Siemens SINAMICS G120C User Manual

8.33 Calculating the energy saving for 󹪞uid 󹪞ow machines
Overview
Fluid 󹪞ow machines, which mechanically control the 󹪞ow rate using valves or throttle 󹪞aps,
operate with a constant speed corresponding to the line frequency.
/LQHVXSSO\
3XPS
/LQHVXSSO\
+]
+]
Figure8-82 Flow control with pump and throttle connected to a 50 Hz line supply
The lower the 󹪞ow rate, the poorer the e󹪟ciency of the 󹪞uid 󹪞ow machine (pump). The
󹪞uid 󹪞ow machine (pump) has the poorest e󹪟ciency when the throttle or valve is completely
closed. Further, undesirable e󹪜ects 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 󹪞ow rate by appropriately varying the speed of the 󹪞uid 󹪞ow
machine. By controlling the 󹪞ow rate, the 󹪞uid 󹪞ow machine operates at the optimum
e󹪟ciency for each 󹪞ow rate. This situation means that in the partial load range less electric
power is required than when controlling the 󹪞ow rate using valves and throttles.
/LQHVXSSO\
,QYHUWHU
/LQHVXSSO\
,QYHUWHU
+]
+]
Figure8-83 Flow control with pump and converter
Function description
)ORZUDWHFRQWUROXVLQJ
DWKURWWOHIODS
5HTXLUHG
HOHFWULF
SRZHU
)ORZUDWH
(QHUJ\VDYLQJ
&RQWUROOLQJWKHIORZUDWH
XVLQJDQLQYHUWHU
The converter calculates the en‐
ergy saving from the 󹪞ow charac‐
teristic associated with a mechan‐
ical 󹪞ow control and the meas‐
ured electric power that is drawn.
The calculation is suitable for cen‐
trifugal pumps, fans, radial and
axial compressors, for instance.
$
%
&
Advanced commissioning
8.33Calculating the energy saving for 󹪞uid 󹪞ow machines
SINAMICS G120C Converters
Operating Instructions, 02/2023, FW V4.7 SP14, A5E34263257B AK 357

Siemens SINAMICS G120C Specifications

General

Brand	Siemens
Model	SINAMICS G120C
Category	Inverter
Language	English