circuited, substantial power is transmitted to
the brake resistor, even if it is inactive.
Turn off the adjustable frequency drive and
remove the brake resistor.
Warning: There is a risk of sub-
stantial power being transmit-
ted to the brake resistor if the
brake transistor is short-circuit-
ed.
ALARM/WARNING 28
Brake check failed:
Brake resistor fault: the brake resistor is not
connected/working.
ALARM 29
Adjustable frequency drive over-tem-
perature:
If the enclosure is IP 20 or IP 21/TYPE 1, the
cut-out temperature of the heatsink is 203
o
F
+9
o
[95
o
C +5
o
C], depending on the size of the
adjustable frequency drive. The temperature
fault cannot be reset until the temperature of
the heatsink is below 158
o
C +5
o
F [70
o
C
+5
o
C].
The fault could be a result of:
- Ambient temperature too high
- Motor cable too long
ALARM 30
Motor phase U missing:
Motor phase U between the adjustable fre-
quency drive and the motor is missing.
Turn off the adjustable frequency drive and
check motor phase U.
ALARM 31
Motor phase V missing:
Motor phase V between the adjustable fre-
quency drive and the motor is missing.
Turn off the adjustable frequency drive and
check motor phase V.
ALARM 32
Motor phase W missing:
Motor phase W between the adjustable fre-
quency drive and the motor is missing.
Turn off the adjustable frequency drive and
check motor phase W.
ALARM 33
Soft-charge fault:
Too many power-ups have occurred within a
short time period. See the chapter
Specifica-
tions
for the allowed number of power-ups
within one minute.
WARNING/ALARM 34
Ser. com. bus fault:
The serial communication bus on the commu-
nication option card is not working.
WARNING 35
Out of frequency range:
This warning is issued if the output frequency
has reached its W
arning speed low
(par. 4-52)
or
Warning speed high
(par. 4-53). If the ad-
justable frequency drive is in P
rocess control
,
closed-loop
(par. 1-00), the warning is active
in the display. If the adjustable frequency
drive is not in this mode, bit 008000 Out of
frequency range
in extended status word is
active but there is no warning in the display.
ALARM 38
Internal fault:
Contact the local Danfoss supplier.
WARNING 47
24 V supply low:
The external 24 V DC back-up power supply
may be overloaded; otherwise, contact your
local Danfoss supplier.
WARNING 48
1.8 V supply low:
Contact the local Danfoss supplier.
ALARM 50
AMA calibration failed:
Contact the local Danfoss supplier.
ALARM 51
AMA check Unom and Inom:
The setting of motor voltage, motor current
and motor power is presumably wrong. Check
the settings.
7. Troubleshooting VLT
®
HVAC Drive Instruction Manual
136
MG.11.A4.22 - VLT
®
is a registered Danfoss trademark
7
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