Grundfos CU 301 Mode D'emploi page 23

Fault Possible cause
5 CU 301 a)
indicates "No
contact to
pump".
b)
c)
d)
e)
f)
The motor is not an
MSE 3.
The pump cable is
longer than 956 feet.
Cable breakage.
Cross communication
with adjacent CU 301.
The CU 301
communication part is
defective.
The MSE 3 motor
communication part is
defective.
Remedy
If the pump has already worked satisfactorily with
a CU 301 or a CU 300, the motor can be expected
to be an MSE 3.
There is no technical way of determining the
motor type. The only way is to read the nameplate
engraved in the motor sleeve.
Reduce the length of the pump cable.
Switch off the power supply to CU 301.
Connect the motor conductors directly to the
power supply.
Switch on the power supply again. The pump is
now connected directly to the power supply
without interference from CU 301.
Does the motor start?
• Yes: The cable is OK. Go to point d).
• No: Switch off the power supply again.
Remove the cable and cable plug from the
motor and ohm out the cable including the
plug.
Is the cable OK?
• Yes: The motor is defective. Replace the
motor.
• No: Replace the cable.
Note that a megohmmeter ('megger') or other high
voltage device must never be used during
troubleshooting of an SQ pump. This will damage
the internal electronics.
If another CU 301 is installed:
• Ensure each unit has a unique number
assigned. See section Number.
• If pump cables run in parallel to each other,
physically separate them by 12-14 inches or
rewire using a shielded cable.
Are the three CU 301 supply board LEDs in pos.
2, 3 and 4 on and is the control indicator LED
flashing? See section 5.8 Position of
• Yes:
The power supply is OK.
Assign the system a new number.
If this does not work, CU 301 or the motor
communication part is defective.
Replace CU 301 and give the new system a
number between 1 and 64 in order to obtain
correspondence between the numbering of the
SQE pump and CU 301.
Note that two systems on the same power supply
must not have the same number!
Is the LED "No contact to pump" of the new CU
301 also on?
• Yes: CU 301 is OK.
• No: CU 301 which was removed is defective.
As a consequence of the above-mentioned
checks, replace the MSE 3 motor.
LEDs.
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