Grundfos CU 301 Mode D'emploi page 25

Fault Possible cause
11 CU 301 The temperature sensor in the motor is sensing a temperature above the values
indicates stated in the factory settings. See section
"Overtemperat
a)
ure".
12 CU 301 a)
indicates
"Overload".
b)
13 CU 301 a)
indicates
"Sensor
defective".
14 The pump is a)
operating on
and off.
15 Excess a)
pressure for a
short moment
at start of
consumption.
Related information
3.3 Positioning the pressure sensor
4.2 System sizing
5.6 Service alarm
5.8 Position of LEDs
6.3.11 Number
6.3.7 Dry-running stop
6.3.8 Maximum speed
9. Technical data
10. Pressure sensor voltage chart
Insufficient cooling of
the motor.
The pump is worn or
blocked.
The pump is too large
for the installed motor.
The pressure sensor is
defective.
No communication.
Cut-in speed is too high. Reduce the cut-in speed, see section
Remedy
9. Technical data.
Restore correct cooling of the motor. The flow
velocity past the motor must be at least 0.15 m/s.
The pump must be serviced.
Replace the pump or motor.
Check that the sensor is installed correctly.
Check that the Grundfos GO Remote setting of
the sensor is correct.
Check the sensor values according to the
pressure sensor voltage chart. See
sensor voltage chart.
If the sensor type is 4-20 mA, measure the signal
current.
If the current is above 2 mA, the sensor and wiring
are OK.
If the current is below 2 mA, the sensor or wiring
is defective.
Replace defective parts.
Are the LED "Sensor defective" and the LED, pos.
1, on? See section 5.8 Position of
• Yes: The total load of 24 VDC from terminal 5
is above 100 mA.
Disconnect the sensor in order to determine if
it is defective.
Replace defective sensor.
• No: The load is OK, but the CU 301 sensor
input may be defective.
Check that the LED "No contact to pump" is on.
If so, CU 301 starts and stops the pump, based on
the sensor signal only. CU 301 has to be reset
every 1000 stops.
Refer to fault 5 for remedy.
6.3.8 Maximum speed.
10. Pressure
LEDs.
25