Grundfos CU331SP User manual

GRUNDFOS INSTRUCTIONS
CU331SP
2, 3, 5 Hp
Installation and operating instructions

English (US)
2
English (US) Installation and operating instructions
Original installation and operating instructions.
CONTENTS
Page
1. Limited warranty
Products manufactured by GRUNDFOS PUMPS CORPORATION
(Grundfos) are warranted to the original user only to be free of
defects in material and workmanship for a period of 24 months
from date of installation, but not more than 30 months from date
of manufacture. Grundfos' liability under this warranty shall be
limited to repairing or replacing at Grundfos' option, without
charge, F.O.B. Grundfos' factory or authorized service station,
any product of Grundfos' manufacture. Grundfos will not be liable
for any costs of removal, installation, transportation, or any other
charges which may arise in connection with a warranty claim.
Products which are sold but not manufactured by Grundfos are
subject to the warranty provided by the manufacturer of said
products and not by Grundfos' warranty. Grundfos will not be
liable for damage or wear to products caused by abnormal
operating conditions, accident, abuse, misuse, unauthorized
alteration or repair, or if the product was not installed in
accordance with Grundfos' printed installation and operating
instructions.
To obtain service under this warranty, the defective product must
be returned to the distributor or dealer of Grundfos' products from
which it was purchased together with proof of purchase and
installation date, failure date, and supporting installation data.
Unless otherwise provided, the distributor or dealer will contact
Grundfos or an authorized service station for instructions. Any
defective product to be returned to Grundfos or a service station
must be sent freight prepaid; documentation supporting the
warranty claim and/or a Return Material Authorization must be
included if so instructed.
GRUNDFOS WILL NOT BE LIABLE FOR ANY INCIDENTAL OR
CONSEQUENTIAL DAMAGES, LOSSES, OR EXPENSES
ARISING FROM INSTALLATION, USE, OR ANY OTHER
CAUSES. THERE ARE NO EXPRESS OR IMPLIED
WARRANTIES, INCLUDING MERCHANTABILITY OR FITNESS
FOR A PARTICULAR PURPOSE, WHICH EXTEND BEYOND
THOSE WARRANTIES DESCRIBED OR REFERRED TO
ABOVE.
Some jurisdictions do not allow the exclusion or limitation of
incidental or consequential damages and some jurisdictions do
not allow limit actions on how long implied warranties may last.
Therefore, the above limitations or exclusions may not apply to
you. This warranty gives you specific legal rights and you may
also have other rights which vary from jurisdiction to jurisdiction.
2. Symbols used in this document
1. Limited warranty 2
2. Symbols used in this document 2
3. Introduction 3
3.1 General description 3
3.2 Applications 3
4. Safety and warnings 3
4.1 Warning 3
4.2 Safety regulations 3
4.3 Installation requirements 3
4.4 Reduced performance under certain conditions 3
5. Identification 3
5.1 Nameplate 3
5.2 Packaging label 4
6. Mechanical installation 4
6.1 Reception and storage 4
6.2 Transportation and unpacking 4
6.3 Space requirements and air circulation 4
6.4 Mounting 4
7. Electrical connection 4
7.1 Electrical protection 4
7.2 Mains and motor connection 5
7.3 Connecting the signal terminals 6
7.4 Connecting the signal relays 7
7.5 EMC-correct installation 8
7.6 RFI filters 8
8. Operating modes 8
9. Control mode 8
9.1 Controlled operation (closed loop) 8
10. Menu overview 9
11. Setting by means of the control panel 10
11.1 Control panel 10
11.2 Back to factory setting 10
11.3 Start-up guide 11
11.4 Menu GENERAL 13
11.5 Menu OPERATION 13
11.6 Menu STATUS 14
11.7 Menu INSTALLATION 15
12. Low flow and stop functions 15
13. Maintenance and service 16
13.1 Cleaning the CU331SP 16
13.2 Service parts and service kits 16
14. Fault finding 16
14.1 Warning and alarm list 16
14.2 Resetting of alarms 16
14.3 Indicator lights 17
14.4 Signal relays 17
15. Technical data 17
15.1 Enclosure 17
15.2 Main dimensions and weight 17
17
15.4 Terminal tightening torques 17
15.5 Cable length 18
15.6 Fuses and cable cross-section 18
15.7 Inputs and outputs 18
15.8 Sound pressure level 19
16. Disposal 19
Warning
Prior to installation, read these installation and
operating instructions. Installation and operation
must comply with local regulations and accepted
codes of good practice.
Warning
If these safety instructions are not observed,
it may result in personal injury!
Caution
If these safety instructions are not observed,
it may result in malfunction or damage to the
equipment!
Note
Note
Notes or instructions that make the job easier
and ensure safe operation.

3
English (US)
3. Introduction
This manual introduces all aspects of your Grundfos CU331SP
constant pressure variable frequency drive. Always keep this
manual close to the CU331SP.
3.1 General description
The CU331SP is an external variable frequency drive especially
designed for submersible pumps.
Thanks to the start-up guide in the CU331SP, the installer can
quickly set parameters and put the CU331SP into operation.
Connected to a sensor, the CU331SP will quickly adapt the pump
speed to the actual demand.
3.2 Applications
The CU331SP was developed for use with Grundfos 2, 3, and 5
Hp 4" SP pumps.
The CU331SP provides for constant pressure operation of your
pump across its performance range.
4. Safety and warnings
4.1 Warning
4.2 Safety regulations
• The On/Off button of the control panel does not disconnect the
CU331SP from the power supply and must therefore not be
used as a safety switch.
• The CU331SP must be grounded correctly and protected
against indirect contact according to national regulations.
• The leakage current to ground exceeds 3.5 mA.
• Enclosure class TYPE 12 must not be installed outdoors
without additional protection against water and the sun.
• Always observe national and local regulations as to cable
cross-section, short-circuit protection and over current
protection.
4.3 Installation requirements
The general safety necessitates special considerations as to
these aspects:
• fuses and switches for over current and short-circuit protection
• selection of cables (mains current, motor, load distribution and
relay)
• net configuration (IT, TN, grounding)
• safety on connecting inputs and outputs (PELV).
4.3.1 Aggressive environment
The CU331SP contains a large number of mechanical and
electronic components. They are all vulnerable to environmental
effects.
4.4 Reduced performance under certain conditions
The CU331SP will reduce its performance under these
conditions:
• low air pressure (at high altitude)
• long motor cables.
The required measures are described in the next two sections.
4.4.1 Reduction at low air pressure
PELV = Protective Extra Low Voltage.
At low air pressure, the cooling capacity of air is reduced, and the
CU331SP automatically reduces the performance to prevent
overload.
It may be necessary to select a CU331SP with a higher
performance.
4.4.2 Reduction in connection with long motor cables
The maximum cable length for the CU331SP is 1000 ft (300 m)
for unscreened and 500 ft (150 m) for screened cables. In case of
longer cables, contact Grundfos.
The CU331SP is designed for a motor cable with a maximum
cross-section as stated in section 15.6 Fuses and cable cross-
section.
5. Identification
5.1 Nameplate
The CU331SP can be identified by means of the nameplate. An
example is shown below.
Fig. 1 Example of nameplate
Warning
Any installation, maintenance and inspection
must be carried out by trained personnel.
Warning
Touching the electrical parts may be fatal, even
after the CU331SP has been switched off.
Before making any work on the CU331SP, the
mains supply and other input voltages must be
switched off at least for 7 minutes.
Caution
The CU331SP should not be installed in an
environment where the air contains liquids,
particles or gases which may affect and damage
the electronic components.
Warning
At altitudes above 6600 ft (2000 m), PELV cannot
be met.
TM05 6001 4012
Text Description
T/C: CU-331 (product name)
202P1M2... (internal code)
Prod.no: Product number: 12345678
S/N: Serial number: 123456G234 The last three digits indicate the production date:
23 is the week, and 4 is the year 2004.
2.0 hp Typical shaft power on the motor
IN: Supply voltage, frequency and maximum input
current
OUT: Motor voltage, frequency and maximum output current. The maximum output frequency usually
depends on the pump type.
CHASSIS/
IP20 Enclosure class
Tamb. Maximum ambient temperature

English (US)
4
5.2 Packaging label
The CU331SP can also be identified by means of the label on the
packaging.
6. Mechanical installation
The individual CU331SP cabinet sizes are characterized by their
enclosures. The table in section 15.2 shows the relationship of
enclosure class and enclosure type.
6.1 Reception and storage
Check on receipt that the packaging is intact, and the unit is
complete. In case of damage during transport, contact the
transport company to file a claim.
Note that the CU331SP is delivered in a packaging which is not
suitable for outdoor storage.
6.2 Transportation and unpacking
The CU331SP must only be unpacked at the installation site to
prevent damage during the transport to the site.
The packaging contains accessory bag(s), documentation and
the unit itself. See fig 2.
Fig. 2 CU331SP packaging
6.3 Space requirements and air circulation
CU331SP units can be mounted side by side, but as a sufficient
air circulation is required for cooling these requirements must be
met:
• Sufficient free space above and below the CU331SP.
• Ambient temperature up to 122 °F (50 °C).
• Hang the CU331SP directly on the wall, or fit it with a back
plate. See fig. 3.
Fig. 3 CU331SP hung directly on the wall or fitted with a back
plate
Required free space above and below the CU331SP
For information about enclosure, see 15.1 Enclosure.
6.4 Mounting
1. Mark and drill holes. See 15.2 Main dimensions and weight.
2. Fit the screws, but leave loose. Mount the CU331SP, and
tighten the four screws.
Fig. 4 Drilling of holes
7. Electrical connection
7.1 Electrical protection
7.1.1 Protection against electric shock, indirect contact
Protective conductors must always have a yellow/green (PE) or
yellow/green/blue (PEN) color marking.
Instructions according to EN IEC 61800-5-1:
• The CU331SP must be stationary, installed permanently and
connected permanently to the mains supply.
• The ground connection must be carried out with duplicate
protective conductors or with a single reinforced protective
conductor with a cross-section of minimum AWG 7 (10 mm2).
7.1.2 Protection against short-circuit, fuses
The CU331SP and the supply system must be protected against
short-circuit.
Grundfos requires that the back-up fuses mentioned in15.6 Fuses
and cable cross-section are used for protection against short-
circuit.
The CU331SP offers complete short-circuit protection in case of a
short-circuit on the motor output.
TM05 5990 4012TM03 8859 2607
Accessory bag
Enclosure Space [in (mm)]
B1 7.9 (200)
Caution
The user is responsible for mounting the
CU331SP securely on a firm surface.
TM03 8860 2607
Warning
The owner or installer is responsible for ensuring
correct grounding and protection according to
national and local standards.
Warning
Before making any work on the CU331SP, the
mains supply and other voltage inputs must be
switched off for at least as long as stated in
section 4. Safety and warnings.
Caution
The leakage current to ground exceeds 3.5 mA,
and a reinforced ground connection is required.
b
a
a
b

5
English (US)
7.1.3 Additional protection
If the CU331SP is connected to an electrical installation where an
earth leakage circuit breaker (ELCB) is used as additional
protection, the circuit breaker must be of a type marked with the
following symbols:
The circuit breaker is type B.
The total leakage current of all the electrical equipment in the
installation must be taken into account.
The leakage current of the CU331SP in normal operation can be
seen in section 15.7.1 Mains supply (L1, L2).
During start and in asymmetrical supply systems, the leakage
current can be higher than normal and may cause the ELCB to
trip.
7.1.4 Motor protection
The motor requires no external motor protection. The CU331SP
protects the motor against thermal overloading and blocking.
7.1.5 Protection against overcurrent
The CU331SP has an internal overcurrent protection for overload
protection on the motor output.
7.1.6 Protection against mains voltage transients
The CU331SP is protected against mains voltage transients
according to EN 61800-3, second environment.
7.2 Mains and motor connection
The supply voltage and frequency are marked on the CU331SP
nameplate. Make sure that the CU331SP is suitable for the power
supply of the installation site.
7.2.1 Mains switch
A mains switch can be installed before the CU331SP according to
local regulations. See fig. 5.
7.2.2 Wiring diagram
The wires in the terminal box must be as short as possible.
Excepted from this is the protective conductor which must be so
long that it is the last one to be disconnected in case the cable is
inadvertently pulled out of the cable entry.
Fig. 5 CU331SP wiring diagram
Mains connection
1. Connect the ground wire to terminal 95 (PE). See fig. 6.
2. Connect the power leads to the terminals 91 (L1), 92 (L2).
3. Fix the mains cable with a cable clamp.
Fig. 6 Mains connection
Motor connection
1. Connect the ground wire to terminal 99 (PE). See fig. 7.
2. Connect the motor leads to the terminals 96 (U), 97 (V), 98
(W).
3. Fix the screened cable with a cable clamp.
Fig. 7 Motor connection
Caution
The leakage current to ground exceeds 3.5 mA.
Note
Note
The maximum output voltage of the CU331SP is
equal to the input.
Example: if the supply voltage is rated at 208V
choose a 208V motor for operation.
TM05 5867 3912
Terminal Function
91 (L1) Single-phase supply
92 (L2)
95/99 (PE) Ground connection
ELCB
Note
Note
For single-phase connection, use L1 and L2.
Caution
Check that mains voltage and frequency
correspond to the values on the nameplate of the
CU331SP and the motor.
Note
Note
CU331SP drive is usable with 3-phase input
power by connecting leads to 91 (L1), 92 (L2), and
93 (L3).
Caution
The motor cable must be screened for the
CU331SP to meet EMC requirements.
TM03 9020 2807

English (US)
6
7.3 Connecting the signal terminals
Connect the signal cables according to the guidelines for good
practice to ensure EMC-correct installation. See 7.5 EMC-correct
installation.
• Use screened signal cables with a conductor cross-section of
min. AWG 20 (0.5 mm2) and max. AWG 16 (1.5 mm2).
• Use a 3-conductor screened bus cable in new systems.
7.3.1 Minimum connection, signal terminal
Operation is only possible when the terminals 18 and 20 are
connected, for instance by means of an external On/Off switch or
a short wire.
Fig. 8 Required minimum connection, signal terminal
Fig. 9 Wiring diagram for CU331SP
Fig. 10 Sensor wiring diagram
7.3.2 Setting the analog input 54
The contact A54 is positioned behind the control panel and is
used for setting the signal type of the analog input.
The factory setting of the inputs is voltage signal "U". This setting
must be changed to "I" prior to starting the CU331SP. Be sure the
power supply is switched off.
Remove the control panel to set the contact. See fig. 11.
Fig. 11 Setting contact A54 to current signal "I"
Note
Note
The cable screen must be exposed and in
physical contact with the mounting plate and
clamp
Caution
As a precaution, signal cables must be separated
from other groups by reinforced insulation in
their entire lengths.
Note
Note
If no external On/Off switch is connected, short-
circuit terminals 18 and 20 using a short wire.
TM03 9057 3207
Start/stop
GND
Jumper wire
TM05 5802 3913
TM05 6776 5112
Note
Note
Switch off the power supply before setting the
A54.
TM05 5803 3912
0/4-20 mA
Terminals
Sensor 1
GND
GND
+24 V out Start/stop
RS-485 GND Y
RS-485 B
RS-485 A
Switch position
must be
changed to "I"
prior to startup
Jumper wire
UI
A54

7
English (US)
7.3.3 Terminal Key
7.3.4 Access to signal terminals
All signal terminals are behind the terminal cover of the CU331SP
front. Remove the terminal cover as shown in Fig.12.
Fig. 12 Access to signal terminals
Fig. 13 Signal terminals
7.3.5 Fitting the conductor
1. Remove the insulation at a length of 0.35 to 0.40 inches (9 to
10 mm).
2. Insert a screwdriver with a tip of maximum 0.015 X 0.1 in (0.4
X 2.5 mm) into the square hole.
3. Insert the conductor into the corresponding round hole.
Remove the screwdriver. The conductor is now fixed in the
terminal.
Fig. 14 Fitting the conductor into the signal terminal
7.4 Connecting the signal relays
Fig. 15 Terminals for signal relays (normal state, not activated)
7.4.1 Signal Relay
The signal relays on the CU331SP are predefined as follows:
Relay 1: Pump running
Relay 2: Alarm.
Fig. 16 Terminals for relay connection
Terminal Type Function
12 +24 V out Supply to sensor
18 DI 1 Digital input, start/stop
20 GND Common frame for digital inputs
55 GND Common frame for analog inputs
54 AI 2 Sensor input, sensor 1, 0/4-20 mA
61 RS-485 GND Y GENIbus, frame
68 RS-485 A GENIbus, signal A (+)
69 RS-485 B GENIbus, signal B (-)
Note
Note
The RS-485 screen must be connected to frame.
TM03 9004 2807
TM03 9025 2807
TM03 9026 2807
Caution
As a precaution, signal cables must be separated
from other groups by reinforced insulation in
their entire lengths.
TM03 8801 2507
Terminal Function
C1C2Common
NO 1 NO 2 Normally open contact
NC 1 NC 2 Normally closed contact
TM03 9008 2807
C 1
NC 1
NO 1
NC 2
NO 2
C2

English (US)
8
7.5 EMC-correct installation
This section gives guidelines for good practice when installing the
CU331SP. Follow these guidelines to meet EN 61800-3, first
environment.
• Use only motor and signal cables with a braided metal screen
in applications without output filter.
• There are no special requirements to supply cables, apart
from local requirements.
• Leave the screen as close to the connecting terminals as
possible. See fig. 17.
• Avoid terminating the screen by twisting the ends. See fig.18
18. Use cable clamps or EMC screwed cable entries instead.
• Connect the screen to frame at both ends for both motor and
signal cables. If the controller has no cable clamps, connect
only the screen to the CU331SP.
• Avoid unscreened motor and signal cables in electrical
cabinets with variable frequency drives.
• Make the motor cable as short as possible in applications
without output filter to limit the noise level and minimise
leakage currents.
• Screws for frame connections must always be tightened
whether a cable is connected or not.
• Keep main cables, motor cables and signal cables separated
in the installation, if possible.
Other installation methods may give similar EMC results if the
above guidelines for good practice are followed.
7.6 RFI filters
To meet the EMC requirements, the CU331SP comes with the
following types of built-in radio frequency interference filter (RFI).
*Single-phase input - three-phase output.
Description of RFI filter types
RFI filter types are according to EN61800-3
Fig. 17 Example of stripped cable with screen
Fig. 18 Do not twist the screen ends
8. Operating modes
The following operating modes are set on the control panel in
menu OPERATION, display 1.2. See 11.5.2 Operating mode
(1.2).
Example: Max. curve operation can for instance be used in
connection with venting the pump during installation.
Example: Min. curve operation can for instance be used in
periods with a very small flow requirement.
9. Control mode
The control mode of the CU331SP is:
• Controlled operation (closed loop) with a sensor connected.
9.1 Controlled operation (closed loop)
Voltage Typical shaft power P2 RFI filter type
1 x 200-240 V * 1.5 - 10 hp C1
C1: For use in domestic areas.
TM02 1325 0901TM03 8812 2507
Operating mode Description
Normal The pump is running in the control mode
selected
Stop The pump has been stopped (green indicator
light is flashing)
Min. The pump is running at minimum speed
Max. The pump is running at maximum speed
TM03 8813 2507
Min. and max. curves.
The pump speed is kept at a given
set value for minimum and maximum
speed, respectively.
Note
Note
This cannot be changed
TM03 8476 1607 TM03 8805 2507
Constant pressure.
The pressure is
kept constant,
independently of
the flow rate.
Min.
Max.
CU331SP
p

9
English (US)
10. Menu overview
Fig. 19 Menu overview
START-UP GUIDE 0. GENERAL 1. OPERATION 2. STATUS 3. INSTALLATION
0.11.12.13.1
1/11 0.2 1.2 2.2 3.2
2/11 1.3 2.3 3.3
1.4 2.4 3.4
3/11-7/11
Automatic or manual
setting of the direction
of rotation
8/11 1.5 - 1.9 2.5 3.5
2.6
9/11-10/11
Automatic setting of
Stop and Dry-run
functions
11/11 1.10-1.14 2.7
2.11
2.12

English (US)
10
Menu structure
The CU331SP has a start-up guide, which is started at the first
start-up. After the start-up guide, the CU331SP has a menu
structure divided into four main menus:
1. GENERAL gives access to the start-up guide for the general
setting of the CU331SP.
2. OPERATION enables the setting of setpoint and resetting of
alarms. It is also possible to see the latest five warnings and
alarms.
3. STATUS shows the status of the CU331SP and the pump. It is
not possible to change or set values.
4. INSTALLATION gives access to available parameters.
11. Setting by means of the control panel
11.1 Control panel
The control panel is used for local setting of the CU331SP. The
functions available are preset in the CU331SP.
Fig. 20 Control panel of the CU331SP
Editing buttons
Navigating buttons
Adjusting the display contrast
Press OK and + for darker display.
Press OK and - for brighter display.
Button lock
To lock the buttons on the panel press and hold the up and down
arrows simultaneously.
Indicator lights
The operating condition of the pump is indicated by the indicator
lights on the front of the control panel. See fig. 20.
The table shows the function of the indicator lights.
Displays, general terms
Figures 21 and 22 show the general terms of the display.
Fig. 21 Example of display in the start-up guide
Fig. 22 Example of display in the user menu
11.2 Back to factory setting
Follow this procedure to get back to the factory setting:
1. Switch off the power supply to the CU331SP.
2. Press On/Off, OK and + while switching on the power supply.
The CU331SP will reset all parameters to factory settings. The
display will turn on when the reset is completed.
Warning
The On/Off button on the control panel does not
disconnect the CU331SP from the power supply
and must therefore not be used as a safety
switch.
The On/Off button has the highest priority. In
"Off" condition, pump operation is not possible.
TM03 8719 2507
Button Function
Makes the pump ready for operation/starts and
stops the pump.
Saves changed values, resets alarms and expands
the value field.
Changes values in the value field.
On/On/
Off
+
-
CU
CUE
>
>
>
>
OK
On/
On/
Off
On
On
Off
Alarm
Alarm
On/On/
Off
OK
+
-
Button Function
Navigates from one menu to another. When the
menu is changed, the display shown will always be
the top display of the new menu.
Navigates up and down in the individual menu.
Indicator
light Function
On (green)
The pump is running or has been stopped by a
stop function.
If flashing, the pump has been stopped by the
user (CU331SP menu), external start/stop or
bus.
Off (orange) The pump has been stopped with the On/Off
button.
Alarm (red) Indicates an alarm or a warning.
>
>
>
>
Display name
Current display / total number
Value field
Display name
Display number, menu name
Value field

11
English (US)
11.3 Start-up guide
Use the start-up guide for the general setting of the CU331SP
including the setting of the correct direction of rotation.
The start-up guide is started the first time when the CU331SP is
connected to the power supply. It can be restarted in menu
GENERAL. Please note that in this case all previous settings will
be erased.
Bulleted lists show possible settings. Factory settings are shown
in bold.
11.3.1 Welcoming display
• Press OK. You will now be guided through the start-up guide.
11.3.2 Language
Select the language to be used in the display:
•EnglishUS
• French
• Spanish.
11.3.3 Supply Voltage
Select supply voltage according to the rated supply voltage of the
installation site.
Unit 1 X 200-240 V
• 1 X 200 V
• 1 X 208 V
• 1 X 220 V
• 1 X 230 V
• 1 X 240 V
11.3.4 Priming and venting
See the installation and operating instructions of the pump.
The general setting of the CU331SP is now completed, and the
start-up guide is ready for setting the direction of rotation:
• Press OK to go on to automatic or manual setting of the
direction of rotation.
11.3.5 Automatic setting of the direction of rotation
The CU331SP automatically tests and sets the correct direction
of rotation without changing the cable connections.
This test is not suitable for certain pump types and will in certain
cases not be able to determine for certainty the correct direction
of rotation. In these cases, the CU331SP changes over to manual
setting where the direction of rotation is determined on the basis
of the installer’s observations.
Information displays.
• Press OK to continue.
The pump starts after 10 seconds.
It is possible to interrupt the test and return to the previous
display.
The pump runs with both directions of rotation and stops
automatically.
It is possible to interrupt the test, stop the pump and go to manual
setting of the direction of rotation.
Note
Note
Check that equipment connected is ready for
start-up, and that the CU331SP has been
connected to the power supply.
Have nameplate data for motor, pump and
CU331SP at hand. Warning
During the test, the pump will run for a short
time. Ensure no personnel or equipment is in
danger!
The correct direction of
rotation has now been set.
• Press OK to set the setpoint
(8/11) See 11.3.6 Setpoint
The automatic setting of the
direction of rotation has failed.
• Press OK to go to manual
setting of the direction of
rotation.

English (US)
12
11.3.6 Setpoint
Set the setpoint according to the desired discharge pressure
11.3.7 Setting the stop and dry -run functions
The CU331SP automatically determines and sets the stop and dr-
run functions for the pump and motor combination
Information displays. Assure all discharge valves in the system
are closed so that no water can flow.
• press OK to continue.
The pump will run against the closed valves and determine the
power settings for the Stop and Dry-Run functions.
It is possible to cancel this operation and start over in case of a
problem such as a water leak. The setup cannot be completed
without running this test.
11.3.8 General settings are completed
• Press OK to make the pump ready for operation or start the
pump in the operating mode Normal. Then display 1.1 of menu
OPERATION will appear.
11.3.9 Manual setting when the direction of rotation is not
visible
It must be possible to observe the pressure.
Information displays.
• Press OK to continue.
The pump starts after 10 seconds.
It is possible to interrupt the test and return to the previous
display.
The pressure will be shown during the test if a pressure sensor is
connected. The motor current is always shown during the test.
The first test is completed.
• Write down the pressure and/or flow rate, and press OK to
continue the manual test with the opposite direction of
rotation.
The pump starts after 10 seconds.
It is possible to interrupt the test and return to the previous
display.
The pressure will be shown during the test if a pressure sensor is
connected. The motor current is always shown during the test.
Warning
During the test, the pump will run for a short
time. Ensure no personnel or equipment is in
danger!

13
English (US)
The second test is completed.
Write down the pressure and/or flow rate, and state which test
gave the highest pump performance:
• First test
• Second test
• Make new test.
The correct direction of rotation has now been set.
• Press OK to set the setpoint (8/11). See 11.3.6 Setpoint.
11.4 Menu GENERAL
The menu makes it possible to return to the start-up guide, which
is usually only used during the first start-up of the CU331SP.
11.4.1 Return to start-up guide (0.1)
State your choice:
•Yes
•No.
• If Yes is selected, all settings will be erased, and the entire
start-up guide must be completed.
11.4.2 Type code change (0.2)
This display is for service use only.
11.5 Menu OPERATION
11.5.1 Setpoint (1.1)
Setpoint set
Actual setpoint
Actual value
Set the setpoint in units of the feedback sensor.
11.5.2 Operating mode (1.2)
Set one of the following operating modes:
•Normal
•Max
•Min
•Stop
The operating modes can be set without changing the setpoint
setting.
11.5.3 Fault indications
Faults may result in two types of indication: Alarm or warning.
An "alarm" will activate an alarm indication in CU331SP and
cause the pump to change operating mode, typically to stop.
However, for some faults resulting in alarm, the pump is set to
continue operating even if there is an alarm.
A "warning" will activate a warning indication in CU331SP, but
the pump will not change operating or control mode.
Alarm (1.3)
In case of an alarm, the cause will appear in the display. See
14.1 Warning and alarm list.
Warning (1.4)
In case of warning, the cause will appear in the display. See
section 14.1 Warning and alarm list.
11.5.4 Fault log
For both fault types, alarm and warning, the CU331SP has a log
function.
Alarm log (1.5-1.9)
In case of an "alarm", the last five alarm indications will appear in
the alarm log. "Alarm log 1" shows the latest alarm, "Alarm log 2"
shows the latest alarm but one, etc.
The display shows three pieces of information:
• the alarm indication
• the alarm code
• the number of minutes the pump has been connected to the
power supply after the alarm occurred.
Note
Note
If the start-up guide is started, all previous
settings will be erased!
Note
Note
The start-up guide must be carried out on a cold
motor!
Repeating the start-up guide may lead to a
heating of the motor.

English (US)
14
Warning log (1.10 - 1.14)
In case of a "warning", the last five warning indications will
appear in the warning log. "Warning log 1" shows the latest fault,
"Warning log 2" shows the latest fault but one, etc.
The display shows three pieces of information:
• the warning indication
• the warning code
• the number of minutes the pump has been connected to the
power supply after the warning occurred.
11.6 Menu STATUS
The displays appearing in this menu are status displays only. It is
not possible to change or set values.
The tolerance of the displayed value is stated under each display.
The tolerances are stated as a guide in % of the maximum values
of the parameters.
11.6.1 Actual setpoint (2.1)
This display shows the actual setpoint and the external setpoint.
The actual setpoint is shown in units of feedback sensor.
The external setpoint is not used with the CU331SP.
11.6.2 Operating mode (2.2)
This display shows the actual operating mode (Normal, Stop, Min.
or Max.). Furthermore, it shows where this operating mode was
selected (CU331SP menu, Bus, External or On/Off button).
11.6.3 Actual value (2.3)
This display shows the actual value controlled.
11.6.4 Measured value, sensor 1 (2.4)
This display shows the actual value measured by sensor 1
connected to terminal 54.
If no sensor is connected to the CU331SP, "-" will appear in the
display.
11.6.5 Speed (2.5)
Tolerance: ± 5 %
This display shows the actual pump speed.
11.6.6 Input power and motor current (2.6)
Tolerance: ± 10 %
This display shows the actual pump input power in W or kW and
the actual motor current in Ampere [A].
11.6.7 Operating hours and power consumption (2.7)
Tolerance: ± 2 %
This display shows the number of operating hours and the power
consumption. The value of operating hours is an accumulated
value and cannot be reset. The value of power consumption is an
accumulated value calculated from the unit’s birth, and it cannot
be reset.
11.6.8 Firmware Version (2.11)
This display shows the version of the software.
11.6.9 Configuration file
This display shows the configuration file.
Note
Note
For reference only, actual software version
number will differ.

15
English (US)
11.7 Menu INSTALLATION
11.7.1 Sensor 1 (3.1)
Setting of sensor 1 connected to terminal 54. This is the feedback
sensor.
Select among the following values:
• Sensor output signal:
0-20 mA
4-20 mA.
• Unit of measurement of sensor:
psi
• Sensor measuring range:
0-120 psi
11.7.2 Motor speed high limit (3.2)
This parameter allows the user to limit the maximum speed that
the motor can operate.
Setting range is 1800 rpm to 3450 rpm.
11.7.3 Dry pump function (3.3)
This display shows the setting for how the Dry-Run indication
should be handled by the drive. This parameter can be set to
these values:
•OFF
• Warning
•Alarm
The default setting is “Alarm” which will stop the motor to protect
the pump. When “Warning” is selected the drive will provide a
Dry-Run warning on the display screen only and the pump will
continue to run. When “OFF” is selected the Dry-Run function is
disabled. Neither a warning nor alarm will be issued.
11.7.4 Power correction factor (3.4)
Power Correction Factor is used to adjust the sensitivity of the
Dry-Run function. Contact Grundfos for assistance if it is
necessary to adjust this parameter.
11.7.5 Protocol (3.5)
This display shows the protocol selection for the RS-485 port of
the CU331SP. The protocol can be set to these values:
•GENIbus
•FC
•FCMC.
If GENIbus is selected, the communication is set according to the
Grundfos GENIbus standard. FC and FC MC is for service
purpose only.
12. Low flow and stop functions
1. Low-flow detection function
The pump will check the flow regularly by reducing the speed for
a short time. If there is no or only a small change in pressure, this
means that there is low flow.
The speed will be increased until the stop pressure (actual
setpoint + 0.5 x ΔH) is reached and the pump will stop after a few
seconds. The pump will restart at the latest when the pressure
has fallen to the start pressure (actual setpoint - 0.5 x ΔH).
If the flow in the off period is higher than the low-flow limit, the
pump will restart before the pressure has fallen to the start
pressure.
When restarting, the pump will react in the following way:
1. If the flow is higher than the low-flow limit, the pump will return
to continuous operation at constant pressure.
2. If the flow is lower than the low-flow limit, the pump will
continue in start/stop operation. It will continue in start/stop
operation until the flow is higher than the low-flow limit. When
the flow is higher than the low-flow limit, the pump will return
to continuous operation.
Operating conditions for the stop function
It is only possible to use the stop function if the system
incorporates a pressure sensor, a non-return valve and a
diaphragm tank.
Note
Note
If the Dry Pump Function setting is changed to
“Warning” or “OFF” the drive will not stop motor
operation and there is a risk of damage to the
pump. This is not recommended by Grundfos.
Note
Note
Changing this parameter may cause the Dry-Run
function to stop working and therefore put the
pump at risk for damage. Use caution when
making adjustments to this parameter.
Caution
The non-return valve must always be installed
before the pressure sensor.

English (US)
16
Fig. 23 Position of the pressure sensor and diaphragm tank
Diaphragm tank
The stop function requires a diaphragm tank of a certain minimum
size. The tank must be installed as close as possible after the
pump and the precharge pressure must be 0.7 x actual setpoint.
Recommended diaphragm tank size:
If a diaphragm tank of the above size is installed in the system,
the factory setting of ΔH is the correct setting.
If the tank installed is too small, the pump will start and stop too
often.
13. Maintenance and service
13.1 Cleaning the CU331SP
Keep the cooling fins and fan blades clean to ensure sufficient
cooling of the CU331SP.
13.2 Service parts and service kits
For further information on service parts and service kits, visit
www.grundfos.us > website> WebCAPS.
14. Fault finding
14.1 Warning and alarm list
1) In case of an alarm, the CU331SP will change the operating
mode depending on the pump type.
2) Warning is reset in display 3.20.
14.2 Resetting of alarms
In case of fault or malfunction of the CU331SP, check the alarm
list in menu OPERATION. The latest five alarms and latest five
warnings can be found in the log menus.
Contact a Grundfos technician if an alarm occurs repeatedly.
14.2.1 Warning
The CU331SP will continue the operation as long as the warning
is active. The warning remains active until the cause no longer
exists. Some warnings may switch to alarm condition.
14.2.2 Alarm
In case of an alarm, the CU331SP will stop the pump or change
the operating mode depending on the alarm type and pump type.
See 14.1 Warning and alarm list.
Pump operation will be resumed when the cause of the alarm has
been remedied and the alarm has been reset.
The CU331SP has an automatic reset function for all alarms
(except "Locked Alarm" as listed above.) The automatic reset
time is 10 seconds for all alarms except Dry-Run. The Dry-run
alarm will reset after 30 minutes.
TM05 5804 3912
Rated flow rate of pump
[gpm (m3/h)] Typical diaphragm tank size
[gallon (L)]
0-26 (0-6) 2 (7.5)
27-105 (7-24) 4.4 (16.7)
Pressure sensor
Diaphragm tank
Pump with non return valve
Code and display text
Status
Operat-
ing mode Reset- ting
Warning Alarm Locked alarm
1Too high leakage
current ●Stop Man.
2 Mains phase failure ●Stop Aut.
3 External fault ●Stop Man.
16 Other fault ●Stop Aut.
●Stop Man.
32 Overvoltage ●-Aut.
●Stop Aut.
40 Undervoltage ●-Aut.
●Stop Aut.
48 Overload ●Stop Aut.
●Stop Man.
49 Overload ●Stop Aut.
55 Overload ●-Aut.
●Stop Aut.
57 Dry running ●Stop Aut.
64 Too high CU331SP
temperature ●Stop Aut.
89 Sensor 1 outside range ●1) Aut.
96 Setpoint signal outside
range ●1) Aut.
155 Inrush fault ●Stop Aut.
241 Motor phase failure ●-Aut.
●Stop Aut.

17
English (US)
Resetting an alarm manually
• Press OK in the alarm display.
• Press On/Off twice.
• Activate a digital input DI 1 (Start/stop).
If it is not possible to reset an alarm, the reason may be that the
fault has not been remedied, or that the alarm has been locked.
14.2.3 Locked alarm
In case of a locked alarm, the CU331SP will stop the pump and
become locked. Pump operation cannot be resumed until the
cause of the locked alarm has been remedied and the alarm has
been reset.
Resetting a locked alarm
• Switch off the power supply to the CU331SP for approx.
30 seconds. Switch on the power supply, and press OK in the
alarm display to reset the alarm.
14.3 Indicator lights
The table show the function of the indicator lights.
14.4 Signal relays
The table show the function of the signal relays.
15. Technical data
15.1 Enclosure
All CU331SP enclosures are size B1. The enclosure rating can
be either IP 55 / TYPE 12 or IP 66 / TYPE 4X
15.2 Main dimensions and weight
1) The dimensions are maximum height, width and depth.
15.3 Surroundings
15.4 Terminal tightening torques
Indicator
light Function
On (green)
The pump is running or has been stopped by a
stop function.
If flashing, the pump has been stopped by the
user (CU331SP menu), external start/stop or
bus.
Off (orange) The pump has been stopped with the On/Off
button.
Alarm (red) Indicates an alarm or a warning.
Type Function
Relay 1 • Pump running
Relay 2 •Alarm
TM03 9002 2807
Fig. 24 Enclosure B1
Enclo-
sure Height [in] Width [in] Depth [in]
B1
AaBbC
18.9 17.9 9.5 8.3 10.2
Screw holes [in] Weight
[lbs]
cdef
0.47 0.75 0.35 0.35 50.7
Relative humidity 5-95 % RH
Ambient temperature Max. 122 °F
(50 °C)
Average ambient temperature over 24 hours Max. 113 °F
(45 °C)
Minimum ambient temperature at full
operation 32 °F (0 °C)
Minimum ambient temperature at reduced
operation 14 °F (-10 °C)
Temperature during storage and
transportation -13 to 150 °F (-25 to 65 °C)
Storage duration Max. 6 months
Maximum altitude above sea level without
performance reduction 3280 ft (1000 m)
Maximum altitude above sea level with
performance reduction 9840 ft (3000 m)
Note
Note
The CU331SP comes in a packaging which is not
suitable for outdoor storage.
Enclosure Tightening torque [ft-lb]
Mains Motor Earth Relay
B1 1.3 1.3 2.2 0.4

English (US)
18
15.5 Cable length
15.6 Fuses and cable cross-section
15.6.1 Cable cross-section to signal terminals
15.6.2 Non-UL fuses and conductor cross-section to mains
and motor
1) Screened motor cable, unscreened supply cable.
15.6.3 UL fuses and conductor cross-section to mains and
motor
1) Screened motor cable, unscreened supply cable.
15.7 Inputs and outputs
15.7.1 Mains supply (L1, L2)
15.7.2 Motor output (U, V, W)
1) Output voltage in % of supply voltage.
15.7.3 RS-485 GENIbus connection
The RS-485 circuit is functionally separated from other central
circuits and galvanically separated from the supply voltage
(PELV).
15.7.4 Digital inputs
All digital inputs are galvanically separated from the supply
voltage (PELV) and other high-voltage terminals.
15.7.5 Signal relays
1) IEC 60947, parts 4 and 5.
The relay contacts are galvanically separated from other circuits
by reinforced insulation (PELV).
Maximum length, screened motor cable 500 ft (152 m)
Maximum length, unscreened motor cable 1000 ft (305 m)
Maximum length, signal cable 1000 ft (305 m)
Warning
Always comply with national and local
regulations as to cable cross-sections.
Maximum cable cross-section to signal
terminals, rigid conductor AWG 14
Maximum cable cross-section to signal
terminals, flexible conductor AWG 18
Minimum cable cross-section to signal
terminals AWG 20
Typical shaft
power P2
[Hp]
Maximum
fuse size
[A]
Fuse
type
Maximum conductor
cross section1
AWG [mm2]
240gG710
340gG710
580gG710
Typical shaft
power P2
[Hp]
Maximum
fuse size
[A]
Bussmann
RK1
Maximum conductor
cross section1
[AWG]
240KTN-R40 7
340KTN-R40 7
580KTN-R80 7
Supply voltage 200-240 V ± 10 %
Supply frequency 60 Hz
Maximum temporary imbalance between
phases 3 % of rated value
Leakage current to earth > 3.5 mA
Number of cut-ins Max. 1 time/min.
Note
Note
Do not use the power supply for switching the
CU331SP on and off.
Output voltage 0-100 % 1)
Output frequency 0-60 Hz
Switching on output Not recommended
Terminal number 68 (A), 69 (B), 61 GND (Y)
Terminal number 18
Voltage level 0-24 VDC
Voltage level, open contact > 19 VDC
Voltage level, closed contact < 14 VDC
Maximum voltage on input 28 VDC
Input resistance, RiApprox. 4 kΩ
Relay 01, terminal number 1 (C), 2 (NO), 3 (NC)
Relay 02, terminal number 4 (C), 5 (NO), 6 (NC)
Maximum terminal load (AC-1) 1) 240 VAC, 2 A
Maximum terminal load (AC-15) 1) 240 VAC, 0.2 A
Maximum terminal load (DC-1) 1) 50 VDC, 1 A
Minimum terminal load 24 V DC 10 mA
24 V AC 20 mA
C Common
NO Normally open
NC Normally closed

19
English (US)
15.7.6 Analog input
1) The factory setting is voltage signal "U".
All analog inputs are galvanically separated from the supply
voltage (PELV) and other high-voltage terminals.
15.8 Sound pressure level
The sound pressure of the CU331SP is maximum 70 dB(A).
The sound pressure level of a motor controlled by a Variable
frequency drive may be higher than that of a corresponding motor
which is not controlled by a variable frequency drive.
16. Disposal
This product or parts of it must be disposed of in an
environmentally sound way:
1. Use the public or private waste collection service.
If this is not possible, contact the nearest Grundfos company or
service workshop.
Subject to alterations.
Terminal number 54
Current signal A54 = "I" 1)
Current range 0-20, 4-20 mA
Input resistance, RiApprox. 200 Ω
Maximum current 30 mA
Maximum fault, terminals 53, 54 0.5 % of full scale

20