Normal Operation; Troubleshooting And Alarm Messages - Grundfos CU 321 Installation And Operating Instructions

3rd alarm
The 3rd alarm menu displays the alarm code of
the 3rd alarm.
The display shows: AL3 XX (XX = alarm code).
For more information about alarm codes, see
section 5.4.
Older alarms are lost!
Press button to return from the installation
Install
menu.

4.2 Normal operation

Press to enable the pump.
On
The pressure setpoint can be changed during normal
operation.
Press to increase the pressure setpoint.
Press to decrease the setpoint.
Press Off/ to stop the pump.
Reset
Remember to change the pressure in the tank when
the setpoint is changed.
The pressure setpoint (in psi) will appear in the
display during normal operation. The display shows
"PSI" followed by a number between 40 and 100.
The pump will automatically stop when the flow is
low. The Off/ button should only be used when a
Reset
permanent stop is required or when an alarm is
reset.
The display shows: OFF followed by a number.
The number indicates the pressure setpoint in psi.
4.2.1 Operating relay
The CU 321 incorporates an operating relay, termi-
nals 1, 2 and 3, for a potential-free operating signal.
The output, terminals 1, 2 and 3, is electrically sepa-
rated from the rest of the control unit.
The terminals of the relay are connected as follows
according to the pump status:
Pump status Connected terminals
Running 1 and 2
Off due to low flow 1 and 3
Off 1 and 3
Alarm 1 and 3
4.2.2 Display
The display indicates the status of the installation as
follows:
Status Display indication
"PSI", followed by the
Running setpoint in psi,
permanently on
Automatic stop due "PSI", followed by the
to low flow setpoint in psi, flashing
"OFF", followed by the
Off (stop)
setpoint in psi, flashing
18
5. Troubleshooting and alarm
messages
This section includes information regarding trouble-
shooting and alarm messages.
The troubleshooting section includes application-
related issues. It should help you to find and identify
faults and errors in the application.
The warning/alarm messages section is useful in
understanding the CU 321. In case of a failure, see
section 5.2 Warning and alarm messages from the
CU 321.