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9.4.20 WARNING/ALARM 21, Parameter Error
Cause
The parameter is out of range. The parameter number is shown in the display.
Troubleshooting
Set the affected parameter to a valid value.
9.4.21 WARNING 23, Internal Fan Fault
Cause
The fan warning function is a protective function that checks if the fan is running/mounted. The fan warning can be disabled in
parameter 14-53 Fan Monitor ([0] Disabled).
For drives with DC fans, a feedback sensor is mounted in the fan. If the fan is commanded to run and there is no feedback from the
sensor, this alarm appears. For drives with AC fans, the voltage to the fan is monitored.
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 control card.
9.4.22 WARNING 24, External Fan Fault
Cause
The fan warning function is a protective function that checks if the fan is running/mounted. The fan warning can be disabled in
parameter 14-53 Fan Monitor ([0] Disabled).
For drives with DC fans, a feedback sensor is mounted in the fan. If the fan is commanded to run and there is no feedback from the
sensor, this warning appears. For drives with AC fans, the voltage to the fan is monitored.
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.
9.4.23 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).
9.4.24 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 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%.
9.4.25 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.
AQ262141314214en-000301 / 130R0880140 | Danfoss A/S © 2021.11
Maintenance, Diagnostics, and
Troubleshooting
VLT® HVAC Drive FC 102
Operating Guide
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