Unit installation

CDU Installation Guide Page 44
Cooling Distribution Unit
TROUBLESHOOTING (continued)
Code: a14 – ‘Pump P2 inverter low flow’ (engineer to clear)
Pump P2 has not reached the correct differential pressure in the specified time limit
via the inverter drive. Alarm will cancel when inverter receives a reset signal.
Action: Check unit has been set up for the correct number of racks. Check inverter
drive for faults. Check non-return valves are not sticking open.
Code: a15 – ‘Pump P1 DOL overload’ (self clear)
Pump P1 is drawing more than thermal overload current setting when driven direct on
line. Alarm will cancel when thermal relay is reset.
Action: Reset overload then, force Pump 1 to run using ‘Manual Control’ function and
measure current drawn by pump. If higher than overload setting (see wiring
diagram), then pump should be replaced.
Code: a16 – ‘Pump P1 DOL low flow’ (engineer to clear)
Pump P1 has not reached the correct differential pressure in the specified time limit
when driven direct on line.
Action: Check unit has been set up for the correct number of racks. Check non-return
valves are not sticking open.
Code: a17 – ‘Pump P2 DOL overload’ (self clear)
Pump P2 is drawing more than thermal overload current setting when driven direct on
line. Alarm will cancel when thermal relay is reset.
Action: Reset overload, then force Pump 2 to run using ‘Manual Control’ function and
measure current drawn by pump. If higher than overload setting (see wiring
diagram), then pump should be replaced.
Code: a18 – ‘Pump P2 DOL low flow’ (engineer to clear)
Pump P2 has not reached the correct differential pressure in the specified time limit
when driven direct on line.
Action: Check unit has been set up for the correct number of racks. Check non-return
valves are not sticking open.
Code: a19 – ‘Pump shutdown’ (engineer to clear)
Unit has cycled through all pump control options after inverter & pump fault alarms,
i.e. Pump 1 Inverter fault, Pump 2 Inverter fault, Pump 1 DOL fault, Pump 2 DOL fault.
Unit will revert to Pump 1 Inverter when alarms are cleared.
Action: Check running current of pumps, check inverter for faults.
Code: a20 + a21 – ‘Valve 1 & 2 fault’ (engineer to clear)
Feedback signal from both valves is more than 10% adrift from demand signal -
allowing for positioning time.
Action: As for w20 & w21 warnings.
Code: a28 – ‘Flood unit’ or ‘Flood unit’ selectable - alarm or alarm + shutdown (engineer
to clear)
Level switch in cabinet drip tray has detected a substantial water leak.
Action: Identify and repair leak (Note: a leak of this magnitude that does not bring up
any other alarms, will most likely be from the Primary circuit).
Code: a29 – ‘Sec temp T2b out of range’ (self clear)
Reading from secondary temperature sensor T2b is outside the nominated range of -
31°C to +66°C (-23.8°F to +150.8°F).
Action: Check sensor connections to the control board.
Code: a30 – ‘Sec temp diff error’ (self clear)
Reading difference between secondary temperature sensors T2a and T2b is more
than 1°C (2°F) for a period of 2 minutes or more.
Action: Check both sensors against temperature sensor resistance chart in Section
8.2 and replace the faulty unit.