Calculating The Energy Saving For Fluid Flow Machines - Siemens Sinamics G110M 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
Fluid flow machines, which mechnically control the flow rate using valves or throttle flaps,
operate with a constant speed corresponding to the line frequency.
Figure 6-68
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 inverter controls the flow rate by appropriately varying the speed of the fluid flow
machine. As a consequence, the fluid flow machine has the optimum efficiency for each flow
rate, and draws less electric power in the partial load range than for closed-loop control
concepts based on valves and throttle flaps.
Figure 6-69
Function
278
Flow control with pump and throttle connected to a 50 Hz line supply
Flow control with pump and inverter
The inverter calculates the ener-
gy 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.
Distributed converter for SIMOGEAR geared motors
Operating Instructions, 09/2017, FW V4.7.9, A5E31298649B AH