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4.4 Settings
For a detailed description of the Grundfos GO
displays, see section
14. CU 300 with Grundfos
4.4.1 Required Grundfos GO settings
If the maximum speed of the pump has been reduced
-1
by more than 1000 min
, the dry-running stop value
must be changed. In order to change the dry-running
protection function, you must make the following
Grundfos GO settings.
1. Set "Dry-running protection" to "Active".
In certain installations, it may be
necessary to disable the dry-running
protection. The disabling applies to the
dry-running power limit set in the
display
Dry-running
Pump power input
Set the dry-running power limit in the display
running stop
by following the procedure below:
•
Start the pump against a closed discharge pipe.
•
Read the input power (P1) in the display
consumption.
•
Calculate the dry-running power limit: P1 x 0.9
[W].
•
Set this value in the display
Related information
15.1.9 Power consumption
15.2.21 Dry-running stop
4.5 Description of the dewatering function
When the pump sucks air, the pump power input
decreases.
If the pump power input falls below the dry-running
power limit set in the display
stop, the pump will stop.
During dewatering, the green indicator light in the
On/Off button on CU 300 is flashing to indicate that
the pump has stopped.
Related information
15.2.21 Dry-running stop
15.2.18 Dewatering
15.2.19 Dewatering, maximum "On" and "Off" time
15.2.21 Dry-running stop
4.5.1 Applications
You can use the dewatering function in applications
where the pump often runs dry, e.g.:
•
In boreholes with a low yield.
•
In boreholes and building sites where the water
table should be lowered.
10
GO.
stop. See fig.
curve.
Dry-
Power
Dry-running
stop.
15.2.21 Dry-running
4.5.2 Function
The dewatering function works as follows:
1. The pump is operating.
2. The pump sucks air due to a drop in the water
level.
3. The load decreases, and consequently the pump
power input does as well.
4. The pump stops when the power input falls to the
dry-running power limit set in the Grundfos GO
display
Dry-running
stop.
The length of the stop time depends on
the setting you have made in the
Grundfos GO display "Dewatering max
off time". See section
maximum "On" and "Off"
Related information
15.2.21 Dry-running stop
15.2.19 Dewatering, maximum "On" and "Off" time
4.5.3 Required Grundfos GO settings
In order to activate the dewatering function, you must
make the following Grundfos GO settings:
1. Set "Dry-running protection" to "Active".
2. Set the dry-running power limit, i.e. dry-running
stop. See "Setting of dry-running power limit (dry-
running stop)" below.
3. Set the relation between run and stop times.
Indication of operation:The dry-running alarm
indication on CU 300 is automatically disabled,
when you make the setting in the display
Dewatering, maximum "On" and "Off"
To disable the dewatering function and return to
dry-running protection, simply disable the
"Dewatering" function in the display Dewatering.
Setting of dry-running power limit (dry-running
stop):
1. Start the pump against a closed discharge pipe.
2. Read the input power (P1) in the display
consumption.
3. Calculate the dry-running power limit: P1 x 0.9
[W].
4. Set this value in the display
Related information
15.1.9 Power consumption
15.2.21 Dry-running stop
15.2.19 Dewatering, maximum "On" and "Off" time
15.2.18 Dewatering
Dewatering,
time.
time.
Power
Dry-running
stop.
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