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Causes and corrective actions
6
TROUBLESHOOTING
(2) Warning
When a warning occurs, the output is not shut off.
Operation panel
indication
OL
Name
Stall prevention (overcurrent)
Description
During
acceleration
When the output current (output torque when Pr. 277 Stall prevention current switchover = "1") 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 reduced below stall prevention
operation level, this function increases the frequency again.
During
constant-
speed
operation
When the output current (output torque when Pr. 277 Stall prevention current switchover = "1") 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 reduced below stall prevention operation level, this
function increases the frequency up to the set value.
During
deceleration
When the output current (output torque when Pr. 277 Stall prevention current switchover = "1") 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 that the Pr. 22 Stall prevention operation level is appropriate
Corrective action
Increase or decrease the Pr. 0 Torque boost setting 1% by 1% and check the motor status. (Refer to page 94)
Set a larger value in Pr. 7 Acceleration time and Pr. 8 Deceleration time. (Refer to page 116)
Reduce the load weight.
Try Advanced magnetic flux vector control and General-purpose magnetic flux 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. (Operation at OL
occurrence can be selected using Pr. 156.)
Operation panel
indication
oL
Name
Stall prevention (overvoltage)
Description
During
deceleration
If the regenerative energy of the motor becomes excessive to exceed the regenerative energy
consumption capability, this function stops the decrease in frequency to prevent overvoltage trip.
As soon as the regenerative energy has reduced, 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 174).
Check point
Check for sudden speed reduction.
Check that regeneration avoidance function (Pr. 882, Pr. 883, Pr. 885, Pr. 886) is used. (Refer to page 174).
Corrective action The deceleration time may change. Increase the deceleration time using Pr. 8 Deceleration time.
Operation panel
indication
PS
Name
PU stop
Description
Stop with on the operation panel is selected in Pr. 75 Reset selection/PU stop selection.
(For Pr. 75 refer to page 165 .)
Check point
Check for a stop made by pressing of the operation panel.
Corrective action
Turn the start signal OFF and release with .