Daikin MicroTech III Operation Manuals page 142

PHA = Phase failure
UzLow = DC-Link Undervoltage
UzHigh = DC-Link Overvoltage
UeHigh = Mains Overvoltage
UeLow = Mains Undervoltage
Question: Can the main voltage be measured at any spot; a data logger may be helpful .
No: Measure the voltage at the power supply input of the concerned fan .
Corrective: • Reset the failure; re-start the motor and observe it .
• If applicable, filter out the source of disturbing signal.
Repeated occurrence:
Question: • Do other fans show the same failure?
• How often does the failure occur?
• Get big electrical consumer loads switched at the same time when the failure occurs in the
surrounding area?
• Are compressors or large asynchronous motors applied within the arrangement?
Yes: Systematic search for external disturbance voltage peaks; If applicable, usage of data logger for
a longer period and analysis of the measured values .
• Are the voltage values within the specified range?
No: It seems to be a hardware problem of the fan . Fan need to be replaced .
OM 920-6 • MICROTECH UNIT CONTROLLER 142
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