Mitsubishi FR-A740-00023-EC Instruction Manual page 406

Causes and corrective actions
(2) Warnings
When the protective function is activated, the output is not shut off.
Operation Panel
Indication
Name
Description
Check point
Corrective action
Operation Panel
Indication
Name
Description
Check point
Corrective action
Operation Panel
Indication
Name
Description
Check point
Corrective action
396
OL
Stall prevention (overcurrent)
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
During
operation level, etc.), this function stops the increase in frequency until the overload
acceleration current decreases to prevent the inverter from resulting in overcurrent shut-off. When
the overload current has decreased below stall prevention operation level, this function
increases the frequency again.
When the output current (output torque during real sensorless vector control or vector
During
control) of the inverter exceeds the stall prevention operation level (Pr. 22 Stall prevention
constant- operation level, etc.), this function reduces frequency until the overload current
decreases to prevent the inverter from resulting in overcurrent shut-off. When the
speed
overload current has decreased below stall prevention operation level, this function
operation
increases the frequency up to the set value.
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
During
operation level, etc.), this function stops the decrease in frequency until the overload
current decreases to prevent the inverter from resulting in overcurrent shut-off. When
deceleration
the overload current has decreased below stall prevention operation level, this function
decreases the frequency again.
1. Check that the Pr. 0 Torque boost setting is not too large.
2. Check that the Pr. 7 Acceleration time and Pr. 8 Deceleration time settings are not too small.
3. Check that the load is not too heavy.
4. Are there any failure in peripheral devices?
5. Check that the Pr. 13 Starting frequency is not too large.
· Check the motor for use under overload.
1. Increase or decrease the Pr. 0 Torque boost value 1% by 1% and check the motor status. (Refer to page 138.)
2. Set a larger value in Pr. 7 Acceleration time and Pr. 8 Deceleration time. (Refer to page 167.)
3. Reduce the load weight.
4. Try advanced magnetic flux vector control, real sensorless vector control or vector control.
5. Change the Pr. 14 Load pattern selection setting.
6. 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.)
oL
Stall prevention (overvoltage)
· 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 shut-off. As soon as the regenerative energy has
During
decreased, deceleration resumes.
deceleration
· 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 shut-off. (Refer to page 371.)
· Check for sudden speed reduction.
· Regeneration avoidance function (Pr. 882 to Pr. 886) is being used? (Refer to page 371.)
The deceleration time may change.
Increase the deceleration time using Pr. 8 Deceleration time.
PS
PU stop
Stop with of the PU is set in Pr. 75 Reset selection/disconnected PU detection/PU stop selection. (For Pr.
75, refer to page 295.)
Check for a stop made by pressing
Turn the start signal off and release with
FR-PU04
OL
FR-PU07
FR-PU04
oL
FR-PU07
FR-PU04
PS
FR-PU07
of the operation panel.
.