Grundfos CU 300 User manual

CU 300
Installation and operating instructions
No contact
Overvoltage
Undervoltage
Dry running
Speed reduction
Overtemperature
Overload
Sensor alarm
CU 300
Installation and operating instructions
http://net.grundfos.com/qr/i/96427972
GRUNDFOS INSTRUCTIONS

3

English (GB) Installation and operating instructions
Original installation and operating instructions
Table of contents
1. General information ............. 5
1.1 Hazard statements .............. 5
1.2 Notes ..................... 5
2. General .................... 6
2.1 Expansion possibilities ............ 6
2.2 On/Off button ................. 6
3. Mechanical installation ........... 7
3.1 Location .................... 7
3.2 Mounting CU 300 ............... 7
4. CU 300 as an alarm unit........... 7
4.1 Description .................. 7
4.2 Electrical installation ............. 8
4.3 Description of dry-running protection..... 9
4.4 Settings ....................10
4.5 Description of the dewatering function ....10
5. CU 300 with constant-pressure control
- 0 to 6 bar ..................12
5.1 Description ..................12
5.2 Function ....................12
5.3 Positioning the pressure sensor .......14
5.4 System sizing .................14
5.5 Electrical installation .............15
5.6 Startup.....................16
6. CU 300 with constant-pressure control
- 0 to 10 bar..................17
6.1 Description ..................17
6.2 Function ....................17
6.3 Positioning the pressure sensor .......18
6.4 System sizing .................18
6.5 Electrical installation .............19
6.6 Startup.....................20
7. CU 300 with constant-pressure control
- two-pump operation ............21
7.1 Description ..................21
7.2 Function ....................21
7.3 Positioning the pressure sensor .......22
7.4 System sizing .................22
7.5 Electrical installation .............23
7.6 Startup.....................24
8. CU 300 with sensors ............25
8.1 General ....................25
8.2 Sensor functioning ..............26
8.3 Electrical installation .............27
9. CU 300 connected to potentiometer ....29
9.1 Description ..................29
9.2 Electrical installation .............30
10. CU 300 connected to water meter .....31
10.1 Description ..................31
10.2 Electrical installation .............32
11. Constant water level ............33
11.1 Description ..................33
11.2 Function ....................33
11.3 Electrical installation .............34
12. CU 300 connected to RS-485 ........36
12.1 Description ..................36
12.2 CU 300 connected to a PC directly......36
12.3 Electrical installation .............37
13. Alarm functions ...............39
13.1 No contact...................39
13.2 Overvoltage ..................39
13.3 Undervoltage .................40
13.4 Dry running ..................40
13.5 Speed reduction................41
13.6 Overtemperature ...............41
13.7 Overload ...................42
13.8 Sensor alarm .................42
14. CU 300 with Grundfos GO .........43
14.1 Menu overview ................44
15. Description of functions ..........46
15.1 Status .....................46
15.2 Settings ....................47
15.3 Alarms and warnings .............52
16. Technical data ................53
17. Disposing of the product ..........55
18. Document quality feedback ........55
4
English (GB)

1. General information
Read this document before you install the
product. Installation and operation must
comply with local regulations and accepted
codes of good practice.
This appliance can be used by children
aged from 8 years and above and persons
with reduced physical, sensory or mental
capabilities or lack of experience and
knowledge if they have been given
supervision or instruction concerning use
of the appliance in a safe way and
understand the hazards involved.
Children shall not play with the appliance.
Cleaning and user maintenance shall not
be made by children without supervision.
1.1 Hazard statements
The symbols and hazard statements below may
appear in Grundfos installation and operating
instructions, safety instructions and service
instructions.
DANGER
Indicates a hazardous situation which, if
not avoided, will result in death or serious
personal injury.
WARNING
Indicates a hazardous situation which, if
not avoided, could result in death or
serious personal injury.
CAUTION
Indicates a hazardous situation which, if
not avoided, could result in minor or
moderate personal injury.
The hazard statements are structured in the following
way:
SIGNAL WORD
Description of the hazard
Consequence of ignoring the warning
• Action to avoid the hazard.
1.2 Notes
The symbols and notes below may appear in
Grundfos installation and operating instructions,
safety instructions and service instructions.
Observe these instructions for explosion-
proof products.
A blue or grey circle with a white graphical
symbol indicates that an action must be
taken.
A red or grey circle with a diagonal bar,
possibly with a black graphical symbol,
indicates that an action must not be taken
or must be stopped.
If these instructions are not observed, it
may result in malfunction or damage to the
equipment.
Tips and advice that make the work easier.
5
English (GB)

2. General
The control unit CU 300 is developed for the SQE
submersible pumps.
CU 300 covers the voltage range 1 x 100-240 V - 10
%/+ 6 %, 50/60 Hz, PE.
CU 300 has the following functions:
• control of the pump on the basis of sensor signals
• setting of operating parameters
• monitoring of operation and alarm indication, if
any.
CU 300 indicates the following alarms:
• no contact
• overvoltage
• undervoltage
• dry running
• speed reduction
• overtemperature
• overload
• sensor alarm.
The individual alarms are described in details in
section 13. Alarm functions.
CU 300 receives alarm signals from the motor for the
following parameters:
• dry running
• incipient pump or motor defect
• too high temperature in motor electronics
• supply failure.
As standard, CU 300 incorporates an alarm signal
relay.
2.1 Expansion possibilities
CU 300 enables the use of the following devices:
•Grundfos GO:
Wireless infra-red remote control that enables
change of factory settings and monitoring of the
installation by calling up actual operating data,
e.g. speed, operating hours and power
consumption.
•External sensors:
Reception of data from external sensors and
control according to the data received, e.g. flow
rate, pressure, water level and conductivity.
•External potentiometer SPP 1:
Manual speed control.
Related information
15.2.8 External setpoint
2.2 On/Off button
By means of the On/Off button on CU 300, you can
do the following:
• Start or stop the pump.
• Reset alarms.
1
2
TM012829
Pos. Description
1 Green
2 Red
The green and red indicator lights in the On/Off button
indicate pump operating condition as follows:
Indication Description
Green indicator light
permanently on Pump is operating
Green indicator light
flashing
Pump has been stopped by
one of the following:
• a sensor
• an external on/off switch
• a stop command from the
Grundfos GO
Red indicator light
permanently on
Pump has been stopped by
means of the On/Off button *
Red indicator light
flashing
CU 300 is communicating
with the Grundfos GO
*If you use the On/Off button to stop the pump, you must also
use this button for restarting the pump.
If you press the On/Off button for minimum 5 seconds, you
start the pump, irrespective of any active fault or alarm
indications. When you release the On/Off button, the pump
will stop.
6
English (GB)

3. Mechanical installation
WARNING
Electric shock
Death or serious personal injury
‐Before starting any work on CU 300,
make sure that the power supply has
been switched off and that it cannot be
accidentally switched on.
3.1 Location
You can place CU 300 both indoors and outdoors.
The control unit must not be exposed to direct
sunlight.
3.2 Mounting CU 300
CU 300 is designed for wall mounting.
The box has six mounting holes (∅4). See fig.
Dimensions. The dimensions are in mm.
CU 300 must be mounted as follows:
• Horizontally to allow condensed water, if any, to
escape. See fig. Dimensions.
• On a plane surface to avoid deformation of the
box.
104.5
104.5
100
140.5
TM012824
Dimensions
CU 300 is supplied with a set of gaskets for the Pg
screwed connections.
The gaskets are to be used for the connection of
cables or wires to ensure tight connections, IP55, and
cable relief.
4. CU 300 as an alarm unit
4.1 Description
When CU 300 is connected to an SQE pump, one of
the eight red indicator lights on CU 300 will indicate
any alarm.
The indications are based on signals from the motor
and from sensors, if installed. The individual alarms
are described in details in section 13. Alarm
functions.
You can connect an external alarm-signal transmitter
and an external on/off switch. See section
4.2 Electrical installation concerning connection, etc.
Figure CU 300 as an alarm unit shows an example of
an installation with CU 300 as an alarm unit.
TM013150
CU 300 as an alarm unit
CU 300 functions as an alarm unit for the pump.
Furthermore, you can communicate with the pump via
the remote control Grundfos GO, see also section
14. CU 300 with Grundfos GO.
Related information
4.2 Electrical installation
14. CU 300 with Grundfos GO
7
English (GB)

4.2 Electrical installation
WARNING
Electric shock
Death or serious personal injury
‐Never make any connections in the CU 300 unit unless the power supply has been switched off.
CU 300 must be connected in accordance with the rules and standards in force for the application
in question.
The supply voltage and frequency are marked on the nameplate. Make sure that CU 300 is suitable for the
power supply on which it will be used.
K1
POWER
PE
PUMP
RELAY
ALARM
COM
NC NO
NO NC COM
AUX
RELAY IN
DI G
IN
+24VDC
GND GND
+24VDC
IN
SENSOR
1 2
SENSOR
IN
+24VDC
GND
RS
485
RS
232
B
GND
A
RI
DTR
RXD GND
5 6 7
1 2
1098
3 4
111213 161514 171819
PE
TXD
LNL N
HS1
TM013067
Electrical installation - CU 300 as alarm unit
Pos. Description
S1 On/off switch for start or stop of pump
H Alarm signal transmitter (optional)
K1 Internal alarm signal relay
Relay data: 250 VAC, 1 A, AC1
Related information
4.1 Description
4.2.1 Mains supply
POWER, terminals 1, 2 and PE
Connect terminals 1 and 2 to the phase and neutral
leads of the mains supply. You can connect each
terminal to any of the two leads.
Connect the PE terminal to the green/yellow earth
lead. You must connect each PE terminal to an earth
lead of its own.
The maximum cross-section of the leads to be
connected is 6 mm2.
Backup fuse: Maximum 16 A.
You must not connect the leads of the
mains supply to terminals 3 and 4.
8
English (GB)

4.2.2 Pump supply
PUMP, terminals 3, 4 and PE
Connect terminals 3 and 4 to the phase and neutral
leads of the pump. You can connect each terminal to
any of the two leads.
Connect the PE terminal to the green/yellow earth
lead. You must connect each PE terminal to an earth
lead of its own.
The maximum cross-section of the leads to be
connected is 6 mm2.
4.2.3 Alarm signal relay
ALARM RELAY, terminals 5, 6 and 7
Connect terminals 5, 6 and 7 to the internal alarm
signal relay as follows:
• Terminal 5 NC (normally closed).
• Terminal 6 COM (common).
• Terminal 7 NO (normally open).
The relay is activated when the alarm and warning
limits are exceeded.
You can select manual or automatic restarting in the
Grundfos GO display "Automatic restarting".
Manual restarting is carried out by means of the
On/Off button on CU 300.
4.2.4 Digital input
DIG IN, terminals 11, 12 and 13
In fig. Electrical installation - CU 300 as alarm unit,
the digital input is used to start and stop the pump.
You can select the function of the digital input by
means of the Grundfos GO in the display "Digital
input".
4.3 Description of dry-running protection
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 Grundfos GO display "Dry-
running stop", the pump will stop and CU 300 will
indicate the dry-running alarm.
Related information
15.2.20 Dry-running protection
4.3.1 Function
The dry-running protection applies only if the motor
speed lies within the maximum speed range (i.e.
maximum speed less than 1000 min-1). See fig. Pump
power input curve.
Normally, maximum speed is 10,700 min-1. However,
you can reduce the maximum speed in the Grundfos
GO display "Maximum speed". The dry-running power
limit set in the display "Dry-running stop" must match
the speed.
Changing the setpoint:
If you use the Grundfos GO display "Setpoint" or
"External setpoint" to change the setpoint, the pump
can be forced to run at a reduced speed in relation to
the maximum speed. The dry-running protection will
not protect the pump if the reduced speed lies outside
the maximum speed range (i.e. maximum speed less
1000 min-1). See fig. Pump power input curve.
Constant-pressure control
In constant-pressure control mode, the dry-running
protection is active, as the motor will operate at
maximum speed in connection with dry running.
Pump power input curve
The curve shows the pump power input in relation to
the pump speed.
12345
8
7
6
TM012689
Pump power input curve
Pos. Description
13000 min-1
2Max. speed -1000 min-1
3Max. speed as set in section Maximum
speed
410,700 min-1
5 Motor speed
6 Pump power input [Watt]
7 Pump power curve
8 Dry-running power limit set
Related information
15.2.22 Maximum speed
15.2.3 Setpoint
9
English (GB)

4.4 Settings
For a detailed description of the Grundfos GO
displays, see section 14. CU 300 with Grundfos GO.
4.4.1 Required Grundfos GO settings
If the maximum speed of the pump has been reduced
by more than 1000 min-1, 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 stop. See fig.
Pump power input curve.
Set the dry-running power limit in the display Dry-
running stop by following the procedure below:
• Start the pump against a closed discharge pipe.
• Read the input power (P1) in the display Power
consumption.
• Calculate the dry-running power limit: P1 x 0.9
[W].
• Set this value in the display Dry-running stop.
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 15.2.21 Dry-running
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.
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 Dewatering,
maximum "On" and "Off" time.
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" time.
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 Power
consumption.
3. Calculate the dry-running power limit: P1 x 0.9
[W].
4. Set this value in the display Dry-running stop.
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
10
English (GB)

4.5.4 On/off times
The dewatering function means that there is a
dependence between the period of time during which
the pump is running, the on time, and the period of
time during which the pump is stopped, the off time.
Figure On and off times shows an example of on and
off times set in the display Dewatering, maximum
"On" and "Off" time.
35
1
125 60
60
A
B
TM063501
On and off times
Pos. Description
A Off time [minutes]
B On time [minutes]
Explanation:
The on and off times are set to 60 minutes each. The
pump has been running for 25 minutes when dry
running occurs. The pump will be stopped for 35
minutes. If the pump has been running for e.g. 120
minutes, the stop time will be 1 minute.
Related information
15.2.19 Dewatering, maximum "On" and "Off" time
11
English (GB)

5. CU 300 with constant-pressure
control - 0 to 6 bar
5.1 Description
Using constant-pressure control enables automatic
adjustment of the pump performance according to
consumption. The system maintains a constant
pressure within the maximum pump performance in
spite of a varying water consumption.
Figure Constant-pressure control - from 0 to 6 bar
shows an example of an installation with constant-
pressure control within the range from 0 to 6 bar.
1
2
3
TM019649
Constant-pressure control - from 0 to 6 bar
Pos. Description
1 CU 300
2Diaphragm tank
Absorbs pressure variations.
3
Pressure sensor
The required pressure is set using the
Grundfos GO.
5.2 Function
The pressure is registered by means of the pressure
sensor, which transmits a signal to CU 300. CU 300
adjusts the pump performance accordingly by
changing the pump speed.
Mains borne signalling
The communication between CU 300 and the pump is
effected via the power supply cable.
This communication principle is called mains borne
signalling or power line communication. Using this
principle means that no additional cables to the pump
are required.
The communication of data is effected by means of a
high-frequency signal transmitted to the power supply
cable and led into the electronics unit by means of
signal coils incorporated in the motor and CU 300
respectively.
When does the pump start?
The pump starts as a consequence of:
• high flow
• low pressure
• a combination of both.
To ensure that the pump is started when water is
consumed, a flow detection is required. The flow is
detected via pressure changes in the system. When
water is consumed, the pressure will drop accordingly
depending on the size of the diaphragm tank and the
water flow:
• At a low flow, the pressure will drop slowly.
• At a high flow, the pressure will drop quickly.
2
4
1
3
TM018545
Pos. Description
1 Pressure
2 Low flow
3 Time
4 High flow
When the pressure is dropping 0.1 bar/s or
faster, the pump will start immediately.
If you use a diaphragm tank of 8 litres, the pump will
start at a flow rate of approx. 0.18 m3/h.
If a you use a larger tank, the flow must be
higher before the pump starts.
Consumption up to 0.18 m3/h
The pump will start when the pressure has dropped to
0.5 bar below the pressure setting.
The pump will run until the pressure is 0.5 bar above
the pressure set.
12
English (GB)

Flow detection
During pump operation, i.e. when water is consumed,
CU 300 will adjust the pump speed to maintain a
constant pressure. In order to stop the pump when no
water is consumed, CU 300 performs flow detection
every 10 seconds.
The pump speed is reduced until a small pressure
drop is registered. This pressure drop indicates that
water is consumed and the pump speed is resumed.
See fig. Flow detection every 10 seconds during
operation.
If the pump speed can be reduced without any
pressure drop being registered, this indicates that no
water is consumed. The diaphragm tank will be filled
with water and the pump will be stopped.
1
10 s 10 s
2
3
TM018546
Flow detection every 10 seconds during operation
Pos. Description
1 Flow detection
2 Pressure
3 Time
System limits
Even though CU 300 is controlling the pressure within
± 0.2 bar, bigger pressure variations may occur in the
system.
If the consumption is suddenly changed, e.g. if a tap
is opened, the water must start flowing before the
pressure can be made constant again. Such dynamic
variations depend on the pipework, but, typically, they
will lie between 0.5 and 1 bar.
If the desired consumption is higher than the quantity
the pump is able to deliver at the desired pressure,
the pressure follows the pump curve as illustrated in
fig. Possible pressure variations during constant-
pressure operation.
2
1
A
345
6
8
7
TM018634
Possible pressure variations during constant-
pressure operation
Pos. Description
1 Stop
2 Pressure
3 Start
4 Controlling
5 Dynamic variation
6 Flow
7 0.18
8m3/h
A Required pressure
13
English (GB)

5.3 Positioning the pressure sensor
Pressure loss often causes inconvenience to the
user. CU 300 keeps the pressure constant in the
place where the pressure sensor is positioned.
4
3
12
TM019670
Pressure sensor position
Pos. Description
1 Tap 1
2 Tap 2
3 8 l
4 CU 300
In fig.Pressure sensor position, tap 1 is placed close
to the pressure sensor. Therefore, the pressure will
be kept nearly constant at tap 1, as the friction loss is
small. At the shower and tap 2, the friction loss is
bigger. This, of course, depends on the piping.
However, old and furred-up piping may cause
inconvenience due to friction loss.
Therefore, we recommend that you position the
pressure sensor as close to the places of
consumption as possible.
5.4 System sizing
WARNING
Death or serious personal injury
‐The installation must be designed for
the maximum pump pressure.
In normal installations with CU 300 and an SQE
pump set to constant-pressure control, the required
tank size is 8 litres. You can use bigger tanks without
causing any problems.
14
English (GB)

5.5 Electrical installation
WARNING
Electric shock
Death or serious personal injury
‐Never make any connections in the CU 300 unit unless the power supply has been switched off.
CU 300 must be connected in accordance with the rules and standards in force for the application
in question.
The supply voltage and frequency are marked on the nameplate. Make sure that CU 300 is suitable for the
power supply on which it will be used.
K1
POWER
PE
PUMP
RELAY
ALARM
COM
NC NO
NO NC COM
AUX
RELAY IN
DI G
IN
+24VDC
GND GND
+24VDC
IN
SENSOR
1 2
SENSOR
IN
+24VDC
GND
RS
485
RS
232
B
GND
A
RI
DTR
RXD
GND
1098 111213 161514 171819
PE
TXD
LNL N
H
1
3
2
4
1 2 3 4
56 7
TM019650
Pos. Description
1 Pressure sensor, brown lead, terminal 14
2 Pressure sensor, black lead, terminal 15
3 Pressure sensor, screen, terminal GND
4Pressure sensor
Must be connected to analog input 1.
H Alarm signal transmitter (optional).
K1 Internal alarm signal relay
Relay data: 250 VAC, 1 A, AC1
15
English (GB)

5.5.1 Mains supply
POWER, terminals 1, 2 and PE
Connect terminals 1 and 2 to the phase and neutral
leads of the mains supply. You can connect each
terminal to any of the two leads.
Connect the PE terminal to the green/yellow earth
lead. You must connect each PE terminal to an earth
lead of its own.
Maximum cross-section of the leads to be connected
is 6 mm2.
Backup fuse: Maximum 16 A.
You must not connect the leads of the
mains supply to terminals 3 and 4.
5.5.2 Pump supply
PUMP, terminals 3, 4 and PE
Connect terminals 3 and 4 to the phase and neutral
leads of the pump. You can connect each terminal to
any of the two leads.
Connect the PE terminal to the green/yellow earth
lead. You must connect each PE terminal to an earth
lead of its own.
Maximum cross-section of the leads to be connected
is 6 mm2.
5.5.3 Alarm signal relay
ALARM RELAY, terminals 5, 6 and 7
Connect terminals 5, 6 and 7 to the internal alarm
signal relay as follows:
• Terminal 5 NC (normally closed).
• Terminal 6 COM (common).
• Terminal 7 NO (normally open).
The relay operates when the alarm and warning limits
are exceeded.
You can select manual or automatic restarting in the
Grundfos GO display "Automatic restarting".
Manual restarting is carried out by means of the
On/Off button on CU 300.
5.5.4 Required Grundfos GO settings
You must make the following Grundfos GO settings:
1. In display "Control mode" select "Closed loop".
2. Set the sensor in the "Analog input 1" or "Analog
input 2" display.
Example:
• sensor output signal (4-20 mA)
• setting range unit (m)
• setting range - head
- min.: 0.0
- max.: 40
3. Set the stop type in the "Stop type, sensor 1"
display.
• "Fill".
4. Set the digital input.
• "Not active"
5. Set the setpoint
Example: Desired head 35 m.
Rule: The maximum setting of the setpoint
corresponds to the maximum value set in display
Analog inputs less 5 m.
In this case, 40 less 5 = 35 m.
Related information
15.2.4 Analog inputs
5.6 Startup
Prior to startup, the precharge pressure of the
diaphragm tank must be set to 70 % of the setpoint
set in the Grundfos GO display "Setpoint".
16
English (GB)

6. CU 300 with constant-pressure
control - 0 to 10 bar
6.1 Description
Using constant-pressure control enables automatic
adjustment of the pump performance according to
consumption. The system maintains a constant
pressure within the maximum pump performance in
spite of a varying water consumption.
Figure Constant-pressure control - from 0 to 10 bar
shows an example of an installation with constant-
pressure control within the range from 0 to 10 bar.
1
2
3
4
TM012653
Constant-pressure control - from 0 to 10 bar
Pos. Description
1 CU 300
2Diaphragm tank
Absorbs pressure variations.
3
Flow switch
The pump starts at once when water is
consumed at the taps.
4
Pressure sensor
The required pressure is set using the
Grundfos GO.
6.2 Function
The pressure is registered by means of the pressure
sensor and transmitted to CU 300. CU 300 adjusts
the pump performance accordingly. To ensure that the
pump is started when water is consumed, include a
flow switch in the system.
The required pressure (setpoint) is set in the
Grundfos GO display "Setpoint".
•Consumption up to 0.18 m3/h.
The flow switch contact is open.
The pump starts when the pressure is equal to the
setpoint less 0.5 bar. The pump will fill the tank
and stop when the pressure is equal to the
setpoint plus 0.5 bar. Consequently, the pump
runs on/off operation.
•Consumption above 0.18 m3/h.
The flow switch contact is closed.
The pump starts when the flow switch contact
closes and the speed control ensures that the
pressure is kept constant. If the flow is below 0.18
m3/h and the flow switch contact is opened, the
tank is filled to a pressure equal to the setpoint
plus 0.5 bar. When this pressure is reached, the
pump stops. Stopping is a combination of the flow
switch contact opening and the pressure being
equal to the setpoint plus 0.5 bar.
If the flow is larger than the quantity the pump is able
to deliver at the desired pressure, the pressure
follows the pump curve as illustrated in fig. Possible
pressure variations during constant-pressure
operation.
2
1
A
345
6
8
7
TM018634
Possible pressure variations during constant-
pressure operation
Pos. Description
1 Stop (+ 0.5 bar)
2 Pressure
3Start
(- 0.5 bar)
4 Controlling (± 0.2 bar)
5 Dynamic (± 0.5 bar)
6 Flow
7 0.18
8m3/h
A Required pressure
17
English (GB)

6.3 Positioning the pressure sensor
Pressure loss often causes inconvenience to the
user. CU 300 keeps the pressure constant in the
place where the pressure sensor is positioned.
3
4
12
TM012834
Pressure sensor position
Pos. Description
1 Tap 1
2 Tap 2
3 CU 300
4 8 l
In fig. Pressure sensor position, tap 1 is placed close
to the pressure sensor. Therefore, the pressure will
be kept nearly constant at tap 1, as the friction loss is
small. At the shower and tap 2, the friction loss is
bigger. This, of course, depends on the piping.
However, old and furred-up piping may cause
inconvenience due to friction loss.
Therefore, we recommend that you position the
pressure sensor as close to the places of
consumption as possible.
6.4 System sizing
WARNING
Death or serious personal injury
‐The installation must be designed for
the maximum pump pressure.
In normal installations with CU 300 and an SQE
pump set to constant-pressure control, the required
tank size is 8 litres. You can use bigger tanks without
causing any problems.
18
English (GB)

6.5 Electrical installation
WARNING
Electric shock
Death or serious personal injury
‐Never make any connections in the CU 300 unit unless the power supply has been switched off.
CU 300 must be connected in accordance with the rules and standards in force for the application
in question.
The supply voltage and frequency are marked on the nameplate. Make sure that CU 300 is suitable for the
power supply on which it will be used.
56
4
K1
POWE R
PE
PUMP
RELAY
ALARM
COM
NC NO
NO
NC
COM
AUX
RELAY IN
DI G
IN
+24VDC
GND GND
+24VDC
IN
SENSOR
1 2
SENSOR
IN
+24VDC
GND
RS
485
RS
232
B
GND
A
RI
DTR
RXD
GND
7
1098 111213 161514 171819
PE
TXD
LNL N
H1
3
2
1234
56
TM013089
Pos. Description
1 Pressure sensor, brown lead, terminal 14
2 Pressure sensor, black lead, terminal 15
3 Pressure sensor, screen, terminal GND
4Pressure sensor
Must be connected to analog input 1.
5 Diaphragm tank connection
6
Flow switch
Must be connected to the digital input,
terminals 12 and 13. Cannot be connected
wrongly.
H Alarm signal transmitter (optional)
K1 Internal alarm signal relay
Relay data: 250 VAC, 1 A, AC1
19
English (GB)

6.5.1 Mains supply
POWER, terminals 1, 2 and PE
Connect terminals 1 and 2 to the phase and neutral
leads of the mains supply. You can connect each
terminal to any of the two leads.
Connect the PE terminal to the green/yellow earth
lead. You must connect each PE terminal to an earth
lead of its own.
Maximum cross-section of the leads to be connected
is 6 mm2.
Backup fuse: Maximum 16 A.
You must not connect the leads of the
mains supply to terminals 3 and 4.
6.5.2 Pump supply
PUMP, terminals 3, 4 and PE
Connect terminals 3 and 4 to the phase and neutral
leads of the pump. You can connect each terminal to
any of the two leads.
Connect the PE terminal to the green/yellow earth
lead. You must connect each PE terminal to an earth
lead of its own.
Maximum cross-section of the leads to be connected
is 6 mm2.
6.5.3 Alarm signal relay
ALARM RELAY, terminals 5, 6 and 7
Connect terminals 5, 6 and 7 to the internal alarm
signal relay as follows:
• Terminal 5 NC (normally closed).
• Terminal 6 COM (common).
• Terminal 7 NO (normally open).
The relay operates when the alarm and warning limits
are exceeded.
You can select manual or automatic restarting in the
Grundfos GO display "Automatic restarting".
Manual restarting is carried out by means of the
On/Off button on CU 300.
6.5.4 Required Grundfos GO settings
You must make the following Grundfos GO settings:
1. In display Control mode" select "Closed loop".
2. Set the sensor in the "Analog input 1" or "Analog
input 2" display.
Example:
• sensor output signal (4-20 mA)
• setting range unit (m)
• setting range - head
- min.: 0.0
- max.: 40.
3. Set the stop type in the "Stop type, sensor 1"
display.
• "Fill".
4. Set the digital input.
• "Not active"
5. Set the setpoint
Example: Desired head 35 m.
Rule: The maximum setting of the setpoint
corresponds to the maximum value set in display
"Analog input 1" less 5 m.
In this case, 40 less 5 = 35 m.
Related information
15.2.2 Control mode
6.6 Startup
Prior to startup, the precharge pressure of the
diaphragm tank must be set to 70 % of the setpoint
set in the Grundfos GO display "Setpoint".
20
English (GB)