Danfoss VLT MICRO Manual page 77

Possible Faults
o.c. The over-current hardware
trip circuit detects an abnormal
increase in current.
o.u. The AC drive detects that the
internal DC bus voltage has
exceeded its maximum allowable
value.
o.H. The AC drive temperature
sensor detects excessive heat.
L.u. The AC drive detects that the
internal DC bus voltage has fallen
below its min. value.
o.L. The AC motor drive detects
excessive drive output current.
The AC motor drive can withstand
up to 150% of the rated current for
a maximum of 60 seconds.
Corrective Actions
Check the motor output power to insure it
corresponds to the AC drive output power.
Check wiring connections between the AC
drive and motor for possible short circuits.
Increase Acceleration time 1 and 2 (Pr.10, 12).
Check for possible excessive loading conditions
on the motor.
Check the AC line voltage to insure it falls within
the rated AC drive input voltage. Check for
possible voltage transients.
Bus over-voltage could also be caused by
motor regeneration. Either increase the
Deceleration time or add an optional braking
resistor. If a braking resistor is added, check to
insure the required braking power is within the
specified limits of the resistor.
Ensure that the ambient temperature falls within
the specified temperature range.
Check ventilation holes to insure they are not
obstructed.
Remove any foreign objects on the heatsinks
and check for possible dirty heatsink fins.
Provide enough spacing for adequate
ventilation.
Check the AC line voltage to insure it falls within
the rated AC drive input voltage.
Check for motor overloaded.
Reduce the Torque compensation setting
(Pr.54).
Increase the AC drive output capacity
(Pr.25 - 27).
77
® ® ® ® ®
VLT MICRO