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WARNING/ALARM 3, No motor
No motor has been connected to the output of the adjustable frequency drive. This warning or
alarm will only appear if programmed by the user in par. 1-80
Function at Stop
.
Troubleshooting:
Check the connection between the adjustable frequency drive and the motor.
WARNING/ALARM 4, Mains phase loss
A phase is missing on the supply side, or the line voltage imbalance is too high. This message also
appears for a fault in the input rectifier on the adjustable frequency drive. Options are programmed
at par. 14-12
Function at Mains Imbalance
.
Troubleshooting:
Check the supply voltage and supply currents to the adjustable frequency
drive. See Section 5.1.2 for troubleshooting details.
WARNING 5, DC link voltage high
The intermediate circuit voltage (DC) is higher than the high voltage warning limit. The limit is
dependent on the adjustable frequency drive voltage rating. The adjustable frequency drive is still
active.
See ratings table in Section 1.9 for the voltage limits.
WARNING 6, DC link voltage low
The intermediate circuit voltage (DC) is lower than the low voltage warning limit. The limit is
dependent on the adjustable frequency drive voltage rating. The adjustable frequency drive is still
active.
See ratings table in Section 1.9 for the voltage limits.
WARNING/ALARM 7, DC overvoltage
If the intermediate circuit voltage exceeds the limit, the adjustable frequency drive trips after a
time.
Troubleshooting:
Connect a brake resistor
Extend the ramp time
Change the ramp type
Activate functions in par. 2-10
Brake Function
Increase par. 14-26
Trip Delay at Inverter Fault
See ratings table in Section 1.9 for the voltage limits. See Section 5.1.1 for troubleshooting details.
WARNING/ALARM 8, DC undervoltage
If the intermediate circuit voltage (DC) drops below the undervoltage limit, the adjustable fre-
quency drive checks if a 24 V backup supply is connected. If no 24 V backup supply is connected,
the adjustable frequency drive trips after a fixed time delay. The time delay varies with unit size.
See ratings table in Section 1.9 for the voltage limits.
Troubleshooting:
Make sure that the supply voltage matches the adjustable frequency drive voltage.
Perform Input voltage test (Section 6.3.2)
Perform soft charge and rectifier circuit test (Section 6.2.1 or 6.2.3)
4 Troubleshooting
High Power Service Manual for VLT
®
FC Series
Adjustable Frequency Drives
4-10
MG.90.L1.22 - VLT
®
is a registered Danfoss trademark
4
Summary of Contents for VLT HVAC FC 100
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