be used to specify for how
long power should be fed into the motor after removal of the switch-on
command. Within this stopping time, the torque generated in the motor is
continuously and linearly reduced to the set stopping torque and the application
is smoothly stopped.
In pump applications, so-called water hammers may occur if the drive is stopped
abruptly without using pump stop. This water hammer is caused by the sudden
stall and the accompanying pressure variations in the pump. It involves noise
and mechanical impact on the piping and on flaps and valves inside the system.
Motor torque
M
M
Nominal operation
Stopping torque
Fig. 6-7: Soft stop / pump stop
In pumps to prevent water hammer.
In conveyor belts to prevent goods from toppling.
Stopping time
Stop command
at
soft starter
Time
s
SIRIUS 3RW44 manual
GWA 4NEB 535 2195-02 DS 01