79
VLT
®
3500 HVAC
MG.35.B1.02 – VLT is a registered Danfoss trademark
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Warning:
Touching the electrical parts may be fatal - even after the equipment has
been disconnected from mains.
Using VLT 3502-3562 HVAC: wait 4 minutes
Using VLT 3542-3562 (230 V) HVAC: wait 14 minutes
Using VLT 3575-3800 HVAC: wait 14 minutes
Fault messages
Inverter fault
The power section of VLT 3500 HVAC is defective.
Overvoltage
The voltage of the intermediate circuit (DC voltage) is
too high. Possible reasons: mains voltage too high,
transients on the mains voltage, or regenerative motor
operation.
Note: When VLT 3500 HVAC stops via ramps, energy
from the motor is returned to the frequency converter
(regenerative operation), which charges the
intermediate circuit.
•
If the fault message is given when the speed is
ramped down, the ramp-down time can be
increased.
If the fault message arises in other situations, the pro-
blem is probably in the mains supply.
Undervoltage
The voltage of the intermediate circuit of the
frequency converter (DC current) is too low. Possible
reasons: Mains voltage too low or a fault on the
charging circuit/rectifier of the frequency converter.
•
Check whether the mains voltage is in order.
Overcurrent
The upper limit of the rectifier peak current is reached,
possibly because of a short-circuiting of the
frequency converter output.
•
Check that there is no short-circuiting at the motor
or in the motor cable.
Ground fault
A ground fault on VLT 3500 HVAC's output. Another
possibility is that the motor cable is too long.
•
Check under technical data to find out how long
the cable must be. Check whether motor and mo-
tor cable have been grounded correctly.
■
Critical temperature
The temperature inside VLT 3500 HVAC is too high.
Possible causes: Ambient temperature too high (max.
40/45°C), the heat sink ribs of the frequency conver-
ter have been covered, or the fan is out of order.
•
Reduce the ambient temperature by increasing the
amount of ventilation. Clear/clean the heat sinks.
Replace the fan if faulty.
Overload
The electronic VLT 3500 HVAC protection is active.
This means that the motor has consumed more than
110% of the rated current of the frequency converter
for too long.
•
Reduce the motor load. If this is not possible, the
application may require a larger frequency conver-
ter.
Motor trip
The electronic motor protection is active. This means
that the current consumed by the motor at low speed
has been too high for too long.
•
The motor has been loaded excessively at low
speed. If the load cannot be changed, the motor
has to be replaced by a bigger version, or extra
cooling must be provided for the existing motor.
Subsequently, the electronic motor protection can
be de-activated in parameter 315.
NB!:
Electrostatic discharges
Important! Many electronic components are
sensitive to static electricity. Even voltages so
low that they cannot be felt, seen or heard,
may impair components or damage them
completely.
Discharge of static electricity can have the
following unpleasant consequence: the service
life of components is reduced.
4.4 Fault messages
