Liqtec" ("Liqtec Function"); Stop Function" ("Low-Flow Stop Function") - Grundfos LCSE Installation And Operating Instructions Manual

7.16 "LiqTec" ("LiqTec function")

Pump variant
LCSE
VLSE
You can enable the function of the LiqTec sensors in this display.
A LiqTec sensor protects the pump against dry running.
The function requires that a LiqTec sensor has been fitted and
connected to the pump.
When you have enabled the LiqTec function, it stops the pump if
dry running occurs. Restart the pump manually if it has been
stopped due to dry running.
"Dry running detection delay"
You can set a detection delay in order to make sure that the pump
is given a chance to start up before the LiqTec function stops the
pump due to dry running.
Range: 0-254 seconds.
Factory setting
See section
10. Technical data.

7.17 "Stop function" ("Low-flow stop function")

Pump variant
LCSE
VLSE
You can set the "Low-flow stop function" to these values:
"Not active"
•
• "Energy-optimal mode"
• "High-comfort mode"
• "User-defined mode" ("Customised operating mode").
When the low-flow stop function is active, the flow is monitored. If
the flow becomes lower than the set minimum flow (Q
pump changes from continuous operation at constant pressure to
start-stop operation and stops if the flow reaches zero.
The advantages of enabling the "Low-flow stop function" are the
following:
"LiqTec" •
("LiqTec function")
•
•
●
The disadvantages of enabling the "Low-flow stop function" may
●
be the following:
•
•
The impact of the above disadvantages very much depends on
the setting selected for the stop function.
The "High-comfort mode" setting minimizes pressure fluctuations
and acoustic noise.
Select "Energy-optimal mode" if the main priority is to reduce the
energy consumption as much as possible.
Possible settings of the stop function:
•
"Stop function"
("Low-flow stop
•
function")
●
●
•
), the
min
In start-stop operation, the pressure varies between the start and
stop pressures. See fig. 67.
In "User-defined mode" ("Customised operating mode"), ∆H has
been factory-set to 10 % of the actual setpoint. ∆H can be set
within the range from 5 to 30 % of actual setpoint.
The pump changes to start-stop operation if the flow becomes
lower than the minimum flow.
The minimum flow is set in % of the nominal flow of the pump
(see the pump nameplate).
In "User-defined mode" ("Customised operating mode"), the
minimum flow has been factory-set to 10 % of nominal flow.
no unnecessary heating of the pumped liquid
reduced wear of the shaft seals
reduced noise from operation.
The delivered pressure is not completely constant as it
fluctuates between the start and stop pressures.
The frequent starts/stops of the pump may in some
applications cause acoustic noise.
"Energy-optimal mode"
The pump automatically adjusts the parameters for the stop
function so that the energy consumption during the start-stop
operation period is minimized.
In this case, the stop function uses the factory-set values of
the minimum flow (Q ) and other internal parameters. See
min1
fig. 67.
"High-comfort mode":
The pump automatically adjusts the parameters for the stop
function so that the disturbances during the start-stop
operation period are minimized.
In this case, the stop function uses the factory-set values of
the minimum flow (Q ) and other internal parameters. See
min2
fig. 67.
"User-defined mode" ("Customised operating mode"):
The pump uses the parameters set for ∆H and minimum flow
(Q respectively for the stop function. See fig. 67.
min3)
H
Stop pressure
H
Start pressure
Q
min2
Q
min3
Fig. 67 Difference between start and stop pressures (∆H) and
minimum flow rate
Q
Q
min1
47