Product Manual

Table Of Contents
CU331SP variable frequency drive
SQ, SQE, CU 331, and SP
10
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10. CU331SP variable frequency drive
Features
User interface
The user interface offers these possibilities:
Local operation via a control panel with graphic
display where the menu structure is based on the
well-known system from Grundfos E-pumps.
Monitoring of operating status via indicator lights
and signal relays.
Display of alarm or warning and logging of the last
five alarms and warnings.
Functions
Control mode: Constant pressure
The CU331SP has only one control mode, Constant
pressure. The pressure is kept constant,
independently of the flow rate.
Start-up guide
The CU331SP has a start-up guide, which is launched
at the first power up. Parameters are set manually on
the basis of the installation. The start-up guide can be
repeated, if necessary.
Thanks to the start-up guide, the installer can quickly
set a few parameters and put the CU331SP into
operation.
Direction of rotation test
During start-up, the CU331SP automatically tests and
sets the correct direction of rotation without changing
the cable connections. The direction of rotation test
can be performed manually if it fails for any reason.
Dry-running protection
To protect the pump, the CU331SP will automatically
set up dry-run protection so that water shortage can be
detected. The dry-run alarm will automatically reset 30
minutes after the alarm is declared.
Low-flow stop function
The low-flow stop function is used for changing
between on/off operation at low flow rate and
continuous operation at high flow rate.
The low-flow stop function protects the pump and
saves energy.
Applications
For 4" or larger wells. Main applications:
Domestic and light commercial water supply
irrigation
livestock watering
water transfer.
System components
Compact, efficient, and reliable variable frequency
drive
rugged stainless steel pump end and proven,
reliable, 3-phase motor
pressure sensor
diaphragm tank (sold separately).
Fig. 21 CU331SP variable frequency drive and sensor
TM05 5801 4012