8.4.24 WARNING/ALARM 26, Brake Resistor Power Limit
Cause
The power transmitted to the brake resistor is calculated as a mean value over the last 120 s of run time. The calculation is based on the
DC-link voltage and the brake resistor value set in parameter 2-16 AC Brake Max. Current. The warning is active when the dissipated
braking power is higher than 90% of the brake resistor power. If option [2] Trip is selected in parameter 2-13 Brake Power Monitoring, the
drive trips when the dissipated braking power reaches 100%.
8.4.25 WARNING/ALARM 27, Brake Chopper Fault
Cause
The brake transistor is monitored during operation, and if a short circuit occurs, the brake function is disabled, and a warning is issued.
The drive is still operational, but since the brake transistor has short-circuited, substantial power is transmitted to the brake resistor,
even if it is inactive.
Troubleshooting
• Remove the power to the drive and remove the brake resistor.
8.4.26 WARNING/ALARM 28, Brake Check Failed
Cause
The brake resistor is not connected or not working.
Troubleshooting
• Check parameter 2-15 Brake Check.
8.4.27 ALARM 29, Heat Sink Temp
Cause
The maximum temperature of the heat sink is exceeded. The temperature fault is not reset until the temperature drops below a
defined heat sink temperature. The trip and reset points are different based on the drive power size.
Troubleshooting
• The ambient temperature is too high.
• The motor cables are too long.
• Incorrect airflow clearance above and below the drive.
• Blocked airflow around the drive.
• Damaged heat sink fan.
• Dirty heat sink.
8.4.28 ALARM 30, Motor Phase U Missing
Cause
Motor phase U between the drive and the motor is missing.
Maintenance, Diagnostics, and
Troubleshooting
Operating Guide | VLT® Refrigeration Drive FC 103
AQ275652766279en-000101 / 130R0707| 107
Danfoss A/S © 2020.01
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