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Causes and corrective actions
(2) Warning
When the protective function is activated, the output is not shut off.
Operation Panel
Indication
OL
FR-PU04
FR-PU07
OL
Name
Stall prevention (overcurrent)
Description
During
acceleration
When the output current (output torque during Real sensorless vector control or vector
control) of the inverter exceeds the stall prevention operation level (Pr. 22 Stall prevention
operation level, etc.), this function stops the increase in frequency until the overload
current decreases to prevent the inverter from resulting in overcurrent trip. When the
overload current has decreased below stall prevention operation level, this function
increases the frequency again.
During
constant
speed
operation
When the output current (output torque during Real sensorless vector control or vector
control) of the inverter exceeds the stall prevention operation level (Pr. 22 Stall prevention
operation level, etc.), this function reduces frequency until the overload current
decreases to prevent the inverter from resulting in overcurrent trip. When the overload
current has decreased below stall prevention operation level, this function increases the
frequency up to the set value.
During
deceleration
When the output current (output torque during Real sensorless vector control or vector
control) of the inverter exceeds the stall prevention operation level (Pr. 22 Stall prevention
operation level, etc.), this function stops the decrease in frequency until the overload
current decreases to prevent the inverter from resulting in overcurrent trip. When the
overload current has decreased below stall prevention operation level, this function
decreases the frequency again.
Check point
· Check that the Pr. 0 Torque boost setting is not too large.
· Check that the Pr. 7 Acceleration time and Pr. 8 Deceleration time settings are not too small.
· Check that the load is not too heavy.
· Are there any failure in peripheral devices?
· Check that the Pr. 13 Starting frequency is not too large.
· Check the motor for use under overload.
· Check that Pr. 22 Stall prevention operation level is appropriate.
Corrective action
· Increase or decrease the Pr. 0 Torque boost value 1% by 1% and check the motor status. (Refer to page
146.)
· Set a larger value in Pr. 7 Acceleration time and Pr. 8 Deceleration time. (Refer to page 172.)
· Reduce the load weight.
· Try Advanced magnetic flux vector control, Real sensorless vector control or vector control.
· Change the Pr. 14 Load pattern selection setting.
· Set stall prevention operation current in Pr. 22 Stall prevention operation level. (The initial value is
150%.) The acceleration/deceleration time may change. Increase the stall prevention operation level
with Pr. 22 Stall prevention operation level, or disable stall prevention with Pr. 156 Stall prevention
operation selection. (Use Pr. 156 to set either operation continued or not at OL operation.)
Operation Panel
Indication
oL
FR-PU04
FR-PU07
oL
Name
Stall prevention (overvoltage)
Description
During
deceleration
· If the regenerative energy of the motor becomes excessive and exceeds the
regenerative energy consumption capability, this function stops the decrease in
frequency to prevent overvoltage trip. As soon as the regenerative energy has
decreased, deceleration resumes.
· If the regenerative energy of the motor becomes excessive when regeneration
avoidance function is selected (Pr. 882 = 1), this function increases the speed to
prevent overvoltage trip. (Refer to page 383.)
Check point
· Check for sudden speed reduction.
· Regeneration avoidance function (Pr. 882 to Pr. 886) is being used? (Refer to page 383.)
Corrective action
The deceleration time may change. Increase the deceleration time using Pr. 8 Deceleration time.
Operation Panel
Indication
PS
FR-PU04
FR-PU07
PS
Name
PU stop
Description
Stop with of the PU is set in Pr. 75 Reset selection/disconnected PU detection/PU stop selection. (For
Pr. 75, refer to page 305.)
Check point
Check for a stop made by pressing of the operation panel.
Corrective action
Turn the start signal OFF and release with .