Danfoss VLT HVAC Operating Instructions Manual page 124

7. Troubleshooting
WARNING 6
DC link voltage low
The intermediate circuit voltage (DC) is below
the undervoltage limit of the control system.
The frequency converter is still active.
WARNING/ALARM 7
DC over voltage:
If the intermediate circuit voltage exceeds the
limit, the frequency converter trips after a
time.
Possible corrections:
Connect a brake resistor. Extend the ramp
7
time
Alarm/warning limits:
Voltage
ranges
Undervoltage
Voltage
warning low
Voltage
warning high
(w/o brake -
w/brake)
Overvoltage
The voltages stated are the intermediate circuit
voltage of the frequency converter with a tol-
erance of ± 5 %. The corresponding mains
voltage is the intermediate circuit voltage (DC-
link) divided by 1.35
WARNING/ALARM 8
DC under voltage:
If the intermediate circuit voltage (DC) drops
below the "voltage warning low" limit (see ta-
ble above), the frequency converter checks if
24 V backup supply is connected.
If no 24 V backup supply is connected, the
frequency converter trips after a given time
depending on the unit.
To check whether the supply voltage matches
the frequency converter, see
WARNING/ALARM 9
Inverter overloaded:
The frequency converter is about to cut out
because of an overload (too high current for
too long). The counter for electronic, thermal
124
Connect a brake resistor
Extend the ramp time
Activate functions in par. 2-10
Increase par. 14-26
3 x 200 - 3 x 380 - 3 x 525 -
240 V 480 V 600 V
[VDC] [VDC] [VDC]
185 373 532
205 410 585
390/405 810/840 943/965
410 855 975
Specifications
MG.11.A4.02 - 09.10.06. VLT
®
VLT HVAC Drive Operating Instructions
inverter protection gives a warning at 98%
and trips at 100%, while giving an alarm. Re-
set cannot be performed before counter is
below 90%.
The fault is that the frequency converter is
overloaded by more than 100% for too long.
WARNING/ALARM 10
Motor ETR over temperature:
According to the electronic thermal protection
(ETR), the motor is too hot. It can be chosen
if the frequency converter is to give a warning
or an alarm when the counter reaches 100%
in par. 1-90. The fault is that the motor is
overloaded by more than 100% for too long.
Check that the motor par. 1-24 is set correctly.
WARNING/ALARM 11
Motor thermistor over temp:
The thermistor or the thermistor connection is
disconnected. Choose if the frequency con-
verter is to give a warning or an alarm when
the counter reaches 100% in par. 1-90. Check
that the thermistor is connected correctly be-
tween terminal 53 or 54 (analog voltage input)
and terminal 50 (+ 10 Volts supply), or be-
tween terminal 18 or 19 (digital input PNP
only) and terminal 50. If a KTY sensor is used,
check for correct connection between terminal
54 and 55.
WARNING/ALARM 12
Torque limit:
The torque is higher than the value in par.
4-16 (in motor operation) or the torque is
higher than the value in par. 4-17 (in regen-
erative operation).
.
® is a registered Danfoss trademark