Fault Finding; Service - Grundfos CU 301 Installer Manual

6. Fault finding

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.

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.
bar
5.0
4.5
4.0
3.5
3.0
2.5
2.0
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
CONTROL INDICATOR
MIN. SPEED
MAX. SPEED
SENSOR DEFECTIVE
OVER LOAD
OVERTEMPERATURE
SPEED REDUCTION
VOLTAGE ALARM
NO CONTACT TO PUMP
19