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
set. 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. These water hammers are caused by the
sudden break in the flow and the accompanying pressure deviations in the
pump. They cause noise
and a mechanical impact on the piping as well as on the flaps and valves inside
the system.
Motor
torque
M
M
Nominal operation
Stopping torque
Figure 6-7:Soft stop / pump stop
Use soft stop / pump stop
• in pumps to prevent water hammers.
• in conveyor belts to prevent goods from toppling.
Caution
Risk of damage to property.
For optimum motor protection use a combination of electronic motor overload
protection and evaluation of a temperature sensor integrated in the motor.
Stopping time
Stop command
at soft starter
Time (t)
s
SIRIUS 3RW44 System Manual
GWA 4NEB 535 2195-02 DS 04