Warning And Alarm Messages From The Cu; Pressing The Off/Reset Button - Grundfos CU 321 Installation And Operating Instructions

5.2 Warning and alarm messages from the
CU 321
The CU 321 display gives information about warn-
ings/alarms by writing "Err" and a specific code.
Warning and alarm messages:
• Sensor defective
• Overload
• Overtemperature
• Voltage alarm
• Phase error (3-phase only)
• Ground fault
• Short-circuit
• Dry run
• Internal fault.
The last three warning/alarm messages can be
accessed by pressing the button.
Install
The table in section 5.4 Warning and alarm codes
lists the CU 321 warnings and alarms and indicates
how severe a certain alarm is. The most severe fault
cause is an alarm lock.
In case of an alarm lock, the input power must be cut
out, the cause of the fault corrected, and the input
power restored to reset the CU 321.

5.3 Pressing the Off/Reset button

An alarm can be overruled by pressing the Off/ but-
Reset
ton, but if the cause of the alarm has not been
removed, the alarm will reappear. Remember to
press the button to enable the pump after a
On
manual reset.
In addition, an automatic reset may be selected in
the installation menu, which will reset all non-locking
alarms.
Wherever an "X" is placed under both warning and
alarm in the table, see section 5.4 Warning and
alarm codes, this means that a warning precedes the
alarm.
After an alarm lock, the motor will be coasting and
the CU 321 alarm and warning indications will flash.
If the fault is corrected, only the alarm will flash.
The alarm indication stops flashing when the CU 321
is reset.
After a reset, the CU 321 will be ready to start up.
In the following detailed descriptions of warning and
alarm messages, corrective actions to resolve the
condition are recommended.
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