Mitsubishi Electric FR-A820-00046 (0.4K) Instruction Manual page 747

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
748
6. PROTECTIVE FUNCTIONS
6.5 Causes and corrective actions
OL
Stall prevention (overcurrent)
• When the output current of the inverter increases, the stall prevention (overcurrent) function is activated.
• The following section explains about the stall prevention (overcurrent) function.
When the output current (output torque under Real sensorless vector control or Vector
control) of the inverter exceeds the stall prevention level (Pr.22 Stall prevention
operation level, etc.), this function stops the increase in frequency until the overload
During acceleration
current decreases to prevent the inverter from resulting in overcurrent trip. When the
overload current is reduced below stall prevention operation level, this function increases
the frequency again.
When the output current (output torque under Real sensorless vector control or Vector
control) of the inverter exceeds the stall prevention level (Pr.22 Stall prevention
During constant- operation level, etc.), this function reduces frequency until the overload current
speed operation decreases to prevent the inverter from resulting in overcurrent trip. When the overload
current is reduced below stall prevention operation level, this function increases the
frequency up to the set value.
When the output current (output torque under Real sensorless vector control or Vector
control) of the inverter exceeds the stall prevention level (Pr.22 Stall prevention
operation level, etc.), this function stops the decrease in frequency until the overload
During deceleration
current decreases to prevent the inverter from resulting in overcurrent trip. When the
overload current is reduced below stall prevention operation level, this function decreases
the frequency again.
• Check that the Pr.0 Torque boost setting is not too large.
• The Pr.7 Acceleration time and Pr.8 Deceleration time settings may be too short.
• Check that the load is not too heavy.
• Check for any failures in peripheral devices.
• Check that the Pr.13 Starting frequency is not too large.
• Check that Pr.22 Stall prevention operation level is appropriate.
• Gradually increase or decrease the Pr.0 setting by 1% at a time and check the motor status. (Refer to
672.)
• Set a larger value in Pr.7 and Pr.8. (Refer to
• Reduce the load.
• Try Advanced magnetic flux vector control, Real sensorless vector control, or Vector control.
• Change the Pr.14 Load pattern selection setting.
• The stall prevention operation current can be set in Pr.22 Stall prevention operation level. (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)
• When the output voltage of the inverter increases, the stall prevention (overvoltage) function is activated.
• The regeneration avoidance function is activated due to excessive regenerative power of the motor. (Refer to
page 696.)
• The following section explains the stall prevention (overvoltage) function.
If the regenerative power of the motor becomes excessive to exceed the regenerative
During deceleration power consumption capability, this function stops decreasing the frequency to prevent
overvoltage trip. As soon as the regenerative power has reduced, deceleration resumes.
• Check for sudden speed reduction.
• Check if the regeneration avoidance function (Pr.882 to Pr.886) is being used. (Refer to
The deceleration time may change. Increase the deceleration time using Pr.8 Deceleration time.
RB
Regenerative brake pre-alarm (Standard models only)
Appears if the regenerative brake duty reaches or exceeds 85% of the Pr.70 Special regenerative brake duty
value. If the regenerative brake duty reaches 100%, a regenerative overvoltage (E. OV[ ]) occurs.
• Check if the brake resistor duty is not too high.
• Check that the Pr.30 Regenerative function selection and Pr.70 settings are correct.
• Set the deceleration time longer.
• Check the Pr.30 and Pr.70 settings. (Refer to
FR-LU08 indication OL
page 349.)
FR-LU08 indication oL
FR-LU08 indication RB
page 689.)
page
page 696.)