Danfoss VLT FC 103 Operating page 127

VLT® Refrigeration Drive FC 103
Operating Guide
Troubleshooting
• Check for proper fan operation.
• Cycle power to the drive and check that the fan operates briefly at start-up.
• Check the sensors on the heat sink.
9.3.23 WARNING 25, Brake Resistor Short Circuit
Cause
The brake resistor is monitored during operation. If a short circuit occurs, the brake function is disabled and the warning appears.
The drive is still operational, but without the brake function.
Troubleshooting
• Remove the power to the drive and replace the brake resistor (refer to parameter 2-15 Brake Check).
9.3.24 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 dissipa-
ted braking power is higher than 90% of the brake resistor power. If option [2] Trip is selected in parameter 2-13 Brake Power Monitor-
ing, the drive trips when the dissipated braking power reaches 100%.
9.3.25 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.
9.3.26 WARNING/ALARM 28, Brake Check Failed
Cause
The brake resistor is not connected or not working.
Troubleshooting
•
Check parameter 2-15 Brake Check.
9.3.27 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
Check for the following conditions:
• 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.
9.3.28 ALARM 30, Motor Phase U Missing
Cause
Motor phase U between the drive and the motor is missing.
Danfoss A/S © 2020.09
Maintenance, Diagnostics, and
Troubleshooting
AQ357954340588en-000201 / 130R0881 | 127