Causes and corrective actions
656
PROTECTIVE FUNCTIONS
Operation panel
indication
E.SOT
FR-PU07 Motor step out
Name
Loss of synchronism detection
Description
The inverter trips when the motor operation is not synchronized. (This function is only available under PM
sensorless vector control.)
Check point
• Check that the PM motor is not driven overloaded.
• Check if a start command is given to the inverter while the PM motor is coasting.
• Check if a motor is connected under PM sensorless vector control.
• Check if a PM motor other than the MM-CF series is driven.
Corrective action
• Set the acceleration time longer.
• Reduce the load.
• If the inverter restarts during coasting, set Pr.57 Restart coasting time "9999", and select the automatic
restart after instantaneous power failure.
• Check the connection of the IPM motor.
• For a test run without connecting a motor, select the PM sensorless vector control test operation.(Refer to
page 166.)
• Drive an IPM motor (MM-CF series)
• When driving an IPM motor other than MM-CF series, offline auto tuning must be performed. (Refer to page
452.)
Operation panel
indication
E.BE FR-PU07 Br.Cct.Fault
Name
Brake transistor alarm detection
Description
• The inverter trips if a fault due to damage of the brake transistor and such occurs in the brake circuit. In such
a case, the power supply to the inverter must be shut off immediately.
• Appears when an internal circuit fault occurred for separated converter types and IP55 compatible models.
Check point
• Reduce the load inertia.
• Check that the brake duty is proper.
Corrective action
Replace the inverter.
Operation panel
indication
E.GF FR-PU07 Ground Fault
Name
Output side earth (ground) fault overcurrent
Description
The inverter trips if an earth (ground) fault overcurrent flows due to an earth (ground) fault that occurred on
the inverter's output side (load side).
Check point
Check for an earth (ground) fault in the motor and connection cable.
Corrective action
Remedy the earth (ground) fault portion.
Operation panel
indication
E.LF FR-PU07 E.LF
Name
Output phase loss
Description
The inverter trips if one of the three phases (U, V, W) on the inverter's output side (load side) is lost.
Check point
• Check the wiring. (Check that the motor is normally operating.)
• Check that the capacity of the motor used is not smaller than that of the inverter.
• Check if a start command is given to the inverter while the motor is coasting. (PM sensorless vector control)
Corrective action
• Wire the cables properly.
• Input a start command after the motor stops. Alternatively, use the automatic restart after instantaneous
power failure/flying start function (page 534). (PM sensorless vector control)
Operation panel
indication
E.OHT FR-PU07 OH Fault
Name
External thermal relay operation
Description
The inverter trips if the external thermal relay provided for motor overheat protection or the internally mounted
thermal relay in the motor, etc. switches ON (contacts open).
This function is available when "7" (OH signal) is set in any of Pr.178 to Pr.189 (input terminal function
selection). This protective function is not available in the initial status. (OH signal is not assigned.)
Check point
• Check for motor overheating.
• Check that the value "7" (OH signal) is set correctly to any of Pr.178 to Pr.189 (input terminal function
selection).
Corrective action
• Reduce the load and operation duty.
• Even if the relay contacts are reset automatically, the inverter will not restart unless it is reset.
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