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List of fault displays
Fault
Drive unit overload trip
(electronic thermal O/L
relay function) *1
The electronic thermal relay function for drive
unit element protection has been activated.
ySet the acceleration time longer.
yAdjust the Pr.785 PM control torque boost and Pr.795 DC brake
torque boost settings.
yReduce the load.
ySet the surrounding air temperature to within the
specifications.
Motor overload trip
(electronic thermal O/L
relay function) *1
The electronic thermal relay function for motor
protection has been activated.
yReduce the load.
yAdjust the Pr.785 PM control torque boost and Pr.795 DC brake
torque boost settings.
ySet the stall prevention operation level accordingly.
Heatsink overheat The heatsink has overheated.
ySet the surrounding air temperature to within the
specifications.
yClean the heatsink.
yReplace the cooling fan.
Input phase loss *2
One of the three phases on the drive unit input
side has been lost. It may also appear if phase-
to-phase voltage of the three-phase power input
has become largely unbalanced.
yWire the cables properly.
yRepair a break portion in the cable.
yCheck the Pr. 872 Input phase loss protection selection setting.
ySet Pr. 872 Input phase loss protection selection = "0" (without
input phase loss protection) when three-phase input voltage
is largely unbalanced.
Stall prevention stop
yThe rotation speed has dropped to 15r/min as
a result of deceleration due to the excess
motor load.
yOperation was performed without connecting a
motor.
yReduce the load. (Check the Pr. 22 Stall prevention operation
level setting.)
yCheck the connection of the PM motor, or set the PM motor
test operation.
Loss of synchronism
detection
Operation has gone out of synchronism.
ySet the acceleration time longer.
yReduce the load.
yIf the motor is coasting, stop the motor, then input a start
command. Alternatively, use the automatic restart after
instantaneous power failure/flying start function.
yDrive the dedicated PM motor (S-PM series).
Brake transistor alarm
detection
A fault has occurred in the brake circuit, such as
a brake transistor breakage. (In this case, the
drive unit must be powered off immediately.)
Replace the drive unit.
Output side earth
(ground) fault
overcurrent at start *2
An earth (ground) fault has occurred on the drive
unit's output side (detected only at a start).
Remedy the ground fault portion.
Output phase loss
One of the three phases (U, V, W) on the drive
unit's output side (load side) has been lost during
drive unit operation.
yWire the cables properly.
yIf the motor is coasting, stop the motor, then input a start
command.
External thermal relay
operation *2
The external thermal relay connected to the OH
signal has been activated.
yReduce the load and operate less frequently.
yEven if the relay contacts are reset automatically, the drive
unit will not restart unless it is reset.
PTC thermistor operation
*2
Resistance of the PTC thermistor connected
between the terminal 2 and terminal 10 has
reached the Pr.561 PTC thermistor protection level
setting or higher.
Reduce the load.
Parameter storage
device fault
Operation of the component where parameters
are stored (control circuit board) has become
abnormal.
Please contact your sales representative.
When performing parameter writing frequently for
communication purposes, set "1" in Pr. 342 Communication
EEPROM write selection to enable RAM write. Note that
powering OFF returns the drive unit to the status before RAM
write.
Function Name Description Countermeasure Display