Pump Stop - Siemens SIRIUS 3RW55 Manual

Functions
7.3 Run-down
7.3.4

Pump stop

Operating principle
In the case of a torque-controlled pump stop, the stopping of the load is extended. This
function is set if there is a need to prevent the load from being stopped abruptly. This is
typical in applications with a low mass inertia or a high counter-torque. In order to use the
"alternative stopping" function, activate the "alternative stopping mode" control function via
one of the following control sources:
● Input action
● 3RW5 communication module (PIQ)
● 3RW5 HMI High Feature
You will find additional information on input actions in Chapter Control (Page 162).
Due to the very low moment of inertia in pumps, the pump operating mechanism (motor) can
come to a standstill suddenly when shutting down, due to the counter-pressure of fluid in the
piping system. This can result in pressure fluctuations in the pipe system which in turn cause
loud noises (water hammer) and mechanical problems, e.g. to return valves. For this reason,
the flow rate of the pump is reduced gradually during pump stop. In the case of smaller
pumps this effect can often be ignored.
Application
● Drives for which the abrupt stopping of the load is to be prevented.
● Applications with a low mass inertia or a high counter-torque.
Diagram
①
②
100
Voltage ramp stopping mode
Pump stop stopping mode
SIRIUS 3RW55 soft starter
Manual, 08/2018, A5E35630887002A/RS-AB/002