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Neptune DWC RM100 in-rack Coolant Distribution Unit
Code
A25
Secondary Water High Temperature
Secondary water temperature has risen by more than 2°C (4°F) above set point (default). Alarm will
cancel when temperature falls to 1°C (2°F) above set point or lower. If Dew Point Offset is active, then
Detail:
this alarm will activate at a pre-set default value of 20°C (70°F) – see Configuration/Temperature
Control/P308 (default 2 minute delay applies).
Action:
Check operation of control valve
A26
Water Detected (Internal Leak)
Leak tape in unit drip tray has detected a substantial water leak. Event may be set for 'Alarm Only'
Detail:
(default), or 'Alarm + Unit Shutdown'.
Identify and repair the leak (Note: A leak of this magnitude that does not bring up any other alarms,
Action:
would most likely be from the Primary circuit.
A27
Sec. Over Pressure (Alarm)
Pressure at PS3 has increased above the set value of 6Bar (87PSI) (default). This alarm is only active if
Detail:
unit has been configured for alarm only (See Configuration/Pump Control/P211).
Most likely cause will be excessive heat build-up in the system, or a breach between Primary and
Secondary circuits within the plate heat exchanger. Check for High Temp alarms, check bladder in
Action:
expansion vessel(s) has not ruptured, relieve pressure at drain point. Remove heat exchanger and
replace.
A28*
Water Detected (External Primary Leak)
The water detection tape installed under the floor to the Primary circuit (if fitted – optional extra) has
Detail:
detected a substantial water leak. Alarm may be set for 'Alarm Only' (default), or 'Alarm + Unit
Shutdown'.
Identify and repair leak (note: a leak of this magnitude that does not bring up other alarms will most
Action:
likely be from the Primary chilled water circuit.
A29*
Water Detected (External Secondary Leak)
The water detection tape installed under the floor to the Secondary circuit (if fitted – optional extra)
Detail:
has detected a substantial water leak. Alarm may be set for 'Alarm Only' (default), or 'Alarm + Unit
Shutdown'.
Identify and repair leak (note: a leak of this magnitude that does not bring up other alarms will most
Action:
likely be from the Primary chilled water circuit.
A30
Check Water Make-up Level
Fill pump has run for more than 5 secs (fill pump will run when pressure at PS1 drops fill below the
Detail:
activation threshold - default 0.8 bar (12PSI) for more than 10 seconds, while unit is running in
automatic/on-line mode)
Check amount of fluid in make-up container and re-fill if necessary with treated water (check system
Action:
for any sign of leakage).
A31
System Low Pressure
Pressure at PS1 has dropped more than 0.2Bar (3PSI) (set, non-adjustable) below fill pump activation
Detail:
threshold for more than 1 minute (set, non-adjustable, applicable when unit is running in
automatic/on-line mode).
Check amount of fluid in make-up container and re-fill if necessary. Ensure fill pump hoses are free of
Action:
air locks, container is properly connected and fill pump is operational. Check system for leaks.
A32
Sec. Over Pressure (Alarm + Shutdown)
Pressure at PS3 has increased above the set value of 6Bar (87PSI) (default). This alarm is only active if
Detail:
unit has been configured for alarm + shutdown only (See Configuration - Pump Control).
Most likely cause will be excessive heat build-up in the system, or a breach between Primary and
Secondary circuits within the plate heat exchanger. Check for High Temp alarms, check bladder in
Action:
expansion vessel(s) has not ruptured, relieve pressure at drain point. Remove heat exchanger and
replace.
CDU Operating & Maintenance Guide
Description
Page
Sev.
Self-clear
Latching
✓
2
1
-
✓
2
1
-
1
-
2
-
2
-
✓
1
33
Shutdown
Delay
✓
-
-
✓
✓ (or -)
-
-
-
-
✓
✓(or -)
-
✓
✓(or -)
-
✓
-
-
✓
✓
-
✓
-
-
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