Calculating The Energy Saving For Fluid Flow Machines - Siemens SINAMICS G115D Operating Instructions Manual

Advanced commissioning

6.26 Calculating the energy saving for fluid flow machines

6.26 Calculating the energy saving for fluid flow machines
Overview
Fluid flow machines, which mechanically control the flow rate using valves or throttle flaps,
operate with a constant speed corresponding to the line frequency.
The lower the flow rate, the poorer the efficiency of the fluid flow machine (pump). The fluid
flow machine (pump) has the poorest efficiency when the throttle or valve is completely
closed. Further, undesirable effects can occur, for example the formation of vapor bubbles in
liquids (cavitation) or the temperature of the medium being pumped can increase.
The converter controls the flow rate by appropriately varying the speed of the fluid flow
machine. By controlling the flow rate, the fluid flow machine operates at the optimum
efficiency for each flow rate. This situation means that in the partial load range less electric
power is required than when controlling the flow rate using valves and throttles.
Function description
276
The converter calculates the en-
ergy saving from the flow charac-
teristic associated with a
mechanical flow control and the
measured electric power that is
drawn.
The calculation is suitable for
centrifugal pumps, fans, radial
and axial compressors, for in-
stance.
Operating Instructions, 09/2020, FW V4.7 SP13, A5E48681219B
SINAMICS G115D distributed drive