Grundfos CU 301 User guide

CU 301
GRUNDFOS INSTRUCTIONS
Installer’s manual

2
CONTENTS
Page
1. Constant-pressure control 3
1.1 Description 3
1.2 Function 3
1.3 System sizing 5
1.4 Positioning the pressure sensor 6
1.5 Precharge pressure setting 6
1.6 Pressure relief valve 6
2. Operating functions 7
2.1 On/off button 7
2.2 Indication of pump operation 7
2.3 Pressure setting 7
2.4 Button locking 8
3. Alarm functions 8
3.1 Service alarm 8
3.2 Dry-running protection 9
4. Position of LEDs and fuse 10
5. CU 301 with R100 11
5.1 Menu OPERATION 14
5.1.1 Pressure setting 14
5.1.2 Operating mode 14
5.1.3 Alarm 14
5.2 Menu STATUS 15
5.2.1 Operating mode 15
5.2.2 Actual pressure 15
5.2.3 Speed 15
5.2.4 Temperature 15
5.2.5 Power input and power consumption 15
5.2.6 Operating hours and number of starts 16
5.3 Menu INSTALLATION 16
5.3.1 Sensor 16
5.3.2 Choice of sensor 16
5.3.3 Maximum pressure setting 16
5.3.4 Automatic restart 17
5.3.5 Dry-running stop 17
5.3.6 Maximum speed 17
5.3.7 Buttons on CU 301 17
5.3.8 Indication of pump operation 18
5.3.9 Number 18
6. Fault finding 19
6.1 Service 19
7. Technical data 23
7.1 Electrical connection 24
7.1.1 Mains supply 25
7.1.2 Pump supply 25
7.1.3 Pressure sensor 25

3
1. Constant-pressure control
1.1 Description
The system maintains a constant pressure within the
maximum pump performance in spite of a varying
water consumption.
Fig. 1 shows an example of an installation with con-
stant-pressure control.
Fig. 1
1.2 Function
The pressure is registered by means of the pressure
sensor, which transmits a signal to the CU 301. The
CU 301 adjusts the pump performance accordingly
by changing the pump speed.
Mains borne signalling:
The communication between the CU 301 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 sup-
ply cable and led into the electronics unit by means
of signal coils incorporated in the motor and the
CU 301 respectively.
Fig. 2 shows the principle of mains borne signalling
between the CU 301 and the pump.
Fig. 2
TM01 7862 4999
Pos. Description
1 CU 301
2 Diaphragm tank
3 Pressure sensor
4 SQE pump
1
4
23
TM01 8495 1703
Pos. Description
1 Supply to the electronics
2 Signal coils
3 Capacitor
4Electronics for the control of the com-
munication
5 On/off button
6 Sensor signal
7 Electricity supply
8 Communication signals
R 100
CU 301
15
24
3
6
78

4
When does the pump start?
The pump starts as a consequence of...
• a high flow or
• a low pressure or
• 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 according-
ly 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.
See fig. 3.
Fig. 3
Note: When the pressure is dropping 0.1 bar/s or
faster, the pump will start immediately.
If a diaphragm tank of 8 litres is used, the pump will
start at a flow rate of approx. 0.18 m³/h.
Note: If a larger tank is used, 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.
Flow detection:
During pump operation, i.e. when water is con-
sumed, the CU 301 will adjust the pump speed to
maintain a constant pressure. In order to stop the
pump when no water is consumed, the CU 301 per-
forms 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. 4.
If the pump speed can be reduced without any pres-
sure drop being registered, this indicates that no
water is consumed. The diaphragm tank will be filled
with water and the pump will be stopped.
Fig. 4
System limits:
Even though the CU 301 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 pipe-
work, 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. 5.
Fig. 5
A = Pressure set
TM01 8545 0400
Pressure
Time
Low flow
High flow
TM01 8546 0400TM01 8634 0500
Pressure
Time
Flow detection
10 s10 s
Controlling
±0.2 bar Dynamic
variations
±0.5 bar
Pressure
Start
-0.5 bar
A
Stop
+0.5 bar
m³/h
0.18
F
low
Flow

5
1.3 System sizing
To ensure the correct function of the system, it is
important that the pump is of the right type.
During operation, the CU 301 controls the pump
speed within the range from 3,000 min-1 to 10,700
min-1, see fig. 6.
It is recommended to follow the guidelines below:
Fig. 6
The following must be fulfilled:
1. Min. head at no flow < static head + system pres-
sure.
2. Max. head at max. flow > dynamic head + system
pressure.
Max. head at max. flow and min. head at no flow can
be found in the following table:
TM01 8547 0400
H [m]
Q [m³/h]
Max. head at max. flow
Min. head at no flow
Pump curve
at 10,700 min-1
Pump curve
at 3,000 min-1
Qmax
Pump type
Min. head
at Q = 0 m³/h,
3,000 min-1
Max. head
at Q = Qmax,
10,700 min-1
[m] / [feet] [m] / [feet]
SQE 1 - 35 18 / 59 29 / 86
SQE 1 - 50 28 / 91 44 / 131
SQE 1 - 65 37 / 121 59 / 177
SQE 1 - 80 46 / 151 75 / 222
SQE 1 - 95 56 / 184 90 / 270
SQE 1 - 110 65 / 213 105 / 315
SQE 1 - 125 74 / 243 120 / 360
SQE 1 - 140 81 / 266 136 / 405
SQE 1 - 155 92 / 302 151 / 450
SQE 2 - 35 19 / 62 35 / 105
SQE 2 - 55 29 / 95 54 / 164
SQE 2 - 70 38 / 125 71 / 215
SQE 2 - 85 47 / 154 88 / 267
SQE 2 - 100 56 / 184 108 / 328
SQE 2 - 115 66 / 217 128 / 390
SQE 3 - 30 15 / 49 26 / 75
SQE 3 - 40 24 / 79 42 / 123
SQE 3 - 55 31 / 102 56 / 164
SQE 3 - 65 39 / 128 70 / 205
SQE 3 - 80 47 / 154 84 / 246
SQE 3 - 95 55 / 180 98 / 287
SQE 3 - 105 62 / 203 113 / 328
SQE 5 - 15 7.7 / 25 11 / 36
SQE 5 - 25 15 / 49 23 / 77
SQE 5 - 35 23 / 75 36 / 117
SQE 5 - 50 30 / 98 48 / 159
SQE 5 - 60 38 / 125 61 / 200
SQE 5 - 70 45 / 148 73 / 240
SQE 7 - 15 8.6 / 28 9 / 33
SQE 7 - 30 18 / 59 23 / 82
SQE 7 - 40 27 / 89 37 / 126

6
1.4 Positioning the pressure sensor
Pressure losses often cause inconvenience to the
user. The CU 301 keeps the pressure constant in the
place where the pressure sensor is positioned, see
fig. 7.
Fig. 7
In fig. 7, 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.
Example: A person is in the shower. Tap 2 is
opened. The increased flow will cause pressure loss
in the pipe, and even though the CU 301 is keeping
the pressure constant at the pressure sensor, the
person in the shower will feel the pressure loss.
If the pressure sensor is placed closer to the shower
tap, the CU 301 will increase the pressure when the
flow is increased. Then the pressure at the shower
and tap 2 will be kept constant, but the pressure at
tap 1 will be increased.
Therefore, it is recommended that the pressure sen-
sor be positioned as close to the places of consump-
tion as possible.
1.5 Precharge pressure setting
The precharge pressure of the diaphragm tank must
be set to 70% of the pressure setting in order to use
the tank to the limit of its capacity. This is of course
especially important when the tank volume is limited
to 8 litres.
Use the values in the following table:
Note: If the precharge pressure is higher than the
pressure setting, the system will not be able to con-
trol the pressure.
If the user wants to adjust the pressure without
changing the precharge pressure of the diaphragm
tank, the precharge pressure must be equal to the
lowest pressure setting used. This means that the
control will work but that the pressure fluctuations
might increase. In such cases, it is recommended to
use a larger diaphragm tank, e.g. a tank of double
size.
1.6 Pressure relief valve
In order to provide protection against the possibility
of an overpressurization, a pressure relieve valve
should be installed down stream of the well head.
The setpoint of the pressure relief valve should be at
least 30 psi above the pressure setting, see section
2.3.
If a relief valve is installed, it is recommended that its
discharge be plumbed into an appropriate drainage
point.
TM01 7862 4999
Setting [bar] Precharge pressure [bar]
21.4
2.5 1.8
32.1
3.5 2.5
42.8
4.5 3.2
53.5
Tap 1 Tap 2

7
2. Operating functions
2.1 On/off button
Fig. 8 shows the on/off button of the CU 301.
Fig. 8
The green and red indicator lights in the on/off button
indicate pump operating condition as follows:
* If the on/off button has been used to stop the
pump, this button must also be used for restarting.
Any alarm indication can be reset by pressing the
on/off button.
If the on/off button is pressed for more than 5 sec-
onds, the pump is started, irrespective of any active
fault/alarm indications and sensor signals.
When the on/off button is released, the pump will
stop, if the alarm still exists.
2.2 Indication of pump operation
On the graphical illustration on the CU 301 front, the
riser pipe shows running light when the pump is
operating. When the pump is not operating, none of
the indicator lights are on, see fig. 9.
Fig. 9
The indication of pump operation can be changed by
means of the R100.
Possible settings:
• “Running light” during pump operation (factory
setting).
• “Constant light” during pump operation.
2.3 Pressure setting
The two arrow buttons on the CU 301 front are used
for the pressure setting, see fig. 10.
Fig. 10
TM01 7860 4701
Indication Description
Greenindicatorlight
permanently on. The system is operational.
Greenindicatorlight
off. The system is not opera- tional.
Red indicator light
permanently on. Pump has been stopped by means of the on/off button.*
Red indicator light
flashing. The CU 301 is communicat- ing with the R100.
Zielona dioda
Czerwona dioda
bar
5.0
4.5
4.0
3.5
3.0
2.5
2.0
Green indi
-
cator light
Red indicator
light
TM01 8328 4701TM01 8329 4701
bar
5.0
4.5
4.0
3.5
3.0
2.5
2.0
bar
5.0
4.5
4.0
3.5
3.0
2.5
2.0
bar
5.0
4.5
4.0
3.5
3.0
2.5
2.0

8
Indication of pressure setting:
The system pressure set is indicated by a yellow
indicator light, which is permanently on.
Setting range: 2, 2.5 ... 5.0 bar.
Arrow-up button:
When this button is pressed, the system pressure
setting is increased in steps of 0.5 bar.
Arrow-down button:
When this button is pressed, the system pressure
setting is decreased in steps of 0.5 bar.
2.4 Button locking
The buttons on the CU 301 can be locked/unlocked
by pressing the two arrow buttons simultaneously for
5 seconds or via the R100 remote control.
Note: When the arrow buttons are used for locking,
the pressure setting may change.
Use the following procedure:
1. Set the pressure one step up.
2. Press the arrow-down button as the first one
when pressing the two buttons.
Fig. 11
When the buttons are locked, the indicator light is
permanently on, see fig. 11.
For further information, see section 5.3.7 Buttons on
CU 301.
3. Alarm functions
The CU 301 continuously receives operating data
from the pump. The alarm functions indicated on the
CU 301 front are described in the following sections.
3.1 Service alarm
If one or more factory-set alarm values are exceed-
ed, the indicator light for service alarm is permanent-
ly on, see fig. 12.
Fig. 12
Possible alarms:
• Sensor defective.
• Overload.
• Overtemperature.
• Speed reduction.
• Voltage alarm.
• No contact to pump.
The possible alarms and how to identify them and
make the relevant corrections are described in sec-
tion 6.1 Service.
TM01 8330 4701
bar
5.0
4.5
4.0
3.5
3.0
2.5
2.0
TM01 8327 4701
bar
5.0
4.5
4.0
3.5
3.0
2.5
2.0

9
3.2 Dry-running protection
The purpose of the dry-running protection is to pro-
tect the pump in case of insufficient water flow.
The dry-running protection makes the conventional
dry-running protection unnecessary.
No additional cables to the motor are required.
The dry-running protection will be active after
30 seconds’ operation.
The dry-running alarm is activated when the load has
been below the minimum power limit for an accumu-
lated time of 5 seconds.
The motor is stopped and the dry-running indicator
light is permanently on, see fig. 13, pos. A.
Fig. 13
Restarting:
After 5 minutes (factory setting), or the period set by
means of the R100 display 5.3.4 Automatic restart,
the motor will restart automatically.
TM01 8329 4701
Possible cause Remedy
Thepumpperformance
is too high compared to
the borehole yield.
Replace the pump with
a smaller one.
Reduce pump perform-
ance using the R100
display 5.3.6 Maxi-
mum speed.
Borehole filter is
blocked. Borehole service is re- quired.
bar
5.0
4.5
4.0
3.5
3.0
2.5
2.0
A

10
4. Position of LEDs and fuse
Fig. 14
TM01 8537 1703
1
2
3
4
5
Pos. Indication Description
1 +24 V overload Permanent red light when the internal 24 VDC supply is overloaded.
2 +24 V Permanent green light when the internal 24 VDC supply is OK.
3 +10 V Permanent green light when the internal 10 VDC supply is OK.
4 +5 V Permanent green light when the internal 5 VDC supply is OK.
5 9 indicator lights:
• Control indicator • Flashing green light when the pump control is working correctly.
• Min. speed • Permanent yellow light when the pump is running at minimum speed,
3,000 min-1.
• Max. speed • Permanent yellow light when the pump is running at maximum
speed, 10,700 min-1.
• Sensor defective *) • Permanent red light when the sensor signal is out of signal range.
• Overload *) • Permanent red light when the motor load exceeds the stop limit, see
section 7. Technical data.
• Overtemperature *) • Permanent red light when the motor temperature exceeds the stop
limit, see section 7. Technical data.
• Speed reduction *) • Permanent red light when the pump speed is reduced, see section
7. Technical data.
• Voltage alarm *) • Permanent red light when the supply voltage is out of range, see
section 7. Technical data.
• No contact to pump *) • Permanent red light when communication between the CU 301 and
the pump is impossible.
*) Press the on/off button to reset the alarm indication.

11
5. CU 301 with R100
The remote control R100 can be used as a supple-
ment for the installer. The R100 is used for wireless
communication with the CU 301.
Note: It is not necessary to use the R100 to operate
the system. The R100 offers additional features.
The R100 communicates via infra-red light. During
communication, there must be visual contact be-
tween the CU 301 and the R100. The best visual
contact between the two units is obtained by pointing
the R100 at the lower arrow button or by removing
the front cover and pointing the R100 at the right
side of the CU 301, see fig. 15.
Fig. 15
The R100 offers possibilities of setting and status
displays for the CU 301.
When the communication between the R100 and
CU 301 has been established, the red indicator light
in the on/off button will flash.
For general use of the R100, see the operating in-
structions for this unit.
The menu structure for the R100 and CU 301 is
divided into four parallel menus, each including a
number of displays.
0. GENERAL, see operating instructions for the
R100.
1. OPERATION
2. STATUS
3. INSTALLATION
Menu overview, see fig. 16, page 12.
Note: The number stated at each individual display
in fig. 16 refers to the section in which the display is
described.
TM01 7861 4701
R100

12
Fig. 16
0.
GENERAL
2.
STATUS
3.
INSTALLATION
1.
OPERATION
5.1.1
5.1.2 5.1.3
5.2.1
5.2.2
5.2.3 5.2.4 5.2.5
5.3.2
5.3.1 5.3.3 5.3.4 5.3.5

13
5.3.9 5.3.8 5.3.7 5.3.6
5.2.6

14
5.1 Menu OPERATION
The OPERATION menu for the CU 301 offers the
possibility of setting and reading operating parame-
ters.
Factory settings are marked in bold-faced type
under each individual display.
5.1.1 Pressure setting
Set the required pressure.
Setting range:
•2.0-5.0 bar (0.5 bar intervals), 3.0 bar.
•40-100 psi (10 psi intervals), 50 psi.
Relation to other displays:
The setting in display 5.1.1 Pressure setting is over-
ridden by the “Max.” and “Min.” settings in the dis-
plays 5.1.2 Operating mode and 5.3.3 Maximum
pressure setting.
5.1.2 Operating mode
Select one of the following operating modes:
•Max.
Pump operation is set to maximum speed, irre-
spective of the pressure setting. The maximum
speed is set in display 5.3.6 Maximum speed
(factory setting: 10,700 min-1).
•Normal.
Normal operating mode, i.e. pump operation is
based on the pressure set in display 5.1.1 Pres-
sure setting.
•Min.
Pump operation is set to minimum speed,
3,000 min-1, irrespective of the pressure setting.
•Stop.
The pump is stopped.
If the on/off button has been used to stop the pump,
this button must also be used for restarting.
Relation to other displays:
The “Max.” and “Min.” settings override the pressure
setting in display 5.1.1 Pressure setting.
5.1.3 Alarm
This display shows the types of alarm that may
occur.
Possible alarms are described in the following table:
TM CU301_1_01 GBTM CU301_1_02 GB
TM CU301_1_03 GB
Alarm
indication Description
No fault indica-
tion No alarms are registered by the CU 301.
No contact to
pump No communication between the CU 301 and the pump.
Overvoltage The supply voltage exceeds
the limit value.
Undervoltage The supply voltage is below the
limit value.
Dry running The dry-running protection of
the pump has been activated.
Overtempera-
ture The motor temperature ex- ceeds the limit value.
Overload The current consumption of the
motor exceeds the limit value.
Sensor
defective
The sensor signal has fallen
outside the measuring range
set. The sensor signal of a
4-20 mA or 2-10 V sensor is
below 2 mA or 1 V respectively.

15
5.2 Menu STATUS
The STATUS menu for the CU 301 provides operat-
ing data about pump/motor and sensor. It is not pos-
sible to change or set values in this menu.
When [OK] is pressed continuously in this display,
the displayed value is being updated.
The measuring accuracy is stated in section 7. Tech-
nical data.
5.2.1 Operating mode
Possible operating modes:
•Max.
Pump operation has been set to maximum speed,
e.g. 10,700 min-1.
•Normal.
Normal operating mode, i.e. pump operation is
based on the pressure setting made in display
5.1.1 Pressure setting.
•Min.
Pump operation has been set to minimum speed,
3,000 min-1.
•Stop.
The pump has stopped.
The operating mode was selected from one of the
following:
•CU 301 (on/off button on the CU 301).
•R100.
•Sensor (signals received via the sensor input).
5.2.2 Actual pressure
The actual system pressure measured by the pres-
sure sensor.
Tolerance: ±1%.
5.2.3 Speed
The actual speed stated in min-1 (rpm).
Tolerance: ±1%.
5.2.4 Temperature
The actual temperature of the motor electronics
stated in “°C” or “F”.
Tolerance: ±5%.
Relation to other displays:
To select “F”, choose the language “US English”.
5.2.5 Power input and power consumption
Power input:
The actual motor power from the electricity supply.
The power input is displayed in W (watt).
Note: This value is used for the calculation of mini-
mum power limit (dry-running stop).
Power consumption:
The accumulated motor power consumption in kWh.
The value of power consumption is accumulated
from the pump’s birth and it cannot be reset.
The value
• is stored in the motor electronics, and it is kept
even if the CU 301 is replaced.
• is updated in the software every 2 minutes of con-
tinuous operation. The displayed value is updated
every two hours.
Tolerance: ±5%.
TM CU301_2_01 GBTM CU301_2_02 GB
TM CU301_2_03 GBTM CU301_2_04 GBTM CU301_2_05 GB

16
5.2.6 Operating hours and number of
starts
Operating hours:
The value of operating hours is accumulated from
the pump’s birth and it cannot be reset.
The value
• is stored in the motor electronics, and it is kept
even if the CU 301 is replaced.
• is updated in the software every 2 minutes of con-
tinuous operation. The displayed value is updated
every two hours.
Number of starts:
The value of number of starts is accumulated from
the pump’s birth and it cannot be reset.
The value is stored in the motor electronics, and it is
kept even if the CU 301 is replaced.
5.3 Menu INSTALLATION
The INSTALLATION menu for the CU 301 offers the
possibility of configuring the CU 301, pump/motor
and sensor.
Factory settings are marked in bold-faced type
under each individual display.
5.3.1 Sensor
Make the following settings according to sensor type:
• Sensor output signal: “–” (not active), 0-20 mA,
4-20 mA, 0-10 V, 2-10 V.
• Setting range unit: bar,psi.
Setting range, bar:
• Minimum value: 0.
• Maximum value: 2-6 (2, 2.5, 3, 3.5 ... 6.0).
Setting range, psi:
• Minimum value: 0.
• Maximum value: 40-120 (40, 50, 60, 70 ... 120).
Two CU 301 front covers are available, one for “bar”
and another for “psi”, i.e. a “bar” front cover can be
replaced by a “psi” front cover.
Note: The pressure sensor must be replaced by a
sensor measuring the pressure in the actual measur-
ing unit.
When the front cover is replaced, the display 5.3.1
Sensor automatically changes from bar to psi or vice
versa.
Relation to other displays:
The measuring unit appearing in display 5.2.2 Actual
pressure will be identical to the measuring unit in the
front cover.
Exception: If “Manual” is selected in display
5.3.2 Choice of sensor, the sensor can be set, irre-
spective of the front cover.
If changes are made in display 5.3.1 Sensor, the set-
ting in display 5.3.2 Choice of sensor is changed to
“Manual”.
If the original setting is resumed, it is necessary to
change the setting in display 5.3.2 Choice of sensor
from “Manual” to “Automatic”.
5.3.2 Choice of sensor
The following settings are available:
•Automatic.
•Manual.
Relation to other displays:
If, for some reason, the setting in this display has
changed to “Manual” and this is changed to “Auto-
matic”, the setting of the displays 5.3.1 Sensor and
5.3.3 Maximum pressure setting will change to the
factory setting.
5.3.3 Maximum pressure setting
The setting of this display overrules the possibility of
using the arrow button on the CU 301 front to in-
crease the pressure to a setting above the “Maxi-
mum pressure setting”.
The following settings are available:
•2, 2.5 ... 5.0 bar.
Relation to other displays:
The setting of this display overrules the possibility of
using the display 5.1.1 Pressure setting to increase
the pressure to a setting above the “Maximum pres-
sure setting”.
If the setting is changed from 5.0 bar, the setting in
display 5.3.2 Choice of sensor changes from “Auto-
matic” to “Manual”.
TM CU301_2_06 GBTM CU301_3_01 GB
TM CU301_3_02 GBTM CU301_3_03 GB

17
5.3.4 Automatic restart
Set the automatic restart time from stop, caused by
an alarm, to restart attempt.
The following settings are available:
Time:
•0:05.
• “–” (not active).
•1, 2, ... 30 m (1 min. intervals),
30, 45, 1 h, ... 2h (15 min. intervals),
2h 30 m, 3h, ... 4 h (30 min. intervals).
Double:
•Yes.
•No.
When “Yes” is selected, the restart time set will be
doubled automatically for every 10 motor stops
caused by an alarm. The time is doubled up to a stop
time of 4 hours. After 10 hours of operation without
an alarm, the restart time is automatically set to:
• the time set in the “Time” field or
•5 min. (factory setting) if no setting was made in
the “Time” field.
5.3.5 Dry-running stop
The dry-running stop value is factory-set.
The value depends on the actual motor.
The factory setting depends on the power rating of
the motor.
The following settings are possible:
• Motor type 0.1 to 0.63 kW, dry-running stop =
300 W.
• Motor type 0.7 to 1.05 kW, dry-running stop =
680 W.
• Motor type 1.1 to 1.73 kW, dry-running stop =
800 W.
When the dry-running protection is to be active, the
minimum value of the pump power input must be set
in this display.
Setting range: 0-2500 W (10 W intervals).
Relation to other displays:
The actual pump power input can be read in display
5.2.5 Power input and power consumption.
If the maximum pump speed has been reduced in
display 5.3.6 Maximum speed, the dry-running stop
value must be changed.
5.3.6 Maximum speed
Set the maximum speed.
Setting range: 3,000-10,700 min-1 (100 min-1 inter-
vals).
Dry-running stop at reduced maximum pump
speed:
If the maximum pump speed has been reduced, the
dry-running stop value in display 5.3.5 Dry-running
stop must be changed.
Calculating the minimum power limit:
Note: The calculated value is used in display
5.3.5 Dry-running stop.
Note: If the pump is worn, a renewed calculation of
the minimum power limit may be required.
5.3.7 Buttons on CU 301
The buttons on the CU 301 can be set to:
•Active.
•Not active.
TM CU301_3_04 GBTM CU301_3_05 GB
TM CU301_3_06 GB
Step Action
1Start the pump against closed discharge
valve.
2Read the power input (P1) in display
5.2.5 Power input and power consump-
tion.
3Calculate the minimum power limit as fol-
lows:
Power limit [W] = P1· 0.9.
TM CU301_3_07 GB

18
5.3.8 Indication of pump operation
The following settings are available:
•Running light.
•Constant light.
5.3.9 Number
Allocate a number to the CU 301 and the pump con-
nected. The CU 301 and the pump must have the
same number.
Setting range: “–” (not active), 1, 2, ... 64.
Once a number setting has been made, the factory
setting (not active) is no longer available.
If the CU 301 and the pump do not have the same
number, the alarm “No contact to pump” will be indi-
cated.
TM CU301_3_08 GBTM CU301_3_09 GB

19
6. Fault finding
6.1 Service
The CU 301 continuously receives operating data
from the pump. In case of an alarm, the service indi-
cator light is permanently on, see fig. 17.
Fig. 17
The service indicator light will be permanently on if
one of the following alarm situations occurs:
• Sensor defective.
• Overload.
• Overtemperature.
• Speed reduction.
• Voltage alarm.
• No contact to pump.
To identify the cause of the service alarm, it is
necessary to remove the front cover from the
CU 301. Fit the front cover as shown in fig. 18 to
avoid disconnecting the multi-core cable.
A number of LEDs are mounted on the supply board
inside the CU 301, see section 4. Position of LEDs
and fuse.
Fig. 18 shows the LEDs and the alarm texts on the
supply board.
Fig. 18
Before starting any work on the CU 301,
make sure that the electricity supply has
been switched off and that it cannot be ac-
cidentally switched on.
TM01 8327 4701
bar
5.0
4.5
4.0
3.5
3.0
2.5
2.0
TM01 8435 1703
MIN. SPEED
CONTROL INDICATOR
SENSOR DEFECTIVE
OVER LOAD
OVERTEMPERATURE
SPEED REDUCTION
VOLTAGE ALARM
NO CONTACT TO PUMP
MAX. SPEED
CU 301
bar
5.0
4.5
4.0
3.5
3.0
2.5
2.0

20
Fault Possible cause Remedy
1. No light in the
front cover. a) The multi-core connection is mis-
placed or defec-
tive.
• Is the control indicator LED flashing?
If not, the CU 301 is defective.
• Check that the multi-core cable connection is OK.
If so, the CU 301 is defective.
2. The pump does
not start.
The green indi-
catorlight in the
on/off button is
on.
No alarm is in-
dicated.
a) The CU 301 or
the pump is de-
fective.
Check
• that the control indicator LED is flashing.
If not, the CU 301 is defective.
• that the system pressure is 0.5 bar below the pressure set-
ting.
If so, the pump is supposed to start. Open a tap to be sure.
If the pump starts, the system is probably OK.
The system pressure can be read on the pressure gauge.
• See point 13. to check the pressure sensor.
If the pump has not started yet, proceed as follows:
• Press the on/off button for 5 seconds.
If the pump starts, the CU 301 or the sensor may be defective.
Note: The pressure is not controlled and may rise to a high
level.
3. The pressure is
not constant. a) The pump is not of the correct type
or the precharge
pressure of the
diaphragm tank is
incorrect.
Check
• that the LED for Max. speed or Min. speed is on.
If so, this indicates that the pump has reached a limit.
See section 1.3 System sizing.
Replace the pump, if necessary.
• the precharge pressure of the diaphragm tank.
Note: Remember to stop and drain the system before the
pressure is checked.
• whether the sensor is positioned far away from the tap.
If so, the pressure variations may be caused by friction
losses, see section 1.4 Positioning the pressure sensor.
4. The pump is
running con-
tinuously.
a) The pump cannot
deliver the pres-
sure set.
The CU 301 or
the sensor is de-
fective.
• Try to lower the pressure set, see section 1.3 System sizing.
Note that the pump may run for about 15 to 20 seconds be-
fore it stops.
• Check that the control indicator LED is flashing.
• Check that the pipe end of the sensor is not blocked.
If so, remove the blockage.
• Try to stop the pump by means of the on/off button.
If this is not possible, the CU 301 is defective.
Replace the CU 301.
• See point 13. to check the pressure sensor.
(continued on the following pages)