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Code
A16
Leak Shutdown / Insufficient Water
On Initial Start-up – if level sensor is not made, fill pressure has not been achieved & fill pump has
been running for more than 1 minute, then unit will not start or shutdown immediately.
Detail:
While Unit is Running – This will be in conjunction with a 'A34 – Level Sensor – No Water Detected'
alarm (refer to A34 for detail). If level sensor is not made and flow of DP is < 50% of flow/DP setpoint,
then unit will shut down after a 1 sec. delay
Check that water make-up container is properly connected (or filling wand is fully immersed, if used).
Action:
Check system for leaks. Check there is no trapped air in fill pump hoses and system is fully vented.
Check auto air vents are open.
A17
Pump 1 Fault
Pump 1 is drawing excessive current, or speed controller has been subjected to over/under voltage.
Detail:
Alarm will only appear after speed controller has gone into fault condition; Pump 2 will then run.
Action:
Replace Pump 1
A18
Pump 2 Fault
Pump 2 is drawing excessive current, or speed controller has been subjected to over/under voltage.
Detail:
Alarm will only appear after speed controller has gone into fault condition; Pump 1 will then run.
Action:
Replace Pump 2
A19
Secondary Pump Flow Shutdown
Detail:
An A17 & A18 – Pump Fault and/or an A43 & A44 – Pump Comms Fault have been generated.
Check running current of pumps, check speed controllers for faults. Faults will need to be rectified &
Action:
alarms cleared before unit can be started again
A20
Valve Fault
Feedback signal from control valve is more than 10% (default) adrift from demand signal (sampled
Detail:
every 15 mins (default) and allowing for 40 second (default) positioning time).
Check the wiring connections to the actuator. Try to set the actuator position using the 'Auto
Action:
Overrides' function. Check the cooling valve demand % and feedback signals (Diagnostics AO04 &
UI13)
A21
Primary Water Low Flow
Will only activate when valve demand is at 100%, 'A25 - Secondary Water High Temp' alarm is active
Detail:
and Primary water temperature is within specified limits (default 5 min. delay applies).
Check operation of control valve. Check primary water supply flow rate. Ensure system heat load does
Action:
not exceed the RM100 capacity (i.e. check that Primary flow is sufficient for heat load – refer to
RM100 Application & Planning Guide
A22
Primary Water Low Temperature
Primary water temperature has dropped below the default 4°C (40°F) threshold. Alarm will cancel
Detail:
when temperature rises to 5°C (42°F) or more (default 2 min. delay applies).
Action:
Check chilled water supply
A23
Primary Water High Temperature
Primary water temperature has risen above the default 11°C (52°F) threshold. Alarm will cancel when
Detail:
temperature falls to 10°C (50°F) or less (default 2 min. delay applies).
Action:
Check chilled water supply
A24
Secondary Water Low Temperature
Secondary water temperature has dropped by more than 2°C (4°F) below set point (default). Alarm
will cancel when temperature rises to 1°C (2°F) below set point or higher. If Dew Point Offset is active,
Detail:
then this alarm will only activate when at or below dew point for a period of 3 minutes or more
(default 2 minute delay applies).
Action:
Check operation of control valve
CDU Operating & Maintenance Guide
Neptune DWC RM100 in-rack Coolant Distribution Unit
Description
Page
Sev.
Self-clear
Latching
1
-
2
-
2
-
1
-
2
-
2
-
✓
3
✓
2
✓
2
32
Shutdown
Delay
✓
✓
-
✓
-
-
✓
-
-
✓
✓
-
✓
-
-
✓
✓
-
✓
-
-
✓
-
-
✓
-
-
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