Coasting Down; Torque Control And Pump Stop - Siemens 3RW44 Manual

7.3.1

Coasting down

"Coasting down" means the power supplied to the motor via the soft starter is interrupted
when the ON command is removed from the starter. The motor will coast down freely, driven
only by the mass inertia (centrifugal mass) of the rotor and load. This is also referred to as a
natural run-down. A large centrifugal mass means a longer stop time without load.
Typical applications for coasting down
Costing down is used for loads that place no special demands on the stopping behavior, e.g.
large fans.
7.3.2

Torque control and pump stop

In the case of "torque-controlled stop" and "pump stop", coasting down or the natural run-
down of the load is decelerated. This function is set if there is a need to prevent the load
from being stopped abruptly. Applications involving small mass inertia values or high
counter-torques are typical examples.
For optimum torque control during the stopping procedure, enter the motor data of the motor
connected to the soft starter in the selected parameter set using the "Setting" menu item.
Coast-down time and stopping torque
The "Coast-down time" parameter on the soft starter allows you to specify how long power
should still be supplied to the motor after the ON command is removed. Within this coast-
down time, the torque produced in the motor is continuously and linearly reduced to the set
stopping torque, and the application is smoothly stopped.
3RW44 soft starters
Manual, 03/2017, NEB535219502000/RS-AB/008
Device functions
7.3 Coasting methods
129